HETEROSIS IN DAIRY CATTLE AS MEASURED BY BIRTH HEIGHTS, GESTATION LENGTHS, CERTAIN BODY HEIGHTS AND MEASUREMENTS, AND MAMMARY GLAND GRADES
DISSERTATION
Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University
by
GRAYDON WILLIAM BRANDT, B. S., M. S.
The Ohio State University 1958
Approved by:
Adviser Department of Dairy Science ACKNOWLEDGMENTS
Appreciation is expressed to Dr. L. 0. Gilmore, Dr. Fordyce
Ely, and Dr. Tom Ludwick, The Ohio State University, for their interest, encouragement, and advice in conducting this study and in the preparation of the dissertation; to Dr. R. E. Comstock, now of the
Department of Animal Husbandry, University of Minnesota, for outlining the method of analysis and advice during the analyzing of the data; to Professor J. P. LaMaster, former Head, Dairy Department, Clemson
Agricultural College, for permission to use the data; to Professor
C. C. Brannon, who co-operated in obtaining much of the data; to
Professor B. E. Goodale, Head of the Dairy Department, Clemson
Agricultural College, for providing relief from routine duties during the last months of this study; to Dr. Ned D. Bayley and
Dr. R. E. McDowell, Animal Husbandry Research Division, U. S. D. A. for their interest and co-operation during this study.
Appreciation is also expressed to my wife, Frances, for her patience and encouragement over the years, assistance in making the calculations, and in typing the dissertation.
ii TABLE'OF? .
INTRODUCTION ...... V .a ’ v . . • . . . . . ^ ‘ ' 1 ; - ’ 01 , ' * • „ REVIEW OF LITERATURE » • • V • »•»»••
EXPERIMENTAL...... L . * ......
Data « . % 0 . • ......
Source of Data . * ......
Environmental Conditions; Which Have Prevailed •a- Objective and Method Uhetl -in Analyzing Data
Analyses of Data and Res-ultn » % ......
O Birth Weights ......
Gestation Lengths .. » 0„ 3 ...... * . . . •
Measurements of Growth of Calves ......
Mammary Gland Grades » « . » • . • • * • • •
o Weight at First Fresjgen&ugr . 9 ......
SUMMARY" AND CONCLUSIONS ......
APPENDIX ...... 'V* . . . . .
LITERATURE CITED ...... ■*. .» « ; ......
AUTOBIOGRAPHY ...... ’ .' ...... * * ...... LIST OF TABLES
Table
1. Regression of Birth Weight of Calf on Weight of Dam
• 2, Averages of Adjusted Male and Female Weights and Difference by Breed
3* Heritability Estimates for Birth Weight by Sex and Breed ......
• lu Data Used and Calculated H Values for Birth Weights of G x H Females ......
- S• Analyses of Variance of H Values Calculated from Birth Weight Data
6 * Data Used and Calculated H Values for Birth Weights of H x G F e m a l e s ......
7. Data Used and Calculated H Values for Birth Weights of S x H Females ......
8 . Data Used and Calculated H Values for Birth Weights of S x G Females ......
9. Data Used and Calculated II Values for Birth Weights of G x H M a l e s ...... * ......
10. Data Used and Calculated H Values for Birth Weights of H x G Males ......
11. Data Used and Calculated H Values for Birth Weights of S x H Males ......
12. Data Used and Calculated H Values for Birth Weights of S x G Males ......
13* Average Gestation Length by Sequence, Sex and Breed
lU.. Days Added to Gestation Length to Adjust for Sequence by Sex and Breed ......
1$. Averages of Adjusted Gestation Lengths ......
16. Average Gestation Lengths of Calves Born in Cool and Warm Seasons ...... LIST OF TABLES (continued)
Table Page
17* Heritability Estimates for Gestation Length by Sex and Breed ...... 171
18* Data Used and Calculated H Values for Gestation Lengths of G x H Females . . . • ...... 172
19. Analyses of Variance of H Values Calculated from Gestation Length D a t a ...... 175
20. Data Used and Calculated H Values for Gestation Lengths of H x G Females ...... 1?6
21. Data Used and Calculated H Values for Gestation Lengths of S x K Females ...... 179
22. Data Used and Calculated H Values for Gestation Lengths of S x G Females ..... 180
2.3. Data Used and Calculated H Values for Gestation Lengths of H x J F e m a l e s ...... 182
2h* Data Used and Calculated II Values for Gestation Lengths of G x H H a l e s ...... 183
2$„ Data Used and Calculated H Values for Gestation Lengths of H x G Males ...... 185
26. Data Used and Calculated H Values for Gestation Lengths of S x H Males ...... 188
27. Data Used and Calculated H Values for Gestation Lengths of S x G M a l e s ...... 189
28. Heritability Estimates for Weight of Females at 90, 1$0 and 180 Days of A g e ...... 1.97
29* Heritability Estimates for Heart Girth Measurements of Females at 90, l£0 , and 180 Days of Age .... 198
30. Data Used and Calculated H Values for 90 Day Weights of G x H Females ...... 199
31. Analyses of Variance of H Values Calculated from Weight Data ...... 201
32. Data Used and Calculated H Values for 90 Day Weights of H x G Females...... 202
v LIST OF TADLES (continued)
Table Page
33. Data Used and Calculated H Values for l£0 Day Weights of G x H Females 201;
3lw Data Used and Calculated H Values for 1^0 Day Weights of S x H Females ...... 20£
3£. Data Used and Calculated H Values for 180 Day Weights of G x H Females ...... 206
36. Data Used and Calculated H Values for 180 Day Weights of I-I x G Females ...... 207
37* Data Used and Calculated H Values for 180 Day Weights of S x H F e m a l e s ...... 209
38. Data Used and Calculated H Values for 180 Day Weights of S x G Females 210
39• Data Used and Calculated H Values for 90 Day Heart Girths of G x HFe m ales...... 212
1;0. Analyses of Variance Calculated from Heart Girth Data 2li;
Ip.. Data Used and Circulated II Values for 90 Day Heart Girths of II x G Females ...... 215>
U2, Data Used and Calculated H Values for l£0 Day Heart Girths of G x K Females...... 218
1;3. Data Used and Calculated H Values for l£0 Day Heart Girths of H x G Females 219
UU• Data Used and Calculated H Values for 13*0 Day Heart Girths of S x II Females „...... 221
Ii5« Data Used and Calculated H Values for 180 Day Heart Girths of G x H Females • •..•••••.•* 222
I;6 . Data Used and Calculated H Values for 180 Day Heart Girths of H x GFemales ...... 22U hi * Data Used and Calculated H Values for 180 Day Heart Girths of S x H Females ••..•.•••.•• 226
U8 . Data Used and Calculated H Values for 180 Day Heart Girths of S x G Females 227
v± LIST OF TABLES (continued)
Table Page
U9« Heritability Estimate for Mammary Gland Grade in Holsteins ...... 2 3k
50• Data Used and Calculated II Values for Mammary Gland Grades of G x H Females 23?
5>1« Analysis of Variance of II Values for Mammary Gland Grades of G x H Females 236
52. Regression of Weight on Age at First Freshening • • 239
53• Heritability Estimates For Weight at First Freshening ...... • 2Jjl
5U. Data Used and Calculated H Values for Weights at First Freshening of G x H Females 2lj.2
55* Analysis of Variance of H Values for Weights at First Freshening of G x H Females ...... 2ii3
56. Data Used and Calculated II Values for Weights at First Freshening of H x G Females ...... 2Uij.
57* Analysis of Variance of II Values for Weights at First Freshening of H x G Females ...... 2i;5
vii LIST OF APPENDIX TABLES
Table Pag©
1* Data on Birth Weights of G x H Females . • . « , . . 2£6
2. Data on Birth Weights of H x G Females • . • . . 2$ 9
3• Data on Birth Weights of S x H Females • ••••• 262
i*. Data on Birth Weights of S x G Females ...... 263
5« Data on Birth Weights of G x H Males ...... 26h
6a Data on Birth Weights of H x G Males ...... 267
fa Data on Birth Weights of S x H Males . . . . • • 269
8 * Data on Birth Weights of S x G Males »••••» 270
9a Data on Gestation Lengths of G x H Females « • * * 271
10. Data on Gestation Lengths of H x G Females • . 2?U
11 • Data on Gestation Lengths of S x H Females • • . . 277
12* Data on Gestation Lengths of S x G Females • . • • 278
13• Data on Gestation Lengths of H x J Females • • • • 279 lU. Data on Gestation Lengths of G x H Males • • . • 260
15* Data on Gestation Lengths of H x G Males • • • « 283
16* Data on Gestation Lengths of S x H Males • • • • 28£
17. Data on Gestation Lengths of S x G Males • • . . 287
18. Data on Weights of G x H Females ...... 288
19* Data on Weights of H x G Females ...... 290
20. Data on Weights of S x H Females ..».•••• 291
21. Data on Weights of S x G Females ...... 292
22. Data on Heart Girths of G x H Females ...... 293
23. Data on Heart Girths of H x G F e m a l e s ...... 296
21;• Data on Heart Girths of S x H Females ...... 298
viii LIST OF APPENDIX TABLES (continued)
Table Page
2S>. Data on Heart Girths of S x G F e m a l e s ...... 299
26. Data on Mammary Gland Grades of G x H Females » • 300
27. Data on Freshening Weights of G x H Females . » • 301
28. Data on Freshening Weights of H x G Females . • • 303
ix INTRODUCTION
This study deals with an analysis of data accumulated on the crossbred dairy herd at the South Carolina Agricultural Experiment
Station, Clemson Agricultural College, Clemson, S. C© This herd was started by Professor J. P. LaMaster, in 1936, by making reciprocal crosses between animals of the Guernsey and Holstein breeds. Later crosses were made between animals of other breeds*
The objective in starting the herd was to provide material for study by students in genetics classes.
In its early history the crossbred herd was not considered as a research project; hovrever, the data obtained are comparable to those obtained on the purebred cattle at the station during that time. The crossbred and purebred animals have been handled in one large herd under the same environmental conditions. In November 19^7 the South
Carolina Agricultural Experiment Station activated research project
S* C* 7 under the Research and Marketing Regional Dairy Cattle Breed ing Project S-3, and the crossbred herd was included in this project*
The crossing of animals of different breeds in certain classes of live stock has proved beneficial, especially in those classes kept for meat production [win't,ers (157) s Phillips et al. (108) and
Baker and Quesenberry (2)j , While purebred animals of the different breeds of dairy cattle have been crossed in experiments for a period of 50 years, the data available are not sufficient to appraise accurately the value of such crossing, as brought out in
a review by Robertson (12U)• The importance of the data obtained on the crossbred herd at the South Carolina Experiment Station and of any conclusions which may be drawn from these data has increased in recent years because
of the interest in the results obtained by the Bureau of Dairy
Industry (now in Animal Husbandry Research Division) in crossbreeding
dairy cattle, and the activation of several crossbreeding experiments.
Any benefit accruing from crossbreeding would be an example
of heterosis as generally understood. Therefore, this concept will
be taken up first in the review of literature. ■ KSVISIV OF LITERATURE \ . ’• * '* o ' e • c - * The' jffeahipg of Heterosis
Heterosis or hybrid vigor is the increased liveability, growth, fertility or productiveness, resulting from the mating of distantly related plants and animals,, such as varieties, breeds, species, and subgenera. The phenomena are not new.. The classic example of hybrid vigor in animals is the mule, obtained by crossing the ass . and horse. Castle (19) stated that this cross has been made since early Greek and Roman times. East (39) stated that the vigorous" growth which so frequently accompanies hybridization has puzzled biologists for two centuries*
Shull in 1908 (128) reported on his investigations with corn*
He had crossed and self-fertilized lines of as nearly equal parentage as possible. In the self-fertilized rows the plants were smaller, had weaker stalks with fewer ears, and the ears were dialler. The superiority of the cross-fertilized plants vias described in such terms as "greater vigor" and "more vigorous*" East (38). stated that the word vigor has been used as an inclusive term to describe all. the differences between inbred and. crossbred plants.
Shull (131) coined the ward heterosis in 191^ to replace the. word hetero zygosis; however, it was chosen in the same spirit (132) as Johannsen1s word gene in that it should be free from every
hypothesis. Shull (132) stated that heterosis and hybrid vigor mean the same thing and that heterosis should not be considered
. c " more fundamental than hybrid vigor. He considered that the word.,
heterosis wajs- correctly defined xo the Me-rriam-Webster new » ° •* International Dictionary, Second Edition. It defines heterosis as
"the greater vigor or capacity for growth frequently displayed by crossbred animals or plants as compared with those resulting from inbreeding." Hybrid vigor is defined as "vigor resulting from hybrid!ty specifically heterosis."
East (39) stated that heterosis is more aptly described by the old term hybrid vigor and that it is something which usually concerns the plant or the animal as a whole. Its effect can be compared with the effect on a plant of the addition of a balanced fertilizer to the soil, or to feeding a more adequate and more chemically complete diet to the animal.
Dobzhansky (33) took issue with the assumption, often implied in discussions of heterosis, that a hybrid which is larger or more rapidly,growing than its parents is also more vigorous. This objection was based on the idea that there is a point which is optimal for each character. When increases are above the optima, losses rather than gains of adaptive value occur.
Castle (19) discussed the hybrid vigor often shown when animals of two species are crossed. He pointed out that if the crossbreds are mated with each other, the increased vigor tends to disappear.
Because increased vigor is sometimes found in crosses between different breeds or varieties of the same species, he thought it might better be called crossbred vigor.
According to Brieger (9) heterosis is characterized by an
increase of the mean value for quantitative character differences,
when hybrid means are compared with those of their offspring
obtained by selfing or any other method resulting in close 5 inbreeding. He recognized that heterosis may cause an increase of means of hybrids over their parents. Brieger maintained that the most important feature of heterosis is the impossibility of main taining hybrid vigor in the offspring obtained by any kind of in- breeding .
Dobzhansky (33? 3U) stated that the terms hybrid vigor and heterosis are common names for a group of scarcely related phenomena.
Two different kinds of heterosis in Drosophilia pseudobscura are known and understood. The first kind results from the presence in populations of deleterious recessive mutant genes sheltered by their superior dominant alleles. The accumulation of these deleterious genes is a by-product of the mutation process. Dobzhansky called this euheterosis the simplest kind of true heterosis. The second kind of true heterosis is balanced heterosis, which is due to a special class of mutations and gene combinations that cause heterozygotes to have a higher adaptive value or more usefulness than is found in the corresponding homozygotes in the manner of the overdominance hypothesis postulated by Hull (6 7 ? 68). Dobzhansky stated that both kinds are normal adaptive states which have resulted in outbred sexual species through natural or artificial selection.
The heterotic state can be disrupted by sudden inbreeding and can be restored by crossing the inbred lines. Dobzhansky applied the term luxuriance to those hybrids between species, neither of which are inbred, which exceed the parents in some quality. It is also observed
in some hybrids between normally self-fertilizing species, races, or
strains. From the evolutionary standpoint, Dobzhansky described
luxuriance as an accidental condition brought about by complementary action of genes found in the parents*
Gowen (58) crossed two inbred races of Drosophila melanogaster which averaged 389 and 1,000 eggs respectively. The hybrids produced an average of 2,03U eggs. The hybrids individually were not better than the best individuals of the inbred races, but all hybrids came nearer to reaching a high level of production* Gowen stated that this is the "essence of hybrid vigor."
Richey (120) stated that hybrid vigor may be defined as the excess vigor of a hybrid over the average vigor of its parents.
Later Richey (119) stated that individual hybrid corn plants are not superior to the best plants of the open-pollinated varieties.
The larger yields of hybrids are the result of the superior modal performance of the hybrids. The statements of Gowen and Richey
indicate that they had a similar conception of the meaning of the
terms heterosis and hybrid vigor.
Powers (110, 111) maintained that in order to understand
heterosis, it must be considered as a phase of quantitative
inheritance, the same as are dominance and partial dominance. He
objected to always associating heterosis TJith the beneficial or more
desirable character, and maintained that at times a distinction is
desirable. He suggested that the term heterosis be used in the usual
sense and non-beneficial heterosis be used when the F]_ hybrid exhibits
heterosis for the less desirable of two contrasted characters.
Shull (132) did not like the use of the tern heterosis in the negative,
because he thought there was no relationship to the phenomena for
which the term was originally proposed.
Lambert (83)> as chairman of the committee oh Investigations of the American Society of Animal Production in 19U0, submitted the following definition of heterosis: “Superiority of the progeny over either parent as the result of crossing# This applies to the progeny resulting from the crossing of strains, varieties, breeds or species.11
At present there is no definition of heterosis which is accept able to all workers in the field of genetics. The differences in the definition are based on two points: the first being on how extensive a plant or animal should show heterosis of the various parts, and the second on whether the mean of the hybrids should be
superior to the mean of the parents, or whether it should be
superior to the best parent. Powers (110, 111) is an exception; he thought that heterosis may also be negative.
East (39) stated that heterosis was something that concerned the organism as a whole. Richey (120) did not agree. He thought
that even though only one character in a plant showed an increase,
it should be considered as a case of heterosis.
According to Brieger (9) heterosis does not affect individuals
as a whole but the expression of each character, independently of
the other characters. Coffman and Davis (22) concluded that heterosis
was specific in oats. In some crosses it was observed in a few
plant parts, and in other crosses in many plant parts.
Luckwill (8?) came to the same conclusion in a study of heterosis
of plant parts in tomatoes during the flowering period, luckwill grew
a population of F-j_ plants side by side with populations of the two
parents. Heterosis did not involve a general increase in vegetative
vigor in the generation but was a specific effect which was 8 manifested to different degrees in the various organs of the plant*
Castle (17) measured heterosis in dairy cattle by comparing the
average of the F^ generation with the average of the parental lines*
According to Gowen (6l) experience has defined hybrid vigor as the
superiority of the hybrid over the better parent, whereas Hayes (6 I4.)
recognized that both the mean of the parents and the better of the
parents are being used for comparison with the hybrid*
Winters (157) stated that Lambert’s (83) definition is satis
factory when it is possible to make an over-all measure of vigor.
Winters agreed that the crossbred should show more vigor than the
most vigorous parent to be considered an example of hybrid vigor*
However, he pointed out that it is seldom possible to obtain a satis
factory over-all measure of vigor* Winters stated that when vigor is
broken down into its various components, Lambert's definition becomes
defective* He thought this was clearly shown by Powers (111) in a
study of heterosis in tomatoes. Powers made a cross between inbred
tomato (Lycopersicon) lines and found that the F-^ generation had
means for ripe fruit and size which were less than the means of the
two parents. However, the yield of fruit, in pounds by the F]_, was
greater than the yield of either parent*
Lush (91) stated that to restrict the definition of heterosis
to cases in which the crossbreds excel the larger or more vigorous
parent complicates the formulas needlessly. He thought that most of
the apparent correspondence between such a definition and the
practical use of heterosis disappears when the facts with respect to
single characteristics have to be combined into facts with respect
to net merit* Lush pointed out that this procedure is necessary 9 when a practical use of heterosis is to be made#
Winters et al. (l£8) and Sierk and Winters (133) pointed out that the practical question is not how much advantage crossbred hogs show over their inbred parents but how they compare in performance with hogi? produced by conventional methods.
The Hypotheses Advanced to Explain Heterosis
Several hypotheses for the explanation of heterosis have been proposed, but as Shull (132) pointed out, they are not "mutually exclusive." In order to maintain a continuity of thought, each hypothesis will be discussed separately. The tern heterosis will be used as synonymous with hybrid vigor.
The Hypothesis of Heterozygosity
Shull (128, 12?) is credited with proposing this hypothesis, but East (3If 38) also had much to do with its development. Shull had crossed and self-fertilized lines of corn of as nearly equal parentage as possible. The plants from the self-fertilized seed had weaker stalks with fewer ears, and the ears were smaller by comparison with the progeny of a normally crossbred plant derived from the same source* When plants from two inbred lines were crossed, the progeny
showed as much vigor, size, and productiveness as the progeny of a normally crossbred plant. Shull realized that the smaller size and inferior yielding ability of inbred lines was not due to inbreeding
as such but to the fact that inbreeding made them more homozygous.
He then proposed that heterozygosis had a stimulating effect on the
plant grown from seed obtained by crossing inbred lines. East (37)
stated that Shull's (128) ideas on inbreeding and crossbreeding were substaniated by his own data. Shull (130) based his hypothesis on the assumption that the degree of vigor was correlated with the number of genes in which the organism was heterozygous, but that this correlation was not perfect. East and Hayes (1*0) examined the
evidence available on the role of heterozygosis in plant breeding.
They had found that the self-fertilization of c o m from one to seven
generations resulted in a loss of vegetative vigor, but that if two
inbred lines %*are crossed the F^ showed normal vigor. Like Shull,
they thought that vigor was increased with increased heterozygosity.
In 19lU Shull (131) proposed that the word heterosis be adopted to
describe the situation in which heterozygosity caused the organism
to be better than its parents in certain characteristics. Shull did
not think the differences in the gametes uniting to form an individual
showing heterosis need be Mendelian in their inheritance, and for this
reason he suggested the word heterosis. Richey (121) considered this
explanation strictly non-Mendelian. He maintained that except for
the fact that vigor increases more or less proportionately to changes
in heterozygosity, the explanation appeared to have no supporting
evidence. Richey considered Shull's hypothesis as one of
"physiologic stimulation." In 1916 Castle and Wright (20) reported
on crosses made between males of the wild species of Cavy, Cavia
cutleri Eennett, and females of two inbred races of guinea pigs,
designated E and C. The adult cutleri females averaged UOO grams and
the males 1*20 grams in weight. The males and females of races B and C
averaged about 800 grams. The F^_ males and females showed heterosis
by being heavier than those of either parent race. A cross between a
mala weighing 1,200 grams, of the Arequipa race of guinea pigs from Peru, with females of race B produced males that weighed approximately the same. Castle reasoned that the F-^'s from these crosses should have been intermediate in size between parent races* The difference between the expected and actual results was attributed to a physiological growth stimulus, brought about through the union of
gametes from dissimilar races. Castle (18) attempted to explain the
susceptibility to tumor of F-^ mice, produced by mating Japanese Waltz
ing mice and the house mouse, by the heterozygous condition. The
Japanese Waltzing mouse is susceptible, whereas the house mouse is
immune to a tumor which originated in the Japanese Waltzing mouse*
When these mice, which according to Castle are probably domestic
derivations of two different wild species, are crossed, the F^'s are
more fertile, vigorous, and long-lived than either parent variety.
They are as susceptible to the tumor as the Japanese Waltzing mice,
and it even grows faster in them. It is rare for an F 2 mouse to be
susceptible to the tumor. Susceptibility is thought to depend on a
number of independent genes. All of these genes need to be present
or the animal is not susceptible. The F-^ receives a complete set of
gene3 from the Japanese Waltzing parent and is consequently suscepti
ble. Owing to their independence (located in different chromosomes),
they are rarely combined in the F2 animals, thus few F2 individuals
are susceptible. Castle interpreted the accelerated growth of the
tumor in the a result of the same stimulus that speeds up metabolic
processes in crossbred individuals, and thought the facts favored the
hypothesis of heterozygosity as a cause of heterosis, rather than the
linked dominant gene hypothesis to be discussed later. His reasoning
was that there are no genes in the house mouse which w i l l bring about •growth of the tumor, so dominant genes are not present. The
increased growth in the F-^ must therefore be due to heterozygosity
and hot to any dominant genes contributed by the house mouse.
Livesay (8 6 ) studied heterosis in crosses made between one inbred
strain of rats and two other inbred strains of rats (Rattus
norvegicus). The character studied was growth as measured by weight
at ninety days of age. Livesay compared the F-^ males and females
with animals of the same sex from the inbred families used in making
the cross. In both crosses, animals of each sex were heavier than
animals of the inbred parental strains. The males and females of
inbred line weighed 1 7 3 . 0 and 137*8 grams at ninety days of age.
The males and females of inbred line S2 weighed 131.9 and 1CU.3
grams, whereas the male and female progeny of the cross S-^ x Sg
weighed 209.2 and 1$9.2 grams respectively. Males and females of
inbred line S3 weighed 203.9 and 15>6«3 grams, whereas males and
females of the cross S-^ x weighed 2 1 8 .U and I6J4..3 grams respective
ly* There was a distinct loss of size b y the Fg rats when F]_ rats
were crossed. Randolph (116) studied the effects of heterozygosis on
tetraploids in maize developed from inbred and non-inbred strains.
Tetraploids from inbred lines showed decreases in vigor and fertility,
whereas those from non-inbred lines were as vigorous as or more
vigorous than the diploid parent, and were highly fertile. The
reduction of vigor, during the inbreeding process in both the diploid
and the tetrapolid, progressed at essentially the same rate as
reduction in heterozygosity. Renewed vigor accompanied the increasing
•of heterozygosity through the recombination of genetically different ' ‘ ^00. ‘ inbreds*. Randolph concluded that the effect of doubling the homozygous genes at each locus in the tetraploid derived from inbred s.,
and the absence of this effect in heterozygous tetraploids suggested
that homozygosity is a significant cause of the reduction in vigor
■which accompanies inbreeding. Conversely, heterozygosity in itself may be responsible for much of the heterosis exhibited by hybrids.
Shull (128, I29j» 131) > East (37) > East and Hayes (UO), and Castle (19)
all showed reluctance to put heterosis on a purely genic basis. There
has always been the possibility that a certain physiological stimula
tion results from the uniting of unlike gametes and the way was left
open for proving it to be a fact. Gowen ($8 ), and Gowen et al. (6 0 )
have reported on experiments with Drosophila, which were designed to
determine the relative importance of genes and cytoplasm in heterosis*
The original stock (60) had been random mated for 10 generations,
then inbred for 37 generations by brother and sister mating. At this
time the progeny were divided at random into three lots. One of the
lots was divided into two lines, each of which was bred for ten
generations by random mating. These lines were called "random” bred.
The second of the three lots was subdivided into 35 new inbred
strains, each of which was continued b y brother' and sister mating
for another ten generations. The third lot of flies was bred by an
outcross technique so as to produce progeny homozygous for the first,
second, and third chromosomes. Eighteen such strains were produced,
which ware designated "homozygous.” The cytoplasm of a homozygous
strain was not that of the original inbred race but that of the race
it was mated to in order to produce the homozygous strain. The
cytoplasm of the second race was heterogenous as it had been
maintained by outcrossing. If heterosis is due to cytoplasmic differences, the homozygous strains with their heterogenous cyto plasm should have shown more vigor and yielding ability than the
iribredsj however, if heterosis is due to gene differences within loci
the inbreds with the greater heterozygosity should have shown more
production than the homozygous strains. Egg production for five
consecutive days was chosen to measure the effect of the breeding
systems* Twenty females from each system of breeding were tested
in two different experiments. The random bred strain which was most
heterozygous had the highest yield. The closely inbred strain with
presumably greater homogenity was intermediate, and the homozygous
strain had the lowest production* It was concluded that heterosis is
based on differences in genic interaction between alleles and their
reaction products, rather than stimulation resulting from the union
of unlike gametes. Gowen et al. (60) conducted further experiments
comparing inbreeding and outcrossing to make homozygous types.
Twenty-four tests were made and in 20 the homozygous laid fewer eggs
than its corresponding inbred strain. In no case was the homozygous
egg production significantly larger than the inbred. It was concluded
that the general trend of these data confiimed those of the earlier
experiments. Straus and Gowen (lUl) crossed two inbred strains of
Drosophila melanogaster, of which the crossbreds showed an increase
i*1 eSg production of almost 1 0 0 per cent above the average of the
parents* All possible homozygous and heterozygous combinations of
the first three chromosomes were obtained and tested for egg produc
tion. The relationship between vigor as measured by egg production
and chromosomal heterozygosis was linear. The individual chromo
somes contributed heterosis in proportion to their active length as measured by band number in the salivary chromosomes and crossover units, no interactions or combination effects being detected.
Gowen (59) presented results of experiments with Drosophila which indicate that heterosis is the result of additive gene action. The breeding program followed was to obtain reciprocal crossed flies from several inbred lines, then backcross the hybrids to their parental inbreds for several generations with selection. The results of these studies showed that additive gene action accounted for most of the increase in yield by the hybrids. Dominance and complementary gene action accounted for only a small proportion of the variance in the different groups. The genes causing heterosis appeared in all chromosomes and were distributed according to the quantity of chromatin material.
Dominance and Dominance of Linked Genes
Bruce (10) in November, 1910, presented a Mendelian explanation of hybrid vigor in purely mathematical terms. He concluded that the total number of dominant genes is greater in a hybrid population than in either parental population when the parental populations are breeding true to their means. Assuming that dominance is positively
correlated with vigor, Bruce stated that the crossing of two pure breeds produces a mean vigor greater than the collective mean vigor
of the parent breeds. Jones (73) stated that Bruce did not show why
the presence of a greater number of dominant genes brought about an
increase in growth, nor did he show why it was that all the dominant
genes could rarely or never be accumulated in certain individuals and
races which would therefore show no reduction in vigor when inbred. Brieger (9) stated that Bruce missed the essential point of the cominance hypothesis, which is the covering up in the hybrids of all or most recessive genes by their respective dominant alleles, con tributed by one or the other of the two parents* Brieger maintained
that in order to explain heterosis the hybrid population should
contain less homozygous recessives than either parent population*
In the same month that Bruce’s article appeared, an article by Keeble
and Pellew (7 9 ) was published which has also become important from
the standpoint of an explanation of heterosis* They studied the
inheritance of stature in peas (Pisum sativum)« Two varieties which
stood five to six feet produced F-^ progeny, seven to eight feet in
height* The Fg segregated in a 9*3:3:1 ratio* The parents differed
in two characters, length of internode and thickness of stem, each
parent being dominant for one and recessive for the other. Keeble and
Pellew explained the height of the F^ as re stilting from the two
dominant genes. East and Hayes (lj.0) disagreed with this interpreta
tion, maintaining that "tallness" and "dwarfness" were quite
different from t he ordinary transmissible size differences among
plant varieties. They thought heterosis was too universal among
crosses to be explained on the basis of transmissible size differences*
East and Hayes also raised one of the two objections which prevented
the Keeble and Pellew interpretation from being adopted as an explana
tion of heterosis. It was based on the fact that size genes usually
lack dominance or at best show incomplete dominance* They thought
the vigor of the F^_ hybrid generation theoretically had nothing to do
with these facts. The reason was that the increased vigor shown as
height in the F-^ generation could not be obtained as a homozygous segregate in later generations, which should be possible if it were due to dominance* The other important objection to the Keeble and
Pellew interpretation, raised by Emerson and East (lUt) , was that if heterosis is due to dominance, the distribution of F 2 individuals would be asymmetrical in respect to characters in which heterosis was shown in the generation. Emerson and East had studied height in four different c o m crosses. In three of the crosses, the F^ plants were almost ap tall as the tall parent, whereas in the fourth cross the F-^ was taller than the mean of the parents. Snerson and
East attributed this increase in height to increased vigor from heterozygosis, rather than dominance of tallness over shortness.
They arrived at this conclusion because in every case the mean height of the Fg plants was half-way between the heights of the parents, and there was a lack of skewness in the F^ frequency distributions. The data of Keeble and Pellew showed that the F2 segregated into groups of 9:3*3*! on the basis of height. Jones (72) stated that in the case of any size character similar to height in peas with any number of genes, the Fg would give an asymmetrical distribution. This was assuming that the individual with the greatest number of dominant
genes would show the greatest development of the character. Accord
ing to Jones the distributions of the F2 in the crosses described by
Bnerson and East, where heterosis was shown in the F-^, would all be
considered normal frequency distributions. In order to get around
the objections to Keeble and Pellew’s interpretation, Jones (72)
added the idea that the dominant genes are linked. In doing so he
developed the hypothesis which many consider the explanation of
heterosis. Jones’s hypothesis was based on a series of assumptions; some were supported by experimental evidence, others were theoreti cal. The assumptions were as follows: (1) Many genes and different
sets of genes are concerned with the development of characters.
(2) No one variety has all the favorable or unfavorable genes. (3) If
the genes for favorable characters are dominant over genes for unfavor
able characters, complete dominance is not necessary for the F-^ to
exceed the average of the parents. Only in the can the maximum
number of different genes be accumulated in any one individual.
(U) Owing to linkage, no individual in later generations could have more genes in the homozygous condition than were present in the
parents if the genes were distributed uniformly in all the chromosome
pairs. Jones recognized possible exceptions to this point. He
presented a hypothetical case in which two homozygous varieties of
plants, containing different sets of genes, attained the same develop
ment for a character. This development was taken as six units, two
being contributed by each of three chromosome pairs. Each chromosome
pair carried three pairs of genes, each pair different in its contri
bution to the development of the plant. It was assumed that one of
each pair of genes iras completely dominant to the other. It was shown
that because the F^_ contained 18 differeht genes (in the In condition),
it would develop to twice the extent of either parent whereas the
parents had only nine (in the 2n homozygous condition). The F , on
selfing or breeding the F-^, would show a symmetrical distribution and
this would hold, regardless of the number of chromosomes concerned.
The mean development of the was nine units, which was just half as
much as the was above the parents.
The development attained by any individual in the Fg was correlated with the number of heterozygous genes present. Jones recognized that the assumption of complete dominance in the hypothetical illustration was not justified, since the interpretation of quantitative characters is often based on the assumption that genes
in the In condition have just half the effect that they have in the
2n condition. He concluded that to explain heterosis on the basis of dominance it was necessary to assume that some factors in the In
condition have more than one-half the effect they have in the 2n
condition. Jones pointed out that many genes for abnormal characters
exist in naturally cross-pollinated species, and that they are
recessive to the genes for the normal condition. In a cross, normal
F^_ plants are produced because the gene for normal comes from one of
the parents, and this enables the to attain greater development.
According to Jones this effect is heterosis. Jones pointed out that
through crossing-over occurring in heterozygotes, all, or a large
number of desirable characters, could possibly be combined in one
individual, but such a condition would be rare. Collins (27) compared
the F^_ ajad F£ generations to see if the objection made by East and
Hayes (I4.O) to the dominance hypothesis was valid. He showed that with
a large number of genes affecting vigor it would be impossible in
practice to obtain homozygous individuals having the vigor of the
first generation. Lush (91) stated that it is not necessary to use
linkage to explain why segregates containing only dominant genes are
not found, since a large number of independent genes would produce
the same result. Collins (2?) also considered the objection made by
Emerson and East (Uii) to the dominance hypothesis. He found that when
the number of pairs of genes is increased, skewness becomes less apparent and that popvQ.ati.ons of 5>00 individuals conform to the normal frequency curve as closely as would be expected. He concluded that the assumption of linkage, while not impossible, was not needed to
explain heterosis, since neither of the objections which it was framed
to meet had any foundation• Collins considered it unfortunate that
Jones (72) attributed heterosis to the accumulation of dominant growth
genes instead of placing emphasis on the suppression of deleterious
recessive genes. Collins was sure that the suppression of such genes
in the F-^ explained heterosis, and that the reappearance of characters
due to these genes was the only factor in the decline of vigor that
follows inbreeding. East (39) did not think that deleterious
recessives were important in the solution of the problem of hetero
sis. His reason was that after inbreeding a line for several years
the deleterious recessives have been largely eliminated. Yet these
purified lines exhibit as much or more heterosis when combined with
other inbred lines as they did when segregating defective recessives.
However, Gowen (6 l) reported that inbred races of Drosophila
frequently contain, or soon attain, mechanisms which slow down or
prevent reaching complete homozygosis through continued close
inbreeding. Gowen concluded that mutation as a heterosis mechanism
may be of more importance than has been thought in the past.
Richey (121) did not think that the suppression of defective recessives
was important in heterosis which results from crossing two inbred
lines of corn. But he did not exclude the influence of the suppression
of minor deleterious recessive genes, which may occur in large numbers
with imperceptible individual effects. Whaley (15>1) stated that the
favorable effects of many dominant alleles may be due to the 21
accumulation in populations of deleterious recessive mutations. If the effects of the recessives are not too drastic, many can be accumulated,
Sierk and Winters (133) thought it reasonable to assume that some of the heterosis shown by F^ pigs from crosses of inbred lines was due to the suppression of unfavorable recessives, Wright (l6l), in reporting on the inbreeding and crossbreeding experiments conducted by the Bureau of Animal Industry with guinea pigs, indicated that he was partial to the dominance hypothesis. In this experiment inbred lines were developed and then crossed. A control stock had also been maintained by mating animals less closely related than second cousins, Wright compared animals of each line: control, inbred, and crossbred by the use of the actual average or an index, with the estimated record of the total inbred stock produced simultaneously. Wright found that crosses between different inbred families resulted in animals showing an improvement over both parental stocks in every respect. For example, adult weight was increased about 12 per cent and resistance to tuber culosis 20 per cent. Wright interpreted this as the result of each line supplying some dominant genes lacking in the other line, dominance or even imperfect dominance for each character being b u i l t up into a pronounced improvement over both parent stocks. A certain portion of the increase in vigor in the first cross between inbred families was maintained on the resumption of random mating. One-half of the increase being maintained in stock founded on two inbred lines, two-thirds in stock based on three lines, three-fourths when based on four lines, and four-fifths when based on five lines, Eaton (Ul) published a more complete analysis of the Bureau of Animal Industry experiments with guinea pigs. He worked with the same inbred families (five in number) and control strain B as did Wright,
Reciprocal crosses "were made between some of the inbred families.
In some cases the F^_ was mated to animals of a third inbred line to produce three-way crossbreds. The crossbreds were compared with each of the inbred parental lines and the control strain. He also rated the inbreds and crossbreds on the basis of 100 for the control
strain B for various measures of fertility, growth, and mortality.
The crossbreds had to be better than either parental strain before
Eaton considered that heterosis had been shown. Significance of the
differences was determined statistically. The control stock and the
inbred families differed in the characters studied, with no one
strain superior in all of them. The different crossbreds also varied
in these characters. When strains of high and low fertility were
crossed, the crossbreds were usually better than the poorer parent
but not as good as the better parent. This also held for growth.
The greatest improvement occurred when two strains medium for a
character were crossed. In most cases the crossbreds showed more
viability. Greater fertility and viability were obtained when three
inbred families were in a cross. Eaton assumed that this was due to
the large number of favorable genes being brought together from three
inbred families. Richey and Sprague (119) in 1931 published evidence
in support of the dominance hypothesis. This evidence was obtained
in an experiment on "convergent improvement" as a means of improving
selfed lines of corn without interfering with their behavior in
hybrid combination. In convergent improvement two selfed lines of
corn that produce a high yielding cross are selected. Then the
dominant favorable genes carried by one line, but lacking in the other, are added to the line that does not have them. This is accomplished by crossing, then backcrossing to one parent for several generations, at the same time selecting to retain the favorable dominant genes of the non-recurrent parent. Each original parent is used as a recurrent parent. Selection is carried on within selfed lines to fix the added genes. The operation is then repeated, using the recovered lines as foundation stocks. Richey and Sprague contended that success in such a program was possible only if the interaction of dominant favorable genes was the cause of heterosis, because the recovered lines were more nearly like each other, and crosses between them would be less heterozygous. They found that in all cases the crosses between the recovered lines were more productive than the crosses from the original parents. Richey and
Sprague concluded that the excess yields of crosses from the recover ed lines were due to dominant favorable genes retained by selection
during backcrossing. Richey (121) pointed out that Richey and
Sprague (119) suggested that genes of partial dominance were involved
as well as those of complete dominance. Murphy (101) used the
convergent improvement method of breeding with four inbred lines of
com. Marked improvement was made in the recovered lines in vigor
and other characters in instances where the original lines lacked
these characters. A majority of the crosses between the recovered
lines and the recurrent parent had yields significantly higher than
the original recurrent parent. Some of the recovered lines yielded
as well as the original F-^ cross when tested in crosses with the
non-recurrent parent® Single crosses between recovered lines were
made which yielded significantly more than the original F^ cross® Richey (121) stated that Murphy’s results confirmed the conclusions of Richey and Sprague (119; that the probable cause of heterosis is the interaction of dominant and partially dominant favorable growth genes. Karper and Quiriby (78) studied heterosis in crosses of the sorghums, (Sorghum vulgare, pars.) milo, kafir, Hegari, feterita, Kaoliang sorgo, and broomcorn. All of the hybrids were more vigorous than either of the parents, with heterosis most apparent in increased vegetative growth and extreme lateness of maturity. However, there were degrees of heterosis, which they thought were due to differences in the number of dominant genes that were favorable to growth. East (39) suggested that the linked
gene part rather than the dominance idea should be considered the main basis of Jones’s (72) hypothesis. Luckwill (88) made a genetic
analysis of heterosis in tomatoes (Lycopersicum). He grew populations
of twelve first generation hybrids and seven inbred parental lines
under unifoim conditions. The reason for carrying out the experiment
was to determine what particular type of hybrid exhibited heterosis,
at what stage in the life history heterosis was first manifested,
and whether there was any difference in the size of reciprocal
hybrids. Luckwill used wet and dry weight as the measure for compar
ing the plants. Heterosis was considered as being demonstrated when
the mean of the hybrid exceeded the larger of the parental means, and
the difference was statistically significant by analysis of variance.
If the mean of the hybrid was significantly less than the mean of its
larger parent, or if there was no significant difference between the
two means, the hybrid was then compared with the smaller parent to
determine whether size had been inherited in a dominant or inter 25 mediate manner. Luckwill used geometric rather than arithmetic means of the weight data. He found that in several cases the hybrids
showed heterosis at one stage of growth but not at another. Sight hybrids showed weight heterosis., but only three of them showed height heterosis. Three did not show heterosis for weight but did show it for height. In the remaining hybrids, except one, height was inherit
ed as a dominant from the tall parent. The one exception was inter mediate between its parents. In three crosses of varieties of
L. esculentum, two of them being reciprocals of two varieties,
Luckwill accounted for the increased size of the hybrid on the basis
of complementary action of the dominant allelomorphs of two major
growth genes D and Br. Each parent did not have one of the genes
necessary for maximum growth (either D or Br.), but the hybrids had
both genes and since these genes were completely dominant over their
recessive allelomorphs, the hybrids showed heterosis. Luckwill
thought these examples of heterosis were similar to the one reported
by Keeble and Pellew (79), and were simple applications of Jones*s
(72) hypothesis. He thought that heterosis in interspecific hybrids
required another genetic interpretation which will be discussed
later. Powers (110) studied the problem of heterosis in quantitative
characters in crosses between varieties of two species of tomatoes
(lycopersicon)• He considered that heterosis was shown when the
expression of the character in the F-^ generation was either greater
or less than the magnitude of the character in either parent* Where
the generation was the same as one of the parents, and there was
a significant difference between the parents for the character,
dominance was thought to be shown. When the phenotypic expression in 26 the F^_ generation was between the two parents but not exactly intermediate (arithmetically), it was considered to be a case of partial dominance* Powers used a test of significance and considered differences having probability values less than 5 per cent as significant* Powers studied the number of days it took from the time the seed was planted until the first fruit completely changed color*
The Danmark and Johannisfeuer varieties of lycopersicon esculentum were crossed, and parent, F^, ^ and backcross generations to each parent grown* In 1938 there were no significant differences between the means, and a smaller nlimber of days for change of color of the fruit was completely dominant* In 1939 the means of the F^ generation and the backcross to Johannisfeuer were significantly smaller than the means of Johannisfeuer and Danmark* Powers concluded that smaller number of days to first complete change of color showed heterosis, and since the genotypes were constant for 1938 and 1939 that the environment as represented by years determined whether the character should exhibit hetearosis or dominance* Powers compared the means for the days between the first fruit set to the first complete change of color of any fruit for the above cross* The means of all progenies were between the means of the two parents* Smaller number of days for the character was partially dominant* In a cross between the Johannisfeuer variety and the Red Currant variety of lycopersicon pimpinellifolium, the means for the above character of the F^, the backcross to Johannisfeuer and the F2 generations were
smaller than the mean of either parent. The differences involving the mean of the F^ were statistically significant and heterosis was
shown for the character. As the environmental influences had been controlled, it was concluded that whether the character exhibited
heterosis or dominance was determined by the genotype. Powers maintained that the results supported the supposition that heterosis
and dominance represent degrees of identical phenomena, and are
dependent upon the same "physiological genetic processes," Powers
(111) in 19hh proposed an expansion of Jones's hypothesis. Powers
considered the hypothesis to be as follows: (1) "A large number of
genes are responsible for the differentiation of most quantitative
characters and, (2) those genes favorable to the production of the
desirable quantitative character are at least partially dominant,"
Powers presented data on the number of ripe fruit per plant, size
Of fruit and yield of ripe fruit per plant for certain F^ tomato
(lycopersicon) hybrids, and their parental inbred lines. The number
of ripe fruit per plant and size of the fruit are subcharacters of
yield, as the product of the two gives yield* One F^ showed heterosis
for number of ripe fruit per plant and partial dominance for large
size. In another F^, more fruits per plant was dominant and size
showed no dominance. Both few fruits and small size were partially
dominant in the F]_ hybrid 1|102 x UllQ, In all three hybrids, number
and weight of fruit combined to produce heterosis for yield. The
hybrid 1*102 x 1*110 was not only below the better parent for each
character but was also below the means of the parents for the two
characters. However, the F-^ exceeded the high parent in yield by
almost 30 per cent. Powers conclxided that less desirable characters
showing partial dominance may in some instances combine to produce a
third higlily desirable character, which shows heterosis is well
established. Powers stated that partial dominance for the smaller 28 of two contrasted quantitative characters indicates that the genetic phenomena responsible for dominance and heterosis could produce values less than that of either parent* Powers had previously-
reported (110) on a tomato hybrid where the number of fruits for each
centimeter of branch was less than for either parent. He concluded
that heterosis had been exhibited by this character* Powers (111)
thought that Jones's hypothesis should be expanded to take into account
the fact that in some cases the effects of genes are geometrically
cumulative - the reason being that in cases in which the effects of
genes are multiplicative, genes not favorable to an increase of a
quantitative character may show no dominance, or partial dominance,
and still the character itself may show beneficial heterosis.
Powers maintained that the assumption of partial dominance of those
genes favorable to the production of the quantitative character is
not necessary when interallelic interactions of the genes are such
that their effects are multiplicative. Powers (112) furnished further
evidence that dominance and heterosis are different degrees of
expression of the same "physiological genetic phenomena." The charact
ers studied were "weight per locule," "number of locules," and "weight
per fruit" for a Porter x Ponderosa hybrid and parental populations*
On a logarithmic scale, number of locules showed no dominance, weight
per locule heterosis, and the two combined to give partial dominance
for weight per fruit. On the arithmetic scale, the two component
characters united multiplicatively and the F^ showed partial dominance
for greater weight per fruit. Mather (98) stated that an appropriate
scale must be used in representing the degrees of a character, the
most reasonable scale being that on which the average effect of any gene substitution is constant over the range of variation of character expression. According to Mather this demands that the individual effects of the various genes be simply additive on the scale, since non-additiveness of genic effects is a main source of what is teimed metrical bias. An appropriate scale can be constructed by a trans
formation which eliminates or at least minimizes metrical bias*
Mather stated that the examples of heterosis in tomatoes given by
Powers (111) showed metrical bias. Mather agreed that if the method
of analysis used by Powers is accepted, it means, as Powers pointed
out, that dominance in a particular direction is not a necessary
condition for the occurrence of heterosis in that direction. Mather
transformed Power*s data to a logarithmic basis. Yield still showed
heterosis, and dominance was highly correlated with heterosis on the
scale obtained by a transformation which greatly reduced metrical
bias. Mather thought a transformation which eliminated bias would
only emphasize that dominance is connected with heterosis. He
concluded that it would be unwise to modify Jones’s (72) hypothesis
until it has been shown that after metrical bias has been removed,
dominance is absent or opposed in direction to the observed heterosis.
Evidence for dominant genes being the cause of heterosis has come
from investigations with Neurospora. Dodge (35) reported that a
yellow non-conidial dwarf race, Dwarf 16, which by itself grew slowly,
showed a great increase in vigor and production of conidia when grown
with tester races CU and C8 of Neurospora tetraspema. The new
mycelium grew two or three times as fast as those of ch or C8. Dodge
called this increased vigor, heterocaryotic vigor and distinguished
it from individual haploid segregant vigor or heterosis in diploid organisms. Dodge suggested that the hypothesis offered by Robbins
(122) to explain hybrid vigor in tomatoes applied to his results.
Thus, he thought that Dwarf 16 synthesized growth substances which supplemented those synthesized by race Ch (or C8) so that the heterocaryotic mycelium had an optimum of the vitamin-like substances that control growth. Beadle and Coonradt (3), working with mutants, all derived from wild type strains of Neurospora crassa, found that
tills interpretation applied to the results they obtained in growing
pantothenicless and lysineless together. Each of these mutants behaved in crosses as though differentiated from the original wild
type strain by one significant gene. Pantothenicless is unable to
synthesize pantothenic acid but can synthesize lysine and carries
normal alleles of the lysineless gene. lysineless is unable to
synthesize lysine but can synthesize pantothenic acid and carries
normal alleles of the pantothenicless gene. Grown together, the
heterocaryon is able to snythesize both pantothenic acid and lysine,
and show heterosis. Beadle and Coonradt were convinced that the
heterosis shown was the result of genetically complementary nuclei
in a common cytoplasm. The complementary genes in this case were
the genes for the production of the vitamin pantothenic acid and the
amino acid lysine. It was concluded that the physiological basis of
this co-operative gene action is similar to that for heterosis in
diploid organisms. Crow (29, 30) made a mathematical analysis of the
maximum heterosis that might occur under the conditions implied by
the dominance hypothesis. Crow assumed that all genes concerned with
vigor were completely dominant and that in each case the dominant
allele was beneficial and the recessive deleterious. It was assumed 31 that no complex interactions took place among the genes and that crossing over occurred freely. By these assumptions Crow reduced the dominance hypothesis to its simplest form. An individual of maximum vigor would have at least one dominant gene at each gene loci. The difference in actual and theoretical maximum vigor would be determined by the number of homozygous recessive loci. The maximum increase in vigor in crosses would occur if each parent could
supply all the dominant alleles lacking in the other and the hybrid received at least one dominant gene at each locus. Another important assumption made by Crow was that heterosis is measurable in terms of increased selective advantage, the selection being either natural or artificial. This restricts the application to cases in which heterosis goes in the same direction as selection has been acting.
Crow thought such an assumption was valid for yield in field crops and for viability and fertility in Drosophila population studies.
Crow used as an example a large population, mating at random in which the recessive phenotype had a selective disadvantage of _s.
The dominant and recessive phenotypes were surviving and reproducing in the ratio of 1 to 1-s. Genotype AA would have a frequency of jo
and a selective value of 1* Genotype Aa would have a frequency of
2Q and a selective value of 1, whereas values for genotype aa would
be R and 1-s. It was found that the increase in vigor, as measured
by selective advantage, if all deleterious recessives were replaced
by their dominant alleles, would be close to 5 per cent. This is
the greatest improvement in vigor that could occur as a result of
hybridization. Crow stated that the dominance hypothesis cannot,
under the conditions postulated, account for increases of more than 32 a few per cent in vigor. Brieger (9) stated that no conclusive evidence has been presented for either the dominance or heterozygosis
hypothesis as an explanation of heterosis in corn. However, he did
not question but that each hypothesis explained a large number of
facts. He pointed out that the linked dominant gene hypothesis is
intermediate between the original dominance hypothesis proposed by
Bruce (10) and Keeble and Pellew (79) and the heterozygosis hypothesis
proposed by Shull (128)• Brieger studied the theoretical aspects of
heterosis from the point of view of population genetics, using maize
as the subject. He developed formulas for use in deciding whether
the dominance hypothesis or the "heterotic gene interaction"
(heterozygosis) hypothesis is correct. The formulas were based on
the frequency of two alleles A and a at equilibrium in a population,
taking into account selection and mutation. It was assumed that
mutations, either to recessive genes, which reduce viability and are
called subviables, or to heterotic genes, have slowly accumulated
and have reached a population equilibrium governed by the developed
formulas. In considering the dominance hypothesis the survival
values of the homozygous dominant individuals (RA) and of the heter
ozygotes (Aa) were equal, both being unity. The survival value
(Ra) of the homozygous recessive subviable mutants was less than 1.
For the dominance hypothesis, Brieger required that no homozygous
dominants should occur in the balanced random mating population; that
after selfing eveiy individual of the population should be homozygous
for at least one or more loci, and the absence of an asymmetrical
distribution required that every individual of the population be
heterozygous for numerous loci. Brieger thought all these 33 requirements would be fulfilled if one could be sure that any individual obtained by selfing would contain at least one or more subviable mutant genes in the homozygous recessive condition.
Brieger calculated that any plant of the original population must be heterozygous for 28 loci. Brieger concluded that there are not enough mutable loci in maize to build up the necessary genic system with only recessive subviable mutations. He suggested that the dominance hypothesis should be rejected as an exclusive or general explanation of heterosis in maize. Brieger next studied the situa tion for heterotic mutants or genes which cause the heterozygotes to have a higher survival value than either the original normal genes
or the new subviable mutants. He compared the frequencies of heter ozygotes at equilibrium, (a) in a population in which 20 loci had mutated to heterotic allelic pairs, with average survival values of
RA. — 0.80, Ra = 0*60 and (b) in a population in which 200 loci had mutated at a rate of 10-^ to subviable recessives, with average
survival values of HA = 0.1, Ra = 0.75* Brieger found that it would
require about 200 loci which are capable of mutating to recessive
subviable alleles to be as efficient as 20 loci which had mutated to
heterotic subviable alleles. He concluded that the hypothesis of
heterotic gene interaction was in accord with the observed facts
and could be used to explain heterosis of any individual character.
Interaction between Alleles
East (39) in 1936 reviewed the evidence for each hypothesis
suggested for heterosis. As Shull (132) stated, East rejected the
dominant linked gene hypothesis and suggested a new hypothesis. 34
East’s reason for rejecting the dominant linked gene hypothesis was that normal and defective allelomorphs, such as A and a, could not, he thought, he effective in producing heterosis. East's explanation was that A is usually completely dominant to a, The effect of AA is not much greater than Aa. Thus he thought that heterosis must he interpreted through the behavior of normal allelomorphic series; also that the key to heterosis is the inheritance of quantitative characters. East’s hypothesis was based on several points. The first was that genes affecting quantitative characters rarely showed dominance. East’s second point was that frequency distributions from intraspecific crosses indicated that a simple additive interaction of multiple factors was inconceivable. Finally East thought that Rasmuscon (117) had explained the facts observed. Rasmusson assumes that the effect of a gene on the genotype depends on all of the other genes present, the effect of a certain gene being smaller the greater the number of genes acting in the same direction. East assumed a series of alleles at locus A, such as A^, A^ and Aj^, with the latter three each having a positive active function farther and farther from that of
A^. The combination of A-j_ A^ was supposed to have greater physiologi cal efficiency, provided the various functions were harmonious, than
A-^ East assumed there was no dominance. Richey (120, 121) maintained that with no dominance, A^ A^ would function less efficient
ly for the process controlled by the individual alleles than would
A]_ A-^ or A^ A^, although the final functioning of the heterozygote might be superior. Richey (120) stated that, to him, East's proposal
was the most understandable suggestion for a mechanism for the 35 blending inheritance of quantitative characters. However, he did not think it could explain heterosis, since he considered heterosis
different from quantitative inheritance. In some respects the con
ditions of and the results from an experiment conducted by Oliver and
Green (103) with Drosophila melanogaster are in harmony with East’s
hypothesis. Comparisons of the viability, fertility, and fucundity
were made for three recessive alleles of the lozenge locus, glossy
(lz&), spectacle (lsc), and lozenge (lz) in the homozygous and
heterozygous states. As a control the lz't (normal) was used. The
alleles for lozenge eye affect several characters. Each of the
alleles in the homozygous state were associated with significantly
lower viability, fertility, and fecundity than exhibited by the
controls. Heterozygous females were in general less vigorous in all
three tests than control females, but tended to show heterosis in
comparison with homozygous females. Oliver and Green concluded that
heterosis occurred as a result of the interaction of the recessive
lozenge alleles when heterozygous. The experiments conducted by
I>uckwill(88) with tomatoes have been discussed. In crosses between
varieties of closely related species, Luckwill was able to account
for only a part of the heterosis observed on the basis of Jones's
(72) hypothesis. Interspecific crosses in which one or both parents
were top dominants for all known size-determining genes exhibited a
large degree of heterosis. To explain these results with Jones’s
hypothesis would require the assumption that each parent lacked one
or more different and unknown growth genes. This appeared
improbable since two of the lines had been derived from wild species
for only a short time. Luckwill thought that East's hypothesis could be used to explain heterosis shown by the interspecific hybrids. It was assumed that the different species possessed homologous, though not identical, sets of genes in their chromosomes. There was some evidence for this assumption from L. esculentum and L . pimpine11- ifolium as their chromosomes paired at meiosis in the hybrid, but there were differences in the expression of characters in the two species. Luckwill accounted for the absence of heterosis, other than that brought about by the complementary action of dominant and recessive pairs, in the intraspecific hybrids, by assuming that within the species the genes concerned existed only in one isomeric condition. Sierk and VJinters (133) have discussed the means by which genes may act to bring about heterosis in swine. They studied data on 373 spring-farrowed litters containing 2,213 pigs of the
Minnesota number 1 and 2 lines, nine inbred Poland China lines, crosses of the inbred Poland China lines, and crosses representing different combinations of the three breeds. The Minnesota number
1 and 2 lines were considered as breeds in the last cross. More detailed information about the experiment is given in the section gn Measures used to Determine Heterosis in Other Classes of
Livestock. All of the lines were inbred, the average ranging from
22 to approximately 75 per cent. The Minnesota number 1 and 2 lines were based on crossbred foundations, but had been inbred. The vigor of the crossbred pigs was compared to the average of the
parental lines. Pigs from crosses of inbred Poland China lines
showed an average increase in vigor of 10.5 per cent, those from
crosses of inbred Poland China lines with the Minnesota number 1
and 2 lines showed increases of 18.2 and 12.ii per cent. Crossbreds 37 from the Minnesota number 1 and 2 lines showed an increase in vigor of 21,0 per cent over the average of their parents. Crosses of the
Minnesota number 1 and 2 lines and crosses of these lines with the inbred Poland China lines showed more heterosis than crosses of the
Poland China lines, Sierk and Winters thought these results indicated the importance of genetic diversity in relation to heterosis. They concluded that the genetic mechanism responsible for heterosis in swine was no more clearly defined than in plants. It was thought that some heterosis was due to the suppression of unfavorable re cessives, However, they pointed out that the relationship of genetic diversity to heterosis in their results favored East's (39) hypothesis. They explained that crossing of genetically diverse parents increases the chances of bringing together genes which complement each other, and which might never be paired in either parental line for the simple reason that both do not occur in either parental population.
Overdominance and Heterosis
Hull (6 7 ) in 19b% suggested that overdominance could be used to explain the extreme heterosis in corn. The term overdominance means that the heterozygote (Aa) is superior to either homozygote.
Lush (91) states that overdominance is a situation where the heterozygote has a selective advantage over both kinds of homozy gotes, According to Crow (30), when Shull and East were formulating the hypothesis of heterozygosity there was no direct evidence of any locus at which the heterozygote exceeded either homozygote* Because of the failure to find such loci, overdominance as an explanation 38 of heterosis was given up. Stadler (139) in 1939 pointed out that with soma of the R alleles in c o m a situation exists in which certain heterozygotes have more areas pigmented than either homozygote.
There are now more cases in the literature concerning single genes which are thought to show heterotic effects. Karper (77) in 1930 made one of the first reports on a heterozygots at one locus surpassing the
normal homozygote. A mutation for albinism had appeared in a pure
line of Kafir which had been inbred for seven years* The parent line was considered to be homozygous. Karper studied 380 plants of a
segregating progeny, of which 267 were shown to be heterozygous, 113
normal. While the differences in height during development and at
maturity were not great, the heterozygous plants were taller from
k0 days to maturity at 137 days. The heterozygous plants were
heavier at maturity and had heavier heads than the homozygous plants.
In 19Ul Stubbe and Pirschle (li+2) published a paper illustrating the
superiority of a monohybrid heterozygote. From strain 50 of
Antinhinum majus, they obtained a mutation called spectabilis. This
mutant was sublethal in the homozygous state and caused a partial
destruction of chlorophyll formation. The heterozygote was more
vigorous throughout than both homozygotes. Singleton (13U)
reported on a mutant semi-dwarf form, C30, which occurred in the
sweet corn inbred, Purdue 39. The mutant was normal and similar to
the parent in every respect except sizej it was smaller. Breeding
tests showed clearly that there was a one gene difference between
C30 and the parent P39• When C30 and P39 were each crossed to a
common inbred C13, the C30 x C13 cross yielded in some cases
significantly more than the P39 x C13 hybrids. The difference was 39 more pronounced when P39 and C30 were crossed with Cl5, also an inbred. Singleton concluded that a heterotic gene was involved, giving increased vigor in hybrids although the inbred itself was much reduced in size. Jones (7U) working with corn thought that he had obtained heterosis when inbred mutant lines which differed by one gene from their original parents were crossed with the original parents. However, Jones (75>) later found that the differences involved were not caused by single genes. After further work, Jones (76) came to the conclusion that other gene changes occur at or near the time
the visible mutants appear, or all heterozygosity of genes affecting
growth cannot be eliminated by continuous self-fertilization. Jones
pointed out that specific cases of single gene superiority or over
dominance are few, and even these may be due to multiple gene effects.
Gustafsson (62) has presented a series of data to show that mutations
lethal in the homozygous condition in plants actually may contribute
toward heterosis for viability, reproductive capacity, and other
characteristics when heterozygous. Gustafsson suggested that the
effect of two identical lethal genes might be to stop the normal
course of development. On the other hand, the effect of one lethal
gene in the heterozygous state might be to stimulate development.
He thought the idea that harmful mutations were a loss was wrong, and
that some of them were actually valuable tools in the dynamics of the
species. Two of the mutations Gustafsson described were albina 7 >
and xantha 3 3 chlorophyll mutations which had occurred in a pure line
of barley (Golden). The monohybrids or heterozygotes of these lethals
were, according to Gustafsson, superior to their normal sister plants
although the differences required large numbers in order to be i+0 definitely proved. These two mutations were combined (Gustafsson, 63) to form a dihybrid. They segregated independently of each other. The dihybrid showed heterosis when compared with the heterozygote for each lethal. The differences between the dihybrid and the original pure line were statistically significant. In this case the dihybrid, heterozygous for two lethals, was much superior to the lines contain ing only one lethal (monohybrids), from which it differed by one gene, and to the pure line parent from which it differed by two genes.
Quiriby and Karper (llU) have reported on heterosis in milo, which is the result of the heterozygous condition of a single gene that affects duration of growth. In this plant lateness is dominant to earliness except that recessive ma is epistatic to dominant Mag and Ma-^, and
Ma2 is epistatic to Ma^. The relationship of the genes results in eight homozygous genotypes but only four phenotypes for maturity:
Early, Intermediate, Late and Ultra-late. These phenotypes bloom
at 5>0, 70, 82, and 98 days respectively if planted in June at
Chillocothe, Texas, when the days are longer than lU hours. When the
plants are grown under 10-hour photoperiods, the four phenotypes are
identical for both size and duration of growth. These genes govern
the response of milo to photoperiod, also the time of floral
initiation. It should be noted that varieties of sorghum are naturally
inbred lines that are not changed by further Inbreeding. Quinby and
Karper thought that the various genotypes used as parents differed
only in the genes discussed here. In a cross between Dwarf yellow
milo (Intermediate, MaMa. Ma2 mag ma^ma^) x Sooner milo (Early, mama
ma.2ma2 ma3ma^) U7U plants in ten progeny rows were harvested and
grown into the generation. There were 120 Early, 118 Intermediate and 236 Intermediate-heterozygous (Mama Ma2mag ma^ma^) plants, almost a perfect fit for a 1:1:2 ratio expected from the segregation of a single allele. The Intermediate heterozygous genotype bloomed
13 days later than the homozygous Intermediate genotype, had 7 pe^ cent more stalks per plant, produced II4. per cent more heads and 19 per cent more stover. The differences were significant except for the number of stalks. Quinby and Karper concluded that the heterozygous condi
tion of the gene, Mama, in sorghum results in hybrid vigor comparable
to that in hybrid corn. Dobzhansky (33) has contributed to the
genetic analysis of heterosis through study of natural populations
of species of Drosophila. Populations of Drosophilia pseudoobscura
from different geographical regions differ in gene arrangement in
the third, the X, and, less frequently, in other chromosomes. The
differences in gene orders is due to inversion of chromosome sections.
The chromosomal types interbreed at random; hence, inversion
heterozygotes and homozygotes are found in nature. From previous
work, Dobzhansky had formulated the hypothesis that natural selection
may have produced polygene complexes in different populations that
differed, coadapted within but not between the populations. If this
is correct, inversion heterozygotes which carry two chromosomes from
different populations may not show as much heterosis as is observed
within these populations themselves. Dobzhansky thought the hypothesis
had withstood the test. Dobzhansky compared inversion heterozygotes
with two third chromosomes of different geographic origin to inversion
homozygotes with two third chromosomes of the same origin, and the
heterozygotes failed to show heterosis for viability. Inversion
homozygotes carrying third chromosomes of different geographic origin U2 were compared with inversion heterozygotes carrying third chromosomes
of similar geographic origin* The heterozygotes were superior to the
two homozygotes (AR/AR) (ST/ST) in viability* According to Dobzhansky,
inversion heterozygotes in D. pseudoobscura, which carry two chromo
somes derived from the same population usually show heterosis, whereas
heterozygotes which carry chromosomes from geographically remote popu
lations usually do not* Dobzhansky (3h) thought the results compatible
with the assumption that the overdominance in fitness observed in the
heterozygotes is the property not of a single gene locus or of a
chromosome structure but of integrated systems of polygenesj also that
polygenic systems are coadapted by natural selection to other polygene
complexes present in the same population* The importance of the
chromosomal inversions in heterosis in balanced polymorphism lies in
the suppression of crossing over caused by most inversions, at least
in Drosophila* Buszati-Traverso (11) has published some results on the
selective advantage of heterozygotes in Drosophilia melanogaster. He
observed in two different wild stocks an eye color which was lighter
than normal* The two mutants proved to be recessive alleles at the
same locus in the third chromosome. Later wild flies were collected
which carried the same gene. Finding the same gene in laboratory
stocks and in the wild indicated that it had a positive selective
value. In an experiment where the gene frequency to start with was 0*5
each for light-eyed and the wild type, the frequency for the light-eyed
gene was 0.63 after twenty generations. This proved that the gene had
a positive selective value. In another experiment, two groups of flies
had a gene frequency of the light-eyed mutant of 0.125* Two had a gene
frequency of 0*5* and two had a gene frequency of 0*875* After fifteen generations, the three experimental populations, each in duplicate, had reached the same gene frequency at ahout 0.579*
Buzzati-Traverso concluded that natural selection had been acting on the three populations to produce the same results, regardless of the initial gene frequency, and that selection had been in favor of the heterozygous flies. The homozygous mutant was slightly superior in survival value to the homozygous normal allele. Hull’s (6 7) original argument for overdominance was based on the fact that in most cases, the hybrid from crossing two inbred lines of c o m has a greater yield than the sum of the two inbreds. According to Crow (30) this would not be possible with dominant genes acting in a completely additive manner unless it were assumed that a plant with no favorable
dominants had a negative yieldj also that the validity of Hull’s argument depends on the unimportance of eipistasis in corn yields.
The evidence on this point is incomplete and contradictory. Hull (6 9 )
has suggested three conditions under which overdominance may occur.
First, when aa is neutral and Aa nearer to an optimum dose of A than
is AA; second, when A.-** and A are both active for separate supplementary
functions and each is dominant to the other for its own function; and
third, when A-*- and A are both active for separate primary functions,
and the primary functions interact to produce an effect greater than
those of either A~*~A'*' or AA. Hull points out that the frequency of
heterozygotes is greater and of homozygotes less for any locus with
multiple alleles present in a crossbreeding population. Therefore if
heterozygosity is of general advantage, multiple alleles should
provide more heterosis. Hull. (68, 6 9 ) attempted to prove that over
dominance exists by calculating the regression of yield of the F-j_ o n ill; yield of the Inbred parents* The analyses Indicate a zone of nearly level regression near the upper end of the data, where, he stated, it might be predicted taking into account the kind of artificial selection that has been practiced and if overdominance exists* Crow (30) stated that overdominance is not the only possible explanation of such results* In addition, any technique making use of yield data on in- bred lines is complicated by the lack of consistent results with inbreds* It is also possible that the genes responsible for yield in inbreds are largely different genes from those determining yield in the hybrids. Crow stated that it is not possible to be sure of the importance of overdominance from Hull*s methods, but they at least suggest overdominance. According to Lush (91) the importance of overdominance and how frequently it occurs is not clear* Only a few cases are as yet known clearly from the I-fondelian viewpoint, one of them being roan color in Shorthorn cattle* Other specific cases where overdominance seems to be shown are those reported by Gustafsson (62) and Gowen et al* (60), but they have not been completely analyzed*
Lush thought that overdominance was a plausible explanation for heterosis and that East (39) was referring to it in vague terms.
A review of the literature dealing with genetic explanations of heterosis brings out the fact that at present there is no one explana tion of the phenomena. Whaley (l£l) pointed out that heterosis is to be explained genetically in terms of various recombination effects*
Dominance may be the important consideration, or it may be heterozygosity. One or many genes may be involved. Hayes (61i) considered heterosis to be the normal expression of a complex character when the genes concerned are in a highly heterozygous condition* Crow (30) stated that with the number of genes involved there must be all sorts of complex interactions in heterosis* For this reason no single hypothesis can be expected to account for the entire effects of heterosis. Sprague (138) pointed out that while diverse types and degrees of gene interaction may occur in an organism, there are some data indicating that for a given organism, interaction may be predominantly of one type* Crow (30) agrees that the various hypotheses may not be equally important in all situations* Mather
(99) discussed the dominance of linked genes and heterozygosity hypotheses* He stated that the recent trend toward the idea of genetic diversity and the idea that heterozygotes are more stable in develop ment, come very close to the heterozygosity hypothesis as an explana tion of heterosis* Mather gave two arguments against this, the first being that heterosis is a regular property of hybrids only in naturally outbreeding species. Hybrids from inbreeding species do not always exceed the homozygous parents in vigor or stability of development.
Mather stated that in inbreeding species, heterozygosity is not of itself sufficient, and either the heterozygosity hypothesis must be abandoned or one hyp°'thesis accepted for outbreeding species and another for inbreeding species. The second objection is that if mere heterozygosity has a stimulating effect, the phenotype of the hetero- zygote should be better than the phenotypes of corresponding homozygotes. The genes should show not only dominance but over dominance* Mather stated that overdominance has often been claimed and seldom, if ever, proved in relation to heterosis, because it is not easy to distinguish from interaction between non-allelic genes* us
Measures Used to Detemine Heterosis in Dairy Cattle
In reviewing the literature on crossbreeding in dairy cattle, and the measures used to determine heterosis, emphasis has been placed on those studies which were concerned with milk and butte rf at yields, energy yield expressed as ^ per cent fat-corrected milk, persistency of production, length of gestation, weight at birth, growth rates, size at maturity, and body type.
The literature on the crossing of Indian cattle and cattle of the recognized dairy breeds has not been reviewed, since crosses with
Indian cattle are not involved in this study*
In discussing crosses between two breeds, the breed of the bull is always given first and the breed of the cow second.
Milk Yield
Kirchner (80) published in 1910 one of the first articles on the crossbreeding of dairy cattle. The crossing was done in order to determine the inheritance of buttarfat percentage. A Guernsey luil was crossed with one cow each of the East Friesian, Breitenburger and
Pinzgauer breeds. Kirchner also crossed an Angler bull with the
Pinzgauer cow. Some of the lactations were affected by hoof and mouth disease and tuberculosis. The Guernsey x East Friesian crossbred produced 3,186 kg. of milk in 292 days in her fourth lactation, while her East Friesian dam produced 5,2lU kg. of milk in 366 days in her fourth lactation. An East Friesian maternal sister to the crossbred produced 2,883 kg. of milk in 275 days in her second lactation; however, this lactation was affected by hoof and mouth disease. The only Guernsey available for comparison produced 1,961 kg. in 300 days • 1+7
The Guernsey x Breitenburger crossbred produced 2,815 kg. of milk in 315 days in her third lactation, compared with her dam’s third lactation production of 3*151+ kg© of milk in 315 days. The
Guernsey x Pinzgauer crossbred had hoof and mouth disease in her first two lactations, so was sold with no comparison being obtained. The
Angler x Pinzgauer crossbred produced 2,2lil kg. of milk in 239 days
in her first lactation. Her dam in her fifth lactation produced
l+,032 kg. in 29k days. Three Angler females were used for comparison with the crossbred; however, one did not have a normal record. The
other two cows produced 2,211 kg. in 291 days in the second lactation,
and 3*292 kg. in 365 days in the third lactation respectively.
Parlour (107) in 1913 reported that a herd of Aberdeen-Angus x
Jersey crossbreds was being developed in the northern part of
England. Since the owner had found the climate too severe for Jerseys,
he bred his Jersey females to an Angus bull. The F-^ animals were then
mated to obtain an Fg generation. Males and females from each
generation were to be mated to produce the next generation. All of
the F^_ females except one were equal to their dams for milk production.
KuhZLman (81) reported that the F^ Aberdeen-Angus x Jersey cows in the
herd mentioned above produced almost as much milk as their Jersey
dams. The level of production was about i+,000 pounds of milk.
Gowen (53* 51+) first reported in 1918 results of the crossbreed
ing experiment at the Maine Station. This experiment was started
by Dr. Raymond Pearl in 1913* the objective being to study the
inheritance of milk yield, butterfat percentage, and other characters.
The breeds chosen for making the first crosses were Jersey Holstein- hs
Friesian, and Aberdeen-Angus. Later crosses involving Ayrshires and
Guernseys were made. Reciprocal crosses were made for the following two-breed combinations: Jersey x Holstein, Aberdeen-Angus x Jersey,
Aberdeen-Angus x Guernsey, and Aberdeen-Angus x Holstein. Crosses were also made in the following combinations, the breed of the bull in the cross being listed first: Holstein x Guernsey, Aberdeen-Angus x Ayrshire, and Holstein x Ayrshire. Animals of the F-^ generation were used to produce the generation. Environmental conditions for all animals were as uniform as it was possible to make them. The amount of inbreeding which had taken place to produce each foundation animal was determined. In general it was low, and it was concluded that the
inbreeding would have little effect in increasing the vigor or milk
production of the crossbred animals.
Gowen (5£) presented an analysis of the milk production of the
parents and their crossbred progeny. The records were standardized
for age by calculating to a two-year-old basis each month's
production for the first eight months of a lactation. The correction
factors used were the mean of those developed at the Maine Station for
the Guernsey, Holstein, and Jersey breeds. If a cow had more than
one record, the corrected production for the corresponding months of
each lactation was averaged. The record for a single lactation was
a total of the production for the eight months. When there were two
or more records, the average productions for each of the eight months
were added together. The single record based on one or more lacta
tions converted to a two-year-old basis was used as a measure of the
cow's milk production. The same set of conversion factors was used
for the records of all cows in the experiment. h9
The potential transmitting ability of each bull was estimated*
For two bulls, one Holstein and one Jersey, the mean of all purebred daughters was used after the milk records had been put on the same basis as those of the crossbreds and their purebred dams* One
Holstein bull had no purebred daughters with records, so the average of the daughters of the Holstein bull mentioned above was used as his transmitting ability* The Angus bull had no purebred daughters in production, so his transmitting ability was estimated as the average of the corrected two-year-old records of the Angus cows in the herd.
Gowen analyzed the data by expressing the number of times an animal resembled one parent more closely than the other parent*
Crossbred no* 1 resembled her low producing parent for milk 7*7 times as closely as her high producing parent* The other eleven animals resembled the high producing parent for milk production from 1*5 to
18*0 times as closely as they did the low producing parent, with an average of lj.*76. Gowen concluded that these results indicated that milk production was transmitted through genes which were partially dominant* Because of crossbred number 1, Gowen did not think that heterosis was the cause of the eleven animals being closer to the higher producing parent* He suggested that no* 1 was a segregate of low milking genes from high milking genes carried by her dam* Two of the crossbreds were better than either parent, whereas the remaining ten were better than the lower parent but not better than the higher
parent•
Castle (17) in 1919 published the first report on the herd which
has become known as the "Bowlker herd.11 This herd was established in
1911 "by Mr* T. J. Bowlker whose farm was at Framingham, Massachusetts. 50
Mr. Bowlker undertook an experimental study of the inheritance of milk yield and butterfat percentage by making reciprocal crosses of purebred
Guernsey and Holstein cattle. He thought that if milk yield and butter- fat percentage were inherited independently, it should be possible to combine them in a single breed. Animals of the F-^ generation were mated to produce an F^ generation. The environmental conditions were the same for the purebred and crossbred animals, the feeding and care being comparable to that being given ordinary herds at that time.
The cows were milked twice a day and each milking was weighed.
Butterfat tests were not made regularly, thus making the data less valuable. Mr. Bowlker died in 1917 and ±n 1919 the herd was acquired by the University of Illinois.
Castle reported on the results obtained before the herd was
shipped to Illinois. He used actual first and second lactation milk
records up to 365 days in length. No adjustments were made for age or length of lactation. Data were given for first lactations on 21; purebred Holsteins, 8 purebred Guernseys and 31 first generation
crossbreds. The Holsteins averaged 7,673 pounds of milk, the Guernseys l;,6l7, and the crossbreds 6,612 pounds of milk. The average ages of
the groups were approximately the same:; however, the Guernseys milked
an average of one month less than the two other groups. Castle
compared the average of the crossbreds with the mean of the two
parent breeds, the crossbreds exceeding the parents by h67 pounds of
milk. In comparing second lactation records, the crossbreds exceeded
the mean of the two parent breeds by 1,129 pounds of milk. No
consistent difference was noted between animals of the reciprocal
crosses, and it was concluded that sex-linked factors were not 51 involved. Castle interpreted the results as comparable to those obtained in studies of the inheritance of size, and other quantitative characters both in animals and plants* He stated that the F-^ usually- surpassed more or less the intermediate between the races crossed, because of the superior vigor possessed by crossbred organisms.
Yapp (162) reported on the production records made in the
University of Illinois herd by the F^_ and F^ generation Bowlker cows.
These records were made in the first lactation, and were US weeks in
length. All of the cows freshened at approximately the same age.
Forty-seven F-^ generation females averaged 7,2U6 pounds of milk,
whereas 38 Fg daughters of the F^ females averaged 6,883 pounds of milk. The difference in production in favor of the F-^ coxtfs was
accounted for by their greater persistency from the 30th to the
U5th week. Robertson (12U) has called attention to the fact that the
figures given by Yapp are higher than Castle’s. He suggested that
the management of the herd at the University of Illinois was better
than at the Bowlker farm.
Ellinger (1±2, U3) reported in 1923 on a large crossbreeding
experiment started in 1906 by Count F. Ahlefeldt Laurvigen, Tranekjaer
Castle, on Lange land in Denmark. This has become knoxcn as the
"Tranekjaer" herd. Jersey bulls were mated with Red Danish cows to
produce crossbreds, which x-/ere then bred to Jersey and Red Danish
bulls to produce backcross animals. An Fg generation and second
generation backcrosses to the Jersey breed Xirere also produced.
Purebred daughters of the Jersey bulls used to sire the crossbreds
were also obtained. The cattle in this herd were managed and fed
uniformly on a strictly commercial basis. Eaeh animal was tested 52 regularly throughout its life for milk yield and butterfat percentage*
Ellinger (U2) analyzed the data by using first lactation records made by cows twenty-eight to thirty-five months of age at freshening, with no correction being made for age. All records were corrected to
a March basis because Ellinger found that cows freshening in October
produced 16 per cent less milk than cows freshening in March. The milk record used for comparison was the production for 70 days,
beginning with the second week and continuing through the eleventh
week. No specific daughter-darn comparisons or comparisons of cross
breds and their purebred sisters were made. The data were given as
averages for the different groups classified according to inheritance.
The average milk yield (1;2, 1+3) for 260 Red Danish cows was 896 kg .5
their 75 crossbred daughters, 832 kg.; and for the ll+O purebred
daughters of the Jersey sires, 712 kg. The three-fourths Red Danish
cows averaged 88l kg.; the three-fourths Jersey cows 7U2 kg.; and
the seven-eights Jersey cows averaged 700 kg., of milk. Ellinger
concluded that the crossbreds were intermediate between the two
parental breeds, and the backcrosses were intermediate between the
crossbreds and the parental breed used to make the backcross. He
concluded that the results were typical of those obtained in
experiments with multiple factors.
A crossbreeding experiment was conducted at the University of
Wisconsin from 1912 to 1933. Cole reported preliminary results from
this experiment in 1923 (23) and 1921+ (21+) in identical papers. This
experiment was started in order to study the inheritance of various
characters in cattle. Cole and Johansson (25) stated that the
objective was to study the inheritance of such economically important 53 characters as rate of growth, beef qualities, milk yield, and butter fat percentage. The breeds chosen at the beginning were the Aberdeen-
Angus and Jersey, Later (21;) the Holstein breed was substituted for the Jersey, because the Holstein showed a greater difference in size, milk yield, and butterfat percentage when compared with the Aberdeen-
Angus breed. Reciprocal crosses were made with the Aberdeen-Angus and Jersey, and Aberdeen-Angus and Holstein breeds. An Fg generation was produced from the F-j_ generation of both crosses. After the death of Dr, Cole in February, 19^+8, three papers which deal with many of the aspects of this experiment were published in Volume 82 of the
American Naturalist, They had been written by Dr. Cole and Dr,
Ivar Johansson.
The environmental conditions in the YJisconsin experiment (25) were kept as uniform as possible throughout its duration. The cows were barn fed except when dry. The aim was to maintain feeding and management conditions comparable to those on good farms. All F-^ and
F 2 females were kept in the herd until they had completed at least two lactations. The experiment was terminated in 1933 and all animals were slaughtered at that time. As Cole and Johannson analyzed the milk production data on a fat-corrected milk basis it will be discussed later*
White (153) described the breeding plan followed by the United
States Department of Agriculture in an effort to produce a hardier
dairy cox* for Alaska by crossbreeding* The breeds used xrere the
Galloway and Holstein, the experiment being started by mating purebred
Holstein bulls with Galloxvay cows. Later reciprocal matings were made,
also a few backcross matings. Each generation of crossbreds was 5U interbred to produce the next crossbred generation. The experiment was started in 1917 and continued until 1932 when it was turned over to the Alaska Agricultural College. In 1932 one calf of the generation was in the herd.
A complete analysis of the milk production data from this herd was not published. White and Ibsen (l5U) stated that considerable progress had been made in developing a dairy cow for Alaskan conditions.
The foundation cows were not high class animals* the Holsteins producing from 5,000 to 8,000 pounds of milk, and the Galloways even less. Georgeson (5l) stated that the experiment was started at Kodiak,
Alaska, but because of the difficulty of importing concentrates the herd was moved to the Matanuska station in 1925• The crossbreds made records from Lj.,000 to 6,000 pounds of milk at Kodiak. Alberts (1) and White (152) reported on the production of eleven crossbred and five Holstein cows that completed lactation records in the herd during
1930 and 1931. The relationship of these cows was not given but it can be assumed that they were related to some extent. All of the
Holstein records were above 7,000 pounds of milk, with two cows producing 12,371 and 13,7U8 pounds of milk. The crossbreds were more variable than the Holsteins, one producing as low as 3,776 pounds of milk in a short lactation, and others producing below 7*000 pounds of milk. Three crossbreds made records of 10,553* 13*169* and 13*2U7
pounds of milk. Alberts stated that when age was considered, the
crossbreds were consistently better milk producers than the Holsteins.
Gasser (50) reported that all of the crossbred cows that had completed
lactation records averaged 7*510 pounds of milk. Ten of the cows
produced over 10,000 pounds of milk in a lactation, one cow producing lit.,599 pounds in 365 days. According to Gasser some of the crossbreds were "worthless" as dairy cows. The results indicated possibilities, but it was thought it would take too long to develop the herd to the point where good dairy animals could be produced with reasonable certainty. Consequently, the experiment was terminated and the animals sold for beef in 1935*
An experiment in crossing animals of the Holstein and Jersey breeds was carried out at the South Dakota Station from 1925 to 1936.
Wilson (156) stated that the objective of the experiment was to find out if milk yield and butterfat percentage were inherited separately.
In addition the influence of crossbreeding, linebreeding and inbreed ing on conformation, hardiness and fertility were to be studied.
Apparently, this experiment never developed according to the original p l a n s ♦
Olson (lOlj., 105 * 106) made short reports on the South Dakota
experiment. Reciprocal crosses between the Holstein and Jersey breeds were made. At least nine cows (106) completed lactation
records^ however, data were reported on only three crossbreds and
their dams (105)• A Holstein x Jersey crossbred produced 7*691
pounds of milk in twelve months compared with 3,709 pounds produced
in nine months by her Jersey dam. Two Jersey x Holstein crossbreds
produced li, 6 2 6 and 1 1 , 7 2 0 pounds of milk in ten and twelve months,
compared with 9*585 and 8,170 pounds of milk produced by their
respective Holstein dams in twelve months. Olson concluded that
the increased production of two of the daughters over their dams
was not due to crossbreeding but to their sires. The sires were
proved, but no data were given on their proofs. 56
Prentice (113) gave a short account of the breeding of dairy cattle at Mt, Hope Farm, Williamst.own, Massachusetts, Crossbreeding was practiced at Mt, Hope, but no complete summary has ever been published on the results obtained. The cattle at Mt, Hope were originally Guernseys, The foundation cows, 15 in number, averaged
8,366 pounds of milk on a twice-a-day milking, 305 day lactation, mature equivalent basis. Seventy-four purebred daughters of these cows averaged 9,161 pounds of milk on the same basis. In 1926 the crossbreeding was started by purchasing cows of other breeds and breeding them to Guernsey bulls. In 1937 one Jersey and two Holstein bulls, proved as sires of high production, were purchased. They were used in the herd in addition to Guernsey bulls and in 1939, 191+0 and
19i|l the herd averaged 13,398 pounds of milk. These records were made in a dairy herd improvement association and were on a twice-a-day milking, 305 day lactation, mature equivalent basis. The data that are available on the Mt. Hope herd are not sufficient to arrive at
any conclusions.
Byckov (12) reported on the results obtained from crossing East
Friesians and Ayrshires on a state farm in the Kunstev district of the
Moscow Province. Between 19U6 and 19^9 an Ayrshire bull was bred to
Ii0 East Friesian cows. At the same time, 20 Ayrshire cows were bred
to East Friesian bulls. In 300 day lactations the crossbreds by the
Ayrshire bull from East Friesian cows averaged U,176 kg. of milk.
In the same length of lactation, a group of East Friesian cows
averaged U,ll(.2 kg, and a group of Ayrshire cows averaged 3,673 kg.
of milk. No information was given concerning the relation of the
Ayrshires and East Friesians to the crossbreds. No data were given, 57 but it was stated that the crossbreds by East Friesian bulls from
Ayrshire cows produced less milk than the reciprocal crosses discussed
above.
The crossbreeding experiments cited up to this point were started
either to obtain information on the inheritance of various characters
in dairy cattle or to develop a new breed which would produce large
amounts of high testing milk. None of them were specifically designed
to find out whether or not heterosis could be demonstrated when dairy
cattle of two different breeds were crossed. In recent years results
from four dairy cattle breeding experiments have added to our knowledge
of heterosis.
In 1939 Fohrman et al. (I4.6 ) started a crossbreeding experiment
at the Agricultural Research Center, Beltsvilie, Maryland. Four dairy
breeds, Holsteins, Jerseys, Guernseys, and Red Danes were used in
making the crosses. The foundation females of the Holstein, Jersey,
and Guernsey breeds were brought to Beltsville from the United States
Department of Agriculture field station herds. These females were
from herds in which a series of proved sires had been used. Some of
the records of the dams were made at the field stations and others
were made at Beltsville. All of the Red Dane females were in the herd
maintained by the Department of Agriculture at Beltsville. All bulls
used to sire the two-breed crossbred calves were proved. The Holstein
bull was proved in a cooperatorTs herd on 31 daughter-darn comparisons.
The daughters averaged l8 ,lfL6 pounds of milk and 6U5 pounds of butter
fat as compared with 1 7 * 7 7 2 pounds of milk and 61 9 pounds of butterfat
for their dams. These records were on a three times-a-day milking,
305 day lactation, mature equivalent basis. The Jersey and Red Dane 58 sires were proved in the purebred herds at Beltsville*
The plan of the experiment differed from those of previous cross breeding experiments. For example, a Jersey cow was mated to a Holstein bull, and the resulting two-breed female was then mated to a Hed Dane bull to produce a three-breed female. The three-breed female was mated to either a Jersey or Holstein bull. If a Jersey bull was used, then
Holstein and Red Dane bulls were vised to sire succeeding generations.
Ey this plan new genes were introduced with each new generation. In addition, these new genes were from bulls that had demonstrated their ability to sire high producing daughters. In the beginning, reciprocal crosses were made in all possible combinations except with the Guernsey breed. Reciprocal crosses with the Guernsey breed were not made because a proved Guernsey bull was not available. Three-breed females
that had Guernsey inheritance were mated to bulls of a fourth breed
to produce four-breed animals. A limited amount of intemating of
the crossbreds was done in order to check on the transmitting ability
of some crossbred bulls.
All of the females were raised, weighed, and measured periodi
cally. The producing ability was determined in the first lactation
under uniform environmental conditions. The cows were milked three
times a day for 365 day lactations, and bred four and one-half months
after calving. The dams had also made their records on three times-
a-day milking for 365 day lactations. The cows were barn fed during
the first lactation.
Fohrman et al. (1*6) reported that 55 foundation cows averaged
13,799 pounds of milk, 55 two-breed daughters averaged 1 7 , 8 1 1 pounds,
5 8 three-breed crosses averaged 1 8 ,21*0 pounds, and 23 progeny of 59 three-breed cows averaged 1 7 ,761; pounds of milk on a 3x, 365 days mature equivalent basis* The standard deviations and coefficients of variation were highest for the foundation cows, lowest for the two- breed cows, and slightly higher for the three-breed cows. The coefficients of variation were 3512.9 , and 1 7 * 5 respectively.
Only one of the proved sires failed to transmit according to his daughter-dam comparison on purebred daughters. The conclusion was that when proved sires are used in a three- or four-breed rotation, a large increase in milk can be expected in the first cross, with slight increases in subsequent crosses.
Fohrman (U5) reported that five crossbred bulls were bred to a limited number of crossbred females. Daughters of two of the bulls had completed records. Two daughters of a Red Dane x Holstein bull averaged ll;,783 pounds of milk in their first lactations. A three- breed bull sired by a Red Dane bull, and from a Jersey x Holstein cow, had a daughter that produced 13,2l;l pounds of milk in her first lactation.
Schmidt (126) described a crossbreeding experiment begun in 19l;0 at the Kaiser Wilhelm Institute for Animal Ereeding Research Dummer-
storf, Germany. Black and white Lowland cows, which Robertson (121;)
called Friesians, and Jersey bulls were used in making the crosses.
In addition to making crosses at Dummerstorf herdbook cows in the
Rostock area were inseminated with semen from the Jersey bulls. The
female calves were purchased by the Institute, where at the time of
this report there were 85 F^ females and seven F-j_ bulls. The
Friesian cows used in this experiment were medium producers and their
milk was low in butterfat content. The reason for this was that as 60 much difference as possible was wanted between the butterfat tests of the breeds used, so that the inheritance of butterfat per cent in the crossbreds would be clear cut*
The F^ heifers were to be bred to an bull and a Dutch bull.
In addition, Red Pied Lowland cows were crossed with Jersey and Red
Danish bulls. Several other breeds were being crossed with each other.
The object of this crossing program was to raise butterfat production of the German cattle. There was no indication that Schmidt was trying to deteimine whether heterosis resulted from the crosses he made.
Schmidt (127) reported on the results obtained by crossing
Friesian cows with Jersey bulls. Twelve crossbreds produced an average of 3*258 kg. of milk in the first lactation, and the Friesian dams produced an average of 3 ,1*52 kg. of milk in their first lacta tion. The length of lactation was 305 days. The highest production for a crossbred was 3 * 7 2 0 kg. and the lowest production 2 ,939 kg. of milk. The highest and lowest dams produced U*980 and 1,983 kg. of milk respectively. The Jerseys used for comparison were 19 unrelated cows that made their records under the same conditions as the cross breds. They averaged 2,355 kg. of milk. However, these cows were in
the process of becoming acclimated, and Schmidt thought their records were too low. The Jersey dams of the four bulls used averaged 3*313 kg. but Schmidt thought this average could not be used for comparison because each dam had made several records. Schmidt compared the
production of the crossbreds, their Friesian dams, the 19 Jersey cows,
and the dams of the Jersey bulls on the basis of milk produced per
100 kg. of body weight. The crossbreds produced 721; kg. of milk per
100 kg. of body weight compared with 690 kg. for their Friesian dams. 61
The 19 Jersey cows produced 628 kg.; and the dams of the Jersey bulls,
883 kg. of milk per 100 kg. of body weight.
Smith (135) reported on the crossbreeding work at the University
of Edinburgh. Crosses were made between different breeds, but
apparently no effort was made to obtain large numbers of reciprocal
crosses. The crosses made were Ayrshire x Shorthorn, Ayrshire x
Guernsey, Jersey x Ayrshire (crossed both ways to obtain reciprocal
crosses), Red Polled x Ayrshire and Red Polled x Shorthorn. The
Ayrshire x Guernsey crosses were intermediate in milk production
between the two parent breeds. The Jersey x Ayrshire cross x^hieh was
made both ways produced animals which were intermediate, with some
exceptions, to the parent breeds.
Smith stated that in no case did an animal exceed both parents
with a high yield of milk of high butterfat content. Sackcrosses
were made to each of these breeds and the resulting progeny were in
most cases below the breed to which the baclcci’oss was made. The Red
Polled x Ayrshire cross produced animals which were poor producers,
and the Red Polled x Shorthorn cross was not successful. Smith
stated that there was no evidence of heterosis in the crossbreds,
and he thought nothing had been achieved which could not be done
better by selecting within the breed.
Smith found that the Ayrshire x Shorthorn crossbreds and back-
cross animals were better producers. Some of them were low producers
but several pi-oduced over 10,000 pounds of milk in 305 days. Nine
cows, sired by one Ayrshire bull, averaged 9,^00 pounds of milk in
305 day lactations on three times-a-day milking. The records were
not corrected for age before the average xoas obtained. The purebred 62 daughters of this sire, in the same herd, had a higher average production by about 1 , 0 0 0 pounds of milk in 305 day lactations.
Woodward and Graves (160) compared inbred and outbred daughters
of seven inbred grade Holstein cows to see whether heterosis had been
shown. They also compared a group of daughters of inbred grade cows
that were sired by unrelated bulls with registered daughters of these
bulls in the Beltsville Holstein herd. The inbred cows were in an
inbreeding experiment being conducted at the Agricultural Research
Center, Beltsville, Maryland. The experiment was started by breeding
a Holstein bull to lh grade cows representing various breeds. This
sire was then bred to his daughters and succeeding generations of
female descendants as long as he lived. Seven other bulls inbred to
the original bull were used in the experiment.
First records, 365 days in length on three times-a-day milking
were used to evaluate a cow’s producing ability. Most of the heifers
calved between the ages of two and two and one-half years, the average
age being two years, two months and ten days. The records of those
heifers that did not calve between two and two and one-half years were
adjusted to the average age. Except for these adjustments, the actual
production was used for comparisons. Seven of the inbred cows had
1 1 inbred daughters (coefficient of inbreeding, U2 .5 ) that produced
an average of 11,231 pounds of milk. These inbred cows had seven
daughters by unrelated registered sires that averaged 1 2 ,1)56 pounds
of milk, or 1 ,225 pounds more than their inbred maternal sisters.
Only two inbred heifers were better in milk than their respective
outbred sisters.
Another comparison was made between two groups of daughters of & ‘ 63 four bulls, one group of 12 being from inbred dams and the other group of 12 being from registered cows in the Beltsville herd. The weighted average production of the daughters from the registered cows was 13,377 pounds of milk compared xcLth an average of 12,669 pounds
for the 12 daughters of the inbred cows. Three of the bulls had
only four daughters from the inbred grade cows, the fourth bull having
eight daughters. The daughters of this bull averaged 12,152 pounds of
milk compared with 12,387 pounds for their dams. This bull had six
inbred daughters from registered cows that averaged 12,752 pounds of
milk compared with 12,158 pounds of milk for their dams. This was an
increase of $9h pounds of milk.
Butterfat Yield
Kirchner (80) reported that a Guernsey x East Friesian crossbred
produced 117 kg. of butterfat in 292 days in her fourth lactation,
compared with 126 kg. produced by her dam in 3 6 6 days in her fourth
lactation. An East Friesian daughter of this dam produced 82 kg. in
275 days in her second lactation, which was affected by hoof and mouth
disease. A Guernsey used for comparison produced 86 kg. in 300 days
in her first lactation. The Guernsey x Breitenburgher crossbred in
Kirchner's experiment produced 120 kg. of butterfat in 315 days in
the third lactation, whereas the dam produced 115 kg. of butterfat
in 315 days in the third lactation. The Angler x Pinzgauer crossbred
produced 85 kg. of butterfat in 239 days in the first lactation,
compared with 166 kg. produced by her dam in 2 9 i+ days in the fifth
lactation. Two Angler females used for comparison produced J2 kg.
in 2 9 1 days in the second lactation, and 113 kg. in 365 days in the 6U third lactation respectively.
Gowen*s (55) analysis of the results obtained for milk production in the Maine crossbreeding experiment has been discussed under milk yield. Later (56) Gowen presented the butterfat percentages for the different crossbreds, their dams and the transmitting abilities of their sires, either actual or estimated. The butterfat percentage for a female was obtained in the same manner as the milk production record which has been described, except that two sets of factors were used to correct the records to a two-year-old basis, one for Ayrshires and another for the other groups. The actual or estimated transmitting ability of each of the bulls was obtained as previously described.
Gowen did not analyse the data on the basis of butterfat yield. The milk records and butterfat percentages as given by Gowen (553 56) have been used to calculate butterfat yield for the eight months' lactation. The level of butterfat production was low, only one of the 12 crossbreds produced above 200 pounds. The dams were all below
200 pounds of butterfat, and the two Aberdeen-Angus dams were below
75 pounds. The transmitting ability of each sire, either actual or estimated, was below 200 pounds butterfat and that of the Angus bull
73 pounds. Eight of the crossbreds were intermediate between the
high and low parents, but better than the average of the two parents
for buttterfat production. Two were above both parents and two below both parents. The two below both parents were sired by a Jersey bull
and from Holstein cows. The Holstein dam was the lowest parent in
each case and the crossbred daughter was only a few pounds below the
dam in each instance. One of the animals above both parents was sired
by a Holstein bull and from a Guernsey cow, and she was the highest crossbred with 208 pounds of butterfat. The other crossbred better than both parents was sired by the Aberdeen-Angus bull and from an
Ayrshire cow. The daughter produced l$h pounds of butterfat and the dam lUl pounds. .Seven of the eight crossbreds between their parents for butterfat production were either sired by an Aberdeen-Angus bull or from an Aberdeen-Angus cow. The eighth crossbred between her parents was sired by a Holstein bull and from a Guernsey cow.
Although the records given for this experiment cover only the first eight months of production, they are very low. The environmental conditions were uniform, but they must have been at a low level or the animals used in this experiment must have had poor inheritance
for milk and butterfat production.
Castle (17) reported on the butterfat production of animals in the Bowlker herd. Butterfat percentages were available on only
8 of 2i|. Holstein cows, the average being 3*U per cent. As this was
close to the breed average found by Roberts, it was assumed that the
rest of the cows averaged per cent. The purebred Guernsey cows
that had been tested averaged S »0 per cent, and this figure was used
for the Guernseys. The crossbred cows had all been tested several
times, so the tests for a cow were averaged to obtain her butterfat
percentage. Castle found that 2)4 Holstein cows averaged 26l pounds
of butterfat at two and eight-tenths years of age in 11 months.
Eight Guernsey cows averaged 231 pounds of butterfat at two and
seven-tenths years in ten months. Thirty-one crossbreds averaged 270
pounds of butterfat at two and six-tenths years in 11.1 months. When
second lactation records were compared, 20 Holstein cows averaged 322
pounds, 8 Guernseys 280 pounds, and 13 crossbreds 363 pounds of 66 butterfat. Castle's data are open to criticism, in that the butterfat percentages probably were not accurate. The assumption of certain butterfat percentages for the two parent breeds may have introduced
errors, although the average per cent butterfat for the eight Holstein
cows with butterfat tests was close to that used for the whole group.
The method of analysis was faulty in that no specific daughter-dam
comparisons were made and the transmitting abilities of the bulls
were not considered*
Yapp (I6 J4.) reported on the records of the and cows in the
Bowlker herd made after the herd was moved to the University of
Illinois* The records were made in the first lactation, and were for
a period of h$ weeks. All of the cows freshened at approximately the
same age* Forty-seven F^ generation females averaged 313 pounds of
butterfat, compared with a 3 0 1 -pound average for their 38 generation
daughters. Campbell and Yapp (13) studied the size of the fat globules
in the milk of the Bowlker crossbreds, also in the milk of purebred
Guernseys and Holsteins. It was found that fat globules in the
Guernsey milk were from 1B to 20 per cent larger than those in
Holstein milk. The size of fat globules in milk from the F-^ and Fg
generation crossbred cows was intermediate between the parental breeds*
Ellinger (U2, U3)» in studying the data from the crossbreeding
experiment in the Tranelcjaer herd, found that 75> Jersey x Red Danish
crossbreds averaged 36 kg. of butterfat in the first 70 days of the
first lactation. A group of 2^0 Red Danish cows averaged 32 kg. and
liiO daughters of the Jersey sires averaged 37 kg. of butterfat on
the same basis. Twenty three-fourths Red Danish cows averaged 3>h kg.,
seventy-five three-fourths Jersey cows averaged 36 kg. and twenty-five 67 seven-eighths Jersey cows averaged 32 kg. of butterfat. As stated in the discussion of milk yield* Ellinger concluded that the cross breds were intermediate between the two parental breeds, and the backcrosses intermediate between the crossbreds and the parental breed used to make the backcross. Robertson (12U) stated that the design of this experiment was adequate for a test of heterosis. The
F]_ generation was very close to the mean of the parental breeds, and
Robertson concluded that heterosis had not been shown.
The butterfat production of the parent breeds and the crossbreds in the Alaskan crossbreeding experiment was reported on by Alberts (1) and White (152) . The two highest Holsteins produced I467 and h33 pounds of butterfat. One crossbred produced b75> pounds of butterfat in 1930, and $30 pounds in 1931* Two other crossbreds produced U6 I4. and 5lU pounds of butterfat in 1931. According to Gasser (50) one of the crossbred cows produced 5 8 U pounds of butterfat in 369 days.
Butterfat records were reported by Olson (105) for three of the crossbreds at the South Dakota station. A Holstein x Jersey produced
3$k pounds of butterfat in 12 months at two years and eight months of age, compared with 201 pounds produced by her Jersey dam in nine months at three years and nine months. Two Jersey x Holstein cows produced 193 and 5 U0 pounds of butterfat in ten and twelve months at two and two and one-half years of age. Their Holstein dams produced 3lU and 277 pounds of butterfat in 12 months at five years and one month and two years and three months of age.
Prentice (113) stated that the original 15 cows at Mt. Hope farm, which were Guernseys, averaged I4JJ4. pounds of butterfat, and their 7h daughters averaged J4.38 pounds. After some crossbreeding had been 68 carried on for 15 years, the herd averaged 552 pounds of butterfat*
These records "were on a twice—a-day milking, 305 day lactation, mature e quivale nt ba si s *
Byckov (12) reported that Ayrshire x East Friesian crossbreds on a state farm in the Moscow province averaged 158 kg* of butterfat in 300 day lactations. East Friesian and Ayrshire cows in the same herd averaged 135 kg. and llj.8 kg* of butterfat in 300 day lactations.
Fohrman et al* (U6) reported on the butterfat production of the crossbreds at Beltsville. On a 3x, 365 days mature equivalent basis,
55 foundation cows averaged 59U pounds, 55 two-breed crosses 799 pounds,
58 three-breed crosses 801 pounds, and 23 progeny of the three-breed
crosses averaged 800 pounds of butterfat. The standard deviations and coefficients of variation followed a pattern similar to those for milk production. The foundation cows were highest, the two-breed crosses
lowest, and the three-breed crosses were in between. The coefficients
of variation were 19*2, 9-U, and lU.O respectively for the foundation
cows, two-breed, and three-breed crossbreds. The conclusions regard
ing butterfat production were the same as for milk production.
Fohrman (U5) had previously reported that five crossbred bulls
were used in the project. They were bred to crossbred females. The
first bull, a Red Dane x Holstein, sired two daughters that averaged
650 pounds of butterfat in the first lactation. A three-breed bull
sired by a Red Dane bull, and from a Jersey x Holstein cow sired a
daughter that produced 586 pounds of butterfat in her first lactation*
Schmidt (127) reported that 12 Jersey x Friesian crossbreds
averaged l6U kg. of butterfat in their first lactations of 305 days.
Their Friesian dams averaged 108 kg* of butterfat in their first 69 lactations. The Jerseys compared with the crossbreds were 19 unrelated cows that averaged 133 kg* of butterfat* It has previously- been stated that Schmidt thought this average was too low, since the cows were not acclimated. The dams of the four Jersey bulls used averaged 219 kg. of butterfat. However, Schmidt thought the dams' records were not comparable to the records of the other groups because they were the average of several lactations for each cow. This is one of the few cases of crossbred dairy cattle being better than either parental breed. However, the Friesian dams were selected as medium producers of milk with low butterfat content, whereas the dams of the
Jersey bulls were good producers of milk and butterfat. Robertson
(12U), in his review of crossbreeding, stated that the design of the experiment caused a bias in the direction of the results obtained.
Nevertheless, he believed the results indicated that heterosis would
result from crossing Jersey bulls with Friesian cows.
Schmidt analyzed the data on the basis of the amount of butterfat
produced for each 100 kg. of live weight. The Friesian cows produced
an average of 22 kg., the crossbreds averaged 37 kg., the 19 Jerseys
averaged 35> kg., and the dams of the Jersey bulls averaged £ 8 kg.
butterfat for each 100 kg. of live weight. Schmidt found that the
average size of the fat globules in the milk of the crossbreds was
much closer to the average size of those In Jersey milk than to those
in the milk of the Friesian dams. Schmidt classified the globules
in all of the milks according to size. He found that there were no
globules in the Friesian milk as large as the largest globules in the
Jersey milk. The milk from the crossbreds contained nearly as large
a proportion of large globules as the Jersey milk. 70
Regan (118) and Ralston et al. (115) reported preliminary results obtained from tho incrossing of inbred lines of Holsteins at the
California station# Inbreeding was started in the University Holstein herd about 1931* using sire-daughter matings. Rutterfat production decreased with each generation of sire-daughter mating until females with a coefficient of inbreeding of 37#5 or above, produced, according to Ralston et al. (115)* 199 pounds less than the first-generation daughters or 206 pounds less than the foundation females, Regan (118) stated that the first nine incross heifers to freshen averaged 537 pounds of butterfat on a twice-a-day milking, 309 lactation mature equivalent basis. Ralston et al. (115) stated that the increase over the dams was 203 pounds, and the increase over the foundations cows 52 pounds of butterfat. In an attempt to determine the reason for the increase in production, the sire was being bred back to his own daughters. Preliminary results indicated that beterosis was involved.
The various matings that Woodward and Graves (160) made to test for heterosis have been discussed in the section on milk yield. As the trend in butterfat yield was similar to that for milk yield, whether or not heterosis was shown was not discussed in the previous section. Eleven inbred daughters of seven inbred dams averaged 376 pounds of butterfat, compared with lt-37 pounds of butterfat for seven daughters of the same dams sired by unrelated bulls. Only one inbred daughter was better than her maternal sister. Woodward and
Graves were not sure whether the difference in production resulted from the depression of production in the inbreds, heterosis in the outbreds, or to differences in the transmitting ability of the inbred sires and the unrelated registered sires• They thought the last 71 possibility was the probable answer, since six of the inbred heifers were sired by a bull that proved to be a poor transmitter for production.
In another comparison, 12 daughters of inbred grade cows that were sired by four unrelated bulls were compared with 12 registered daughters of the same bulls. The daughters of the inbred grade dams averaged 1*53 pottnds of butterfat compared with a weighted average of
1*91 pounds for the registered daughters. One of the bulls sired eight of the daughters of the inbred cows. They were compared to six of his daughters that were inbred. The outbred daughters averaged
1*38 pounds of butterfat compared with 1*39 pounds for their dams. The inbred daughters of this bull averaged 1*83 pounds of butterfat
compared with 1*1*2 pounds for their dams. The dams of both groups of
daughters produced at the same level, yet the inbred daughters were much better than the daughters of the inbred dams. There was no
evidence of heterosis. However, the value of the data is reduced because some of the daughters of the inbred dams had mastitis and
the registered daughters of this bull had shown evidence of late maturity. In addition, they used some second lactation records for
the registered daughters and first lactation records for the daughters
of the inbred dams*
Thompson et al. (ll*l*) have reported on the results obtained from
using Red Dane bulls in herds of various dairy breeds in the state of
Michigan. This was a grading up program, but the first cross is of
interest because the dams were Guernsey, Holstein, Jersey, Brown Swiss,
Shorthorn, and mixed cows. The foundation cows averaged 35l pounds of
butterfat as compared with 379 pounds for the first cross animals. 72
The difference was highly significant, (P<0.001), as were the increases for crossbreds from Guernsey, Shorthorn, Brown Swiss, and mixed cows.
The increase for the crossbreds from Holstein cows was significant,
(P 0.0^), but not for the crossbreds from Jersey cows. It was thought that the first cross cows produced at a higher rate than should be expected, and that the increase might have been partly due to heterosis.
Solids Hot Fat
Yapp (162) compared the protein, lactose, and ash content of milk from Fn and F cows in the Bowlker herd with the content of these 1 2 constituents in milk from purebred Guernseys and Holsteins* The
observations covered the first 180 days of the lactation of each cow.
The protein content of the Guernsey milk was 3*92 per cent and that of
the Holstein milk 3.10 per cent. The milk from the F-^ and F^ crossbreds
contained 3.43 and 3 »5l per cent respectively, which was approximately midway between the parental breeds. Very little segregation was
observed in the 7^ generation and Yapp concluded that several genes
were involved in the inheritance of protein. There -was little differ
ence in the lactose content of milk from the Guernsey, Holstein, and
crossbred cows. The percentages were: Guernsey 5*10, Holstein 4.92,
cows 5®01 and cows 4.99* It was concluded that if the character
was inherited in a Mendelian manner, it was definitely established and
the genes close to being homozygous. The ash contained the soluable
and insoluble forms. Milk from the Guernsey and Holstein cows
contained 0.7540 and 0.6836 per cent ash respectively. Milk from the
F-^ and F2 cows contained 0*7314 and 0.7189 per cent ash respectively.
The F^_ generation was intermediate with a tendency toward the Guernsey 73 parent, and the Fg was intermediate between the parental breeds.
There was no greater variability in the Fg than in the parental breeds, and Yapp concluded that a number of genes were involved in its inheritance•
Chemical analyses of the irtilk of the crossbred cows in the
Wisconsin crossbreeding project (25) were made for some time, but no details have been published.
Schmidt (127) found that the Jersey x Friesian crossbreds in the German crossbreeding experiment averaged 110 kg. of protein in their first lactations in 305 days, and their Friesian dams averaged
108 kg. under comparable conditions. Nineteen Jersey cows used for comparison with the crossbreds averaged 91 kg. of protein, and the
Jersey dams of the sires of the crossbreds averaged 139 kg. On the basis of production per 1 00 kg. of live weight, the crossbreds produced 21 kg., the Friesian dams 2k kg., the 19 Jersey cows 2k kg., and the dams of the Jersey sires, 37 kg. In this experiment the crossbreds produced an average of 152 kg. of lactose, the Friesian dams 155 kg., the 19 Jersey cows 108 kg., and the dams of the Jersey sires 152 kg. On the basis of the amount produced per 100 kg. of body weight, the different groups averaged 33, 31, 29, and 111 kg.,
respectively.
Energy Yield, and Efficiency of Production
Gaines and Davidson (lj.9) in 1923 suggested that the gross energy value of milk is a better measure of yield than either total milk or butterfat. This deduction was made on the basis of the many investi
gations that had shown the existence of a significant negative 7k correlation between the two variables, percentage fat content of the milk and yield of milk. They concluded that percentage of fat of the milk is a factor affecting milk yield. The effect of butterfat percentage is that milk yield is inversely proportional to the energy value of the milk solids per unit of milk. The energy value of the milk solids, in the total milk yield, is a constant. These workers developed a formula by which the milk yields of cows could be corrected for the influence of fat content to the physiological equivalent of U.O per cent (fat) milk. The formula is:
F C M = 0.li H + 15 F where F C H is "fat-corrected milk," M is actual milk yi9ld, and F
is the actual fat yield expressed in the same units as milk yield*
Gaines (1|8) in 1928 presented further evidence for the use of
the gross energy value of the milk solids as a measure of the yield
of dairy cows. He tested the formula previously suggested (k9) on
data from experiments on the composition of milk and the nutritional
requirements of dairy cows, in producing milk containing varying
percentages of butterfat. The results showed that energy yield could
be estimated with reasonable accuracy from milk yield and butterfat
percentage. Taking the energy value of 1; per cent milk as 3k0 large
calories (instead of 330.6, used previously,) ( H9) , Gaines calculated
that the nutrients required for lactation (maintenance excluded)
per pound of milk are directly proportional to the energy value of
the milk. Gaines concluded that energy yield can be used as the
primary measure of yield, and the F C M formula is sufficiently
accurate for ordinary work.
Gaines (U8 ) determined the efficiency of production of per cent 75 fat-corrected milk by the Red Danish, Jersey, and crossbred cattle in the Tranekjaer (1*2, 1*3) herd. The data used by Gaines were from
Fredericksen (1+7) • Data on 368 Red Danish, 353 Jersey and 350 crossbred cows were available. The average age of each group of cows was between five and one-half and six years. The average amo+mt of 1* per cent fat-corrected milk produced by each group was 7,1+58 pounds for the Red
Danish, 6,02? pounds for the Jerseys, and 6,657 pounds for the crossbreds. The F C M produced per pound of live weight was 7»30 pounds for the Red Danish, 7*57 Tor the Jerseys, and 7.29 for the crossbreds. The amount of feod required to produce a pound of F C M was expressed in terms of Danish feed units, a Danish feed unit being equal to 2.2 pounds of barley or its equivalent. The Red Danish cows consumed 0.1+13j the Jerseys 0.1+12$ and the crossbreds 0.1+13 of a feed unit for each pound of F C M produced.
In analyzing the milk records from the Wisconsin crossbreeding experiment, Cole and Johansson (25) found that the calving interval varied a great deal. Because of this fact they used the milk yield
of the first 180 days of a lactation as the record for that lactation.
The milk yield in 180 days was converted to a 1+ per cent fat-corrected milk basis. When there were complete records for a cow’s first three
lactations, the average was used as her producing ability. When the
number of lactations was less than three, the yield was age-corrected.
The factors used were developed from the first three lactations of
10 cows representing all breeds and crosses in the experiment.
Cole and Johansson compared the F-j_ and Fg Jersey x Angus cows
with four Angus and two Jersey cows. The relationship of the purebreds
to the crossbreds was not made clear. The average number of pounds of 76 milk for each group were as follows: four Angus cows 2,030; two
Jersey cows 14,5 2 8 ; four Fq_ Jersey x Angus cows 3,11*75 an<^ four
Jersey x Angus cows 3,629. The average of the F]_ generation was' '3 low the average of the twro parental breeds. The five Angus cows and ' :ne six Holstein cows compared with the F^_ cows of this cross average’1-
2,906 and 5,599 pounds of milk respectively, nine Angus male x
Holstein female crossbreds averaged U,lt95 pounds of milk while ei" 3at cows from the reciprocal cross (Holstein male x Angus female) averaged
3,800 pounds of milk. Fourteen Fg cows averaged 3,689 pounds of : ;ilk.
The difference between the two groups representing reciprocal cro' ses was not significant. Cole and Johansson stated that most of the • cows were intermediate to their parents in milk yield, but that I'--.ere was considerable variation. Cole and Johansson found no signified jnt difference in variation between the F^ and F2 generations.
Schmidt (127) found that the milk of Jersey x Friesian croafv ?reds contained 8U3 calories per kilogram compared with 6ijl|. calories a kilogram of milk produced by their dams. The crossbreds consumor!
12 per cent more starch and 18 per cent more protein than their ct^srns •
Persistency of Production
Yapp (I6I4) found that F-^ cows from reciprocal crosses of tho
Guernsey x Holstein breeds were more persistent than the F2 fron
cross, from the 30th to the U5 th week of the lactation.
Ellinger (U3) studied the lactation curves for milk yield "the
cattle in the Tranekjaer herd. The data consisted of averages fo^sr the
different groups and covered a period of itl weeks. The Red Daait.iL
cows had the highest yield at the start and maintained it thro^^ut, 77 whereas the purebred Jerseys were lowest at all times. The crossbreds were intermediate, and the three-quarter Red Danish were more like the
Red Danish cows. The three-quarter Jerseys were more like the purebred Jerseys.
Cole and Johansson (25) found that the average lactation curve for seven Holstein x Angus cows was intermediate between the two pure breeds until the seventh month, after which it was closer to the
Aberdeen-Angus. The data from five Holstein and four Angus cows were used to obtain curves for these breeds. The Holstein cows differed from the Angus more in the level of yield than in the shape of the curves. The Angus cows had a shorter lactation and a longer dry period.
Fohrman et al* (1*6) reported that the two-breed and three-breed crossbreds in the Eeltsville herd were more persistent than the purebred foundation cows.
Length of Gestation
White (153) studied the gestation lengths of the to F^ generation calves from reciprocal crosses of the Holstein and Galloway breeds. The F^, F2 * and F^ generation males averaged 28lw7*
281.2, 281.8, and 28U.2 days respectively. The females of the F-^, F^,
F^j and generations averaged 283.9 * 282.5, 2 8 3 .2 , and 286.6 days respectively. White concluded there were no significant differences between sexes or between the calves of the first four generations of crossbreds.
Cole and Johansson (25) found that six male calves sired by
Angus bulls and from Holstein cows averaged 281.2 + 3.97 days in 78 utero, as compared with an average of 277*6 + 6,90 days for seven male calves from the reciprocal cross. The average for the 13 F-^ generation calves was 279*2 + £.76 days. Nineteen F2 generation calves averaged
278*6 + 5*61) days. Eleven female calves from the Angus male and
Holstein cow cross averaged 279.2 + 6.68 days in utero, x^hereas 11 females from the reciprocal cross averaged 276 .U + 5*37 days. The 22 calves averaged 277*8 + 6 .15 days in utero. Twenty-three genera tion females averaged 2 7 8 .0 + 6*02 days in utero.
Weight at Birth
White (153) found that 21 generation Holstein x Galloway crossbred calves (both sexes) averaged 87*7 pounds at birth. Calves from the reciprocal crosses made up the group. The Fg generation calves, 36 in number, averaged 82.1). pounds at birth. Thirty-eight
F^ and ten Fj^ generation calves (both sexes) averaged 90.6 and 83.6 pounds at birth. Forty-eight calves of both sexes sired by F^ generation bulls from crossbred cows averaged 83*7 pounds at birth.
Thirty calves of both sexes sired by generation bulls averaged
9U.0 pounds at birth. White thought that the difference between calves sired by F^ and F^ generation bulls might be significant.
Cole and Johansson (23) found that male and female calves from mating Angus bulls with Holstein cows were heavier at birth than the calves sired by Holstein bulls and from Angus cows. The male calves from the two crosses averaged 81)..5 + 1 0 .71* and 82.0 + 11.12 pounds, the difference being 2.5 + 6.07 pounds. The female calves from the two crosses averaged 73.9 + 10.66 and 69*5 + 11*98 pounds, the difference being 6.1* + U.83 pounds. The differences were not 79
significant. Nineteen F^ generation male calves averaged 19,3 + 9.71 pounds, and 23 F^ generation female calve3 averaged 71*0 + 11*29 pounds. Mien the sum of squares within groups x^ere pooled, eliminating
differences between reciprocal crosses and the sex groups, the standard
deviation in birth weight for the F^ generation was 11.20 and for the
F2 generation 10.61. Cole and Johansson concluded that there was no
evidence of increased variation of birth weight in the Fg generation
calve s.
Schmidt (127) found that two Jersey x Friesian crossbred calves
averaged 32 kg. compared with an average of 3i* kg. for i+O Friesian
calves and an average of 26 kg. for two Jersey calves.
Hilder and Fohrman (6$) compared the birth weights of crossbred
and purebred calves born in the Eeltsville herd. The objective of
the analysis was to determine if the crossbred calves showed heterosis
at birth. The method used in determining whether or not heterosis
existed was to compare the average of the crossbred calves with the
mean of the two parent breed averages for birth weight. The purebred
calves used to establish the breed averages were outcross calves.
The mean of the two parent breed averages was called the "expected"
weight. The difference between this mean and the average of the
crossbred calves was tested for significance by use of the t-test.
If the crossbreds were significantly heavier than the expected weight
it was thought that heterosis existed.
Eight female calves by Jersey sires and from Holstein dams
averaged 76.6 + 2.63 pounds, which was 1.10 pounds more than the
expected weight. Ten female calves from the reciprocal cross averaged
7U*9 + 2 .1;7 pounds, which was 0.60 pounds less than the expected 60 weight* Neither of these differences was significant. There was more
difference between the weights of male calves from these crosses than
between the female calves. Seven Holstein x Jersey males averaged
76.3 + 2.37 pounds, and six calves from the reciprocal cross averaged
82.0 + 3.87 pounds. The difference between these two groups was not
statistically significant. Thirteen female calves from reciprocal
crosses of the Red Dane and Holstein breeds averaged 9U.0 + 3.06
pounds at birth, which was 5*70 poimds more than the expected weight.
The difference was not significant. Eight female calves from
reciprocal crosses of the Red Dane and Jersey breeds averaged 70.5 +
2,95 pounds, which was 2.50 pounds more than the expected weight.
The difference was not significant. No group of crossbred calves
showed heterosis for birth weight when compared with the mean of the
two parental breeds.
Touchberry and Tabler (lU6 ) analyzed the birth weights of calves
from reciprocal crosses of the Guernsey and Holstein breeds and their
purebred relatives. They found that the crossbreds were 2.6 pounds
heavier than the purebreds as indicated by the breed of sire by breed
of dam interaction.
Martin (97) analyzed the birth weights of crossbred calves
produced by mating animals of the Red Dane, Red Poll, and Milking
Shorthorn breeds in all possible combinations. The crossbred calves
averaged 1.9 pounds heavier than the purebred calves.
Ralston et al, (115) reported that when an unrelated inbred bull
(F=2 3 ) was bred to inbred females, whose coefficients of inbreeding
averaged 2 9 .8 , the calves were 1 3 .1+ pounds heavier at birth than their
dams and 6.2 pounds heavier than the foundation cows at birth. 81
Growth and Size at Maturity
Data on the growth of crossbred animals and their parents, when
at least one parent was a dairy animal, have been published for only
a few crossbreeding experiments. Data from more experiments are
available on the mature size of animals involved.
In the Wisconsin (25) crossbreeding experiment, the calves were
weighed at birth and then at weekly intervals. Several measurements were made at one and four weeks of age and then at four-week intervals
up to one and one-half years of age. Measurements were then made at
twenty-one and twenty-four months of age and each year thereafter.
The average heart girth measurement of F^ generation females from the
Holstein male x Angus female cross was consistently greater than that
of the females from the reciprocal cross except at birth. The
difference increased until twelve months of age when it became
significant. Cole and Johansson thought this remarkable because the
Angus cows had smaller heart girths than the Holstein cows. Data were
available for heart girth measurements on 12 F-^ and 16 Fg females from
the Angus and Holstein cross from birth to four years of age. The
growth curve for the F-j_ cows was closer to the Kolsteins than to the
Angus. The heart girth measurements for the F^ generation were
consistently less than for the F^ generation. The difference between
the standard deviations of the two groups was not significant*
Cole and Johansson also presented data on the mature 3ize of the
different groups in their experiment. Seven Aberdeen-Angus cows
averaged 1,265 pounds in weight, l5l cm. in body length, and 122 cm.
for height of withers. Two Jersey cows averaged 1,015 pounds in
weight, and lUU and 126 cm. for the measurements. Four F^ Jersey x 82
Angus cows averaged 986 pounds in weight, lU8 and 120 cm. for body length and height of withers. Four F^ cows of this cross averaged
1,0U5 pounds in weight, lUU and 120 cm. for body length and height of withers. The F^ had the same average body length as the Jerseys, and both the F^_ and F^ were shorter at the withers than either the
Angus or Jersey cows. The six foundation Holstein cows averaged
1,293 pounds in weight, l6l cm. for body length, and 132 cm. for height at withers. Seventeen F-j cows from the Angus x Holstein cross averaged 1,322 pounds in weight, 159 cm. in body length, and 130 cm. for height at withers. Fourteen F2 cows from the same cross averaged
1,29^ pounds in weight, 1$% cm. for body length, and 128 cm. for height at withers, While the F^ and F^ generation animals were between the parent breeds for body length, and height of withers, the F^ was heavier than, and the F^ equal to the foundation Holstein cows.
Schmidt (127) found that Jersey x Friesian crossbred females were consistently lighter than Friesian females at the same ages.
Jersey females were consistently lighter thanthe crossbreds except
at six months of age. At forty-five months the crossbreds averaged
lihB kg. and the Friesian cows averaged $06 kg. at the same age.
Weights at the same age were not available for the Jerseys; however,
weights taken between four and five years of age averaged 392 kg.
Schmidt made the following measurements of the crossbreds and
animals of the two parent breeds: height at withers, height at
sacrum, length of trunk, heart girth, chest width, chest depth, hip
width, rotator muscle width, and girth of the shank bone. The
measurements were made at six months, one, two, three, three and 83
three-fourths years, and maturity. Measurements were given on all
groups only through two years of age, and fox* the Friesians and cross
breds through three and three-fourths years. There was little
difference between the crossbreds and Friesians for height at
■withers, sacrum height, and length of trunk; however, both groups
were larger for these parts than the Jerseys. The measurements for
heart girth were not so consistent; at six months the Jerseys
averaged 115 cm., the Friesians lllx cm., and the crossbreds 113 cm.
At two years the crossbreds and Friesians averaged 16U cm., and the
Jerseys 155 cm. At three and three-fourths years of age the Friesians
averaged 181| cm., and the crossbreds 175 cm. Through two years of
age the chest width measurements were in the order of Friesians,
crossbreds, and Jerseys. At three and three-fourths years of age
the chest width of the Friesians was I4.2 cm., that of the crossbreds
38.5 cm. All three groups had the same depth of chest measurement of
61.0 cm. at two years of age. At three and three-fourths years the
crossbreds had 0.5 cm. greater depth of chest than the Friesians.
The magnitude of the measurements of the hip width, rotator muscle
width, and shank bone girth were in the order of Friesians, crossbreds,
and Jerseys. The Friesians and crossbreds were close together, with
the Jerseys being smaller in these measurements.
Hilder and Fohrman (65) studied the growth of the F^ generation
crossbreds in the Beltsviiie herd in comparison with animals of
their parental breeds. The data were for the first eighteen months
of the life of the crossbreds. The calves were weighed at birth and
at 30-day intervals thereafter up to twelve months of age. From then
on, the heifers were weighed the first day of each month, and this 8h weight was used as the weight for the nearest age unit to the date on which the weighing was made. Five measurements were obtained at six, twelve, and eighteen months of age0 These measurements were: height at withers, width of fore chest, depth of fore chest, width of hips, and the total length from the withers to the pin bones. Weights and measurements of purebred animals at the same ages were available for comparison. The average of the weight or measurement for a group of crossbred calves at a certain age was obtained. The average of each of the parental breeds was calculated and a mean of the averages then obtained. This mean was called the expected weight or measurement.
In order to determine whether or not heterosis was shown, the average of the crossbreds was compared xith the expected value and a test of significance xised to see if the crossbreds xjere significantly heavier or larger in the body part being compared. The t-test was used as the test of significance.
The calves from Holstein dams sired by Jersey bulls weighed less during most of the period from one to eighteen months of age than the expected value. Eight heifers averaged 785.5? + 12.60 pounds at eighteen months of age compared with the expected value of jQh^k pounds. The crossbreds were lighter at each monthly age than the purebred Holstein dams. The calves from Jersey cows and sired by
Holstein bulls weighed slightly less than the expected value at birth, one and two months of age. Beginning at three months of age the cross breds were heavier than expected each month up to eighteen months of
age. From four through nine months of age, the difference was either
significant or highly significant. The crossbreds were 37*8 pounds
heavier than expected at eighteen months of age, this difference 85 being significant. On the basis of the criteria for heterosis set up by Hilder and Fohrnan, it existed in seven different months.
Compared with their Jersey dams the crossbreds were heavier each month, from birth to eighteen months of age.
The data on skeletal growth for calves from reciprocal crosses of the Holstein and Jersey breeds were similar to the data for body weight. The calves from Holstein dams and sired by Jersey bulls varied little from the expected values, being slightly above or below
for each measurement at six, twelve, and eighteen months of age.
Calves from the reciprocal cross exceeded the expected value in all
comparisons except one. At six months of age the crossbreds exceeded
the expected value for each measurement. The differences for height
at withers and width of hips were significant, whereas those for
depth of fore chest and total length were highly significant. At
twelve months of age the differences for total length and width of
hips were significant and highly significant respectively. At
eighteen months only one difference was significant, that being for
width of hips.
The calves from reciprocal crosses of the Holstein and Red Dane
breeds were considered as a group. When the monthly averages for
body weight were compared with the expected values, the crossbreds
exceeded these values fifteen out of eighteen of the months, beginning
with the second month. However, none of the differences were
significant. Eight of the crossbreds averaged 877*0 + lU.36 pounds
at eighteen months of age, compared with 8 6 5 .1 pounds, the expected
value. These calves varied little from the expected values for body
measurements at the three ages measured, but exceeded the expected 86
value in all except three cases. However, the differences were so
small that none of them were significant.
Calves from reciprocal crosses of the Jersey x Red Dane breeds
were also considered as one group. From the second through the
eighteenth month, the averages of the crossbreds for body weight
were greater than the expected values, but the differences were not
significant. Seven crossbreds averaged 765.7 + 28.62 pounds at
eighteen months compared with the expected value of 7^0*0 pounds.
Sody measurements were given only fcr the calves by Red Dane sires
and from Jersey dams. The crossbred calves exceeded the expected
values for all measurements at the three different ages, but none of
the differences were significant.
Hilder and Fohrman concluded that there was some indication that
the crossbreds tend to be slightly larger than the average of the
parent breeds. According to the criteria set up, heterosis was
shown by some of the groups at different ages, but heterosis was not
the general rule.
Hilder and Fohrman stated that some breed interactions were
evident. The Holstein x Jersey crossbreds grew most rapidly from
four to eight months of age, whereas the Red Dane x Jersey calves
grewT uniformly from the second month on. The rate of growth of pure
bred Holsteins was relatively faster than that of Red Danes for the
first twelve months, then the Red Danes gained at a relatively faster
rate from twelve to eighteen months. "When Guernsey cows were crossed
with bulls from these two breeds, the crossbreds did not follow the
trend of the breed of the bull. The higher early rate of growth was
attained by the Red Dane x Guernsey crossbreds, whereas the Holstein x 87
Guernsey crosses grew relatively faster in the later period.
Kirchner (80) reported on the weights of crossbred cows sired by a Guernsey bull and from cows of different breeds. One Guernsey cow which weighed 366 kg. was available for comparison. Three crossbreds
sired by the Guernsey bull from East Friesian, Ereitenburger, and
Pinzgauer cows weighed 592, 56?, and U9U kg. Their dams weighed 720,
7h0, and 538 kg. respectively. A purebred daughter of the East
Friesian cow weighed 761 kg. Gaines (U8) reported that 350 crossbred
cows in the Tranekjaer herd averaged 913 pounds at five and eight-
tenths years of age, whereas 368 Red Danish and 353 Jersey cows in
the same herd averaged 1,021, and 796 pounds respectively at approxi mately the same age.
Eyckow (12) reported that Ayrshire x East Friesian crossbreds
averaged U76 kg. at the first calving, compared with U65 kg. for
Ayrshires, and 1*81 kg. for East Friesians.
Body Type
Most of the information on the body type of crossbreds comes
from those experiments in which beef cattle were crossed with dairy
cattle. Gowen (5U) studied the type of the crossbreds in the Maine
experiment. In this experiment animals from several dairy breeds
were crossed, and dairy cattle were crossed with animals of the
Aberdeen-Angus breed. Gowen thought that the body could be divided
into four general regions, which would show beef or dairy form.
These regions being the head, fore quarters, barrel, and hind
quarters. In this experiment the dairy and beef types blended to a
considerable extent in the F-j_ generation. However, it was possible 88 to determine that one type was dominant, and the other recessive in many of the crosses. The beef type was pronounced in the head and fore quarters. The dairy type predominated in the barrel and hind
quarters. The heads of crossbreds with Angus inheritance were shorter
in length, and broader between the eyes than crossbreds of dairy breeds
of the same age. The girth at the last rib of the Angus crossbreds was greater, as was also the width of the brisket. Measurements of
the hind parts of the body showed there was no change from the general
form of the dairy crossbreds, except for a slight shortening of the
rump. Gowen concluded that crossing with the Angus breed improved
the beef type of the fore quarters without influencing the hind
quarters to any extent.
Kuhlman (81) studied the type of Aberdeen-Angus x Jersey
crossbreds in a herd in England owned by Francis B. Samuelson* The
cross was made by using an Angus bull and Jersey cows. The F^
generation cows resembled the Angus breed in that they were beefy in
conformation. They had udders which were uniform and of good size,
and Kuhlman stated that they seemed to be good dairy cows. The F^
generation showed much uniformity, but the F^ generation showed
marked variation in conformation.
Cole and Johansson (2f?) concluded that the type of the F^
generation from crossing the Angus breed with the Holstein and Jersey
breeds was more or less intermediate to the parental breeds. No
evidence of increased variation in the Fg generation could be
established. In this experiment the cows were scored on the basis
of "dairy qualities." The Aberdeen-Angus cows scored 71*0 per cent,
the Jerseys 89*0, and the Holsteins 82.3 per cent. The F-^ Jersey x 89
Angus cows scored 83.U per cent, with the F^ cows of this cross
scoring 78.6 per cent. The F^ Holstein x Angus cows scored 7U.6, and the F^ cows of this cross 73.5 per cent. On udder alone the
Angus cows scored 62*3, the Jerseys 85.0, and the Holsteins 7^.9
per cent. The Holstein cows were of poor type. The F^ and F^ Jersey x Angus cows scored 82.2, and 71.1 per cent respectively. The F-^ and
Fg Holstein x Angus cows scored 67.9, and 61;.0 per cent respectively on udder.
Cole and Johansson (26) found that the long and relatively
narrow, primigenius type of skull of the Holstein was dominant in
the F-^ to the shorter, brachycephalous skull characteristic of the
Aberdeen-Angus breed. There was some evidence of segregation in the
Fg generation.
Black (5) reported that the Galloway x Holstein crossbreds in
the Alaskan experiment had the appearance of a beefy dairy cow, with
greater spring of rib and more flesh than the Holstein. They
represented a blending of the characteristics of both parents in all
points of conformation, with the exception of width of withers, heavy
shoulders, and forelegs. In these characteristics they resembled the
Galloway.
There is a scarcity of information on the type of crossbreds
from crosses of animals of two dairy breeds. Yapp (163) found that
the F-j_ generation crossbreds in the Bowlker herd were intermediate
between the two parental breeds. The F2 generation cows were variable
with the extremes approximating the parental types* Olson (10U)
found that heifers from reciprocal crosses of the Holstein and Jersey
breeds were smaller and more refined than purebred Holsteinsj however, 90 they did not show the refinement of purebred Jerseys.
In crosses of Jersey bulls with Friesian cows, Schmidt (127) found that the crossbreds carried more flesh than the Jerseys, but carried less flesh and had a finer bone than the Friesians. The crossbreds showed more dairy character than the Friesians and had udders which were characteristic of the Jersey breed. Byckov (12) reported that when an Ayrshire bull was crossed with East Friesian females the F^ generation resembled the East Friesians in type but were more compact.
Measures Used to Determine Heterosis _ Other Classes of Live Stock
Swine
Roberts and Carroll (123) reported in 1939 on the results from double mating Duroc Jersey and Poland China sows with boars of their
own breed and also the other breed. The characters studied were birth weight, strength at birth, mortality before vaccination, weight
at beginning of the feeding test, average daily gain, feed per 100
pounds of gain, and weight near market age. Birth weights of the
purebred and crossbred pigs were analyzed by three different methods.
The first method used was to compare all purebred pigs with all
crossbred pigs, whether born in single or mixed litters. The mean
birth weight of the purebred pigs was 2.62 + 0.02 pounds compared
with 2.61; + 0.02 pounds for the crossbred pigs. The difference was
not significant. By the second method, the average weights of purebred
and crossbred pigs of the same sex and litter were compared by an
appropriate statistical test. The only significant difference found 91
was between purebred and crossbred females from Poland China sows x
Poland China and Duroc Jersey boars* In this case, the average weight of the purebreds was 2 .61 + 0.05* and of the crossbreds 2.90 +
0.06 pounds. In the third method, a purebred and a crossbred pig of
the same sex were selected at random from the same litter, the number
of pairs being 18U* The average birth weights for the purebreds and
crossbreds were 2.63 and 2.76 pounds respectively. The mean difference
of 0.1299 pound in favor of the crossbreds was significant*
Roberts and Carroll found that 3»7 per cent more of the crossbred
than purebred pigs were graded "strong" at birth, also 2 per cent
less of the crossbreds were graded "medium." The percentage of weak
pigs was slightly higher for purebreds, but the percentage of pure breds farrowed dead was lower. The data from the feeding tests were
analyzed by comparing the average of the purebreds with that of the
crossbreds from the same litter. Pigs from 20 mixed litters were
used, and the average daily gains were 1.99 and 1.65 pounds,
respectively, for purebreds and crossbreds. The difference was not
significant. The purebreds required Ij.09 pounds, and the crossbreds
Ii.02 pounds of feed for 100 pounds of gain* The difference was not
significant. In all comparisons of purebred and crossbred pigs, the
differences were in favor of the crossbreds but only birth weight was
significantly in favor of the crossbreds.
Lush et al. (9k) reported on the results obtained by double
mating sows in eight different years. They also reported on a
comparison of Landrace x Poland China crossbreds with purebred
Poland China and Landrace pigs. The purebred and crossbreds from
the double matings were compared on a within year basis. These 92
workers found that the percentage of stillborn pigs was smallest for the crossbreds, and that the crossbreds were more vigorous at birth, as shown by their ability to survive until weaning age. The cross bred pigs averaged three to four pounds heavier at weaning time, and
the crossbred litters were heavier at weaning, partly because of the larger pigs and partly because the crossbred litters contained more pigs. The crossbreds gained 0.09 to 0.12 pound more per day in the
feed lot than the purebreds, and reached a weight of 229 pounds on
25 to 30 pounds less feed than required by the purebreds*
Winters et al. (199) in 1939 made the first report from the
Minnesota Station on the crossbreeding of swine. The results of
several different crosses were reported. The crossbreds were compared with purebred pigs from dams which were as similar to the dams of the
crossbreds as it was possible to get them. Two-breed, three-breed, and back-cross animals were produced. The method used in comparing
crossbreds with purebreds was to express the advantage or disadvantage
of the crossbreds over the purebreds in per cent. The characters
studied to measure heterosis were as follows: (l) birth weight of individual pigs, (2) birth weight of the live pigs in a litter,
(3) number of live pigs per litter, (U) total number of pigs per litter, (9) number of pigs weaned per litter, (6) litter weight at weaning, (7) saving in feed, and (8) saving in time to reach 220
pounds live weight. The two-breed pigs were superior to the purebreds
for all characrers, the per cent advantage for the different characters
ranging from 1.96 for birth weight of individual pigs to 2U.81p for
litter weight at weaning. The advantage in feed saved was 2.99
per cent; and for time saved in reaching 220 pounds of live weight, 93
the advantage was 8*67 per cent. The three-breed pigs were superior to the purebreds for all characters, the per cent advantage ranging from 0.39 for birth weight per live pig to 60.76 for litter weight at weaning.
The three-breed pigs showed more advantage over the purebreds than the two-breed pigs for all characters except birth weight per pig and the length of time to reach 220 pounds live weight. The back-cross pigs were inferior to the purebreds for number of live pigs and total number of pigs per litter. These pigs showed more advantage over the purebreds than two-breed or three-breed pigs for birth weight per live pig and in length of time to reach 220 pounds live weight.
In 19U2 Carroll and Roberts (II4.) published an analysis of the data available on the crossbreeding of swine. As a standard they used the one proposed by Lambert (8 3 )* This meant that for any character studied the crossbreds had to excel the pigs from both parental stocks. Their argument was that if the crossbreds excelled only one of the purebreds and were inferior to the other, then they must be considered a blend of the two purebred lines with no evidence of heterosis. Carroll and Roberts stated that - - the advantage in crossbreeding could show up in a large number of pigs farrowed per litter; in heavier pigs at birth; in more vigor and survival of pigs; in larger pigs at weaning; or in ability of the pigs to make more rapid and economical gains. In the case of four of the above six factors, the average value for the crossbred pigs was intermediate 9k
between the values for the two pure breeds. The average percentage of survival of the crossbred pigs equaled that of the best purebreds.
The average daily gain of all crossbred pigs was slightly above that of the more rapidly gaining purebreds. Carroll and Roberts concluded that the data did not support the belief that heterosis could be expected in the majority of crosses between breeds of swine. They thought that in most cases a grading up process had occurred, the poorer purebreds being graded toward the better purebreds*
Winters et al. (1E>8) made a preliminary report on the crossing of inbred lines at the Minnesota stations. Seven inbred Poland China lines were used to make eight different line crosses, and three lines belonging to three different breeds were used to make five crosses between breeds. The lines except for the Minnesota M line (Fx.,0*72) were not highly inbred when compared to inbred lines of corn and laboratory animals. However, the lines were more inbred than outbred swine of the breeds represented.
Samples of both inbred lines were raised with the crossbreds.
Gilts were used as dams, and it was planned to use two or more sires from each line. Five basic factors of performance which affect econony of production were used to compare pigs of the inbred lines with the crossbred pigs. These factors were the (1) number of pigs born alive,
(2) survival, (3) rate of gain, (U) economy of gain, and (5) score for body conformation. Each cross was an experiment, and in each experi ment the advantage or disadvantage of the crossbreds, in comparison with the average of the parental stock was calculated for each of the five factors in terms of per cent. The results were then added for each cross and divided by five to give the over-all advantage or dis advantage in performance for each group of crossbreds. Twelve out of the 13 crosses possessed more vigor than the average of the parental lines.
The crosses were grouped according to the decrease in the coeffi cient of inbreeding of the crossbreds, as some of the inbred lines were related. A decrease in inbreeding was accompanied by an increase in vigor. Line crosses between the breeds showed more increased vigor than the line crosses within a breed. These workers thought this demonstrated the advantage of genetic diversity between parental stocks.
A comparison was made between crosses from non-inbred purebreds
(159) and crosses from inbred purebreds within and between breeds (158).
The data from both experiments were calculated to the same basis, except that score on body conformation was omitted as it was not available from Winters et al. (15>9). Two-breed, back-cross, and three-breed pigs were 6.3* 7.5* and 11.7 per cent better than the average of their parental lines. Pigs from inbred lines within a breed showed 10.6 per cent advantage over the average of the parental lines, whereas those from inbred lines of two different breeds showed 19.9 per cent advantage over the average of the parental lines.
These workers (158) stated that the practical question is not how much the crossbreds exceed the inbreds, but how they compare in perfor mance with good non-inbred swine. No non-inbreds were maintained for 96 this purpose, so performance of the crosses •was compared, with the per formance of what was believed to be superior outbreds. Data on the out- breds were obtained from the literature. The items for which the dif ferent groups of pigs were compared were the (l) number of pigs weaned per sow, (2 ) average weaning weight per pig, (3 ) daily rate of gain and
(I4) individual pig weight at 180 days. The pigs from crossing inbred lines of different breeds were best; those from crossing inbred lines within a breed second; and the outbreds last for each item. The data from individual crosses indicated that the best performing crossbreds were most likely to be produced by the best performing inbred lines.
A more complete report on the crossing of inbred lines within and between breeds at the Minnesota stations was made by Sierk and Winters
(133). The average inbreeding of the lines ranged from 22 to approxi mately 75 per cent. The data were obtained during the period 19Ul to
19U7 inclusive, and represented 2,213 pigs in 373 spring farrowed gilt litters. Litters and pigs of the Minnesota No. 1 line, the Minnesota
No. 2 line, nine different inbred Poland China lines, crosses of the inbred Poland China lines, and different cross combinations of the three breeds were represented. The records were gathered at five different stations in the state of Minnesota. While environmental con ditions varied from year to year, and station to station, these workers stated that there was no reason to believe that the environment was more favorable to either the crosses or parental lines.
In this study, three measures of vigor were used; namely, (1) weaning weight, (2 ) rate of gain during the post-weaning period, and
(3 ) efficiency of feed utilization during the post-weaning period.
Since the relative values of the three factors had never been determined, 91 each was given equal value in appraising vigor. The age for weaning was fifty-six days and the feed requirement was corrected to a standard weight of 200 pounds. The method of comparing the crossbreds with the parental lines was the same as used in previous publications (158), (159).
The advantage or disadvantage of the crossbreds when compared with the
average of the parental lines was calculated for each of the measures
in terms of per cent. The results were added for each cross, and divided
by three to give the over-all increase or decrease in vigor for each
group of crossbreds. Similar types of mating were grouped together; for
example, the inbred Poland China line crosses included the two-, three-,
and four—line crosses.
Pigs from crosses of inbred Poland China lines showed an average
of 10.5 per cent increase in vigor over the average of their parents.
Pigs from crosses of inbred Poland China lines with the Minnesota
number 1 and 2 lines showed average increases in vigor of 18.2 and 12.U
per cent, whereas pigs from crosses of the Minnesota number 1 and 2
lines showed an increase of 21.0 per cent over the average of their
parents. Sierk and Winters compared the average performance of the bet
ter combining inbred line crosses with the average performance of non-
inbreds and non-inbred breed crosses, as reported by investigators from
a number of midwestern experiment stations and the United States Depart
ment of Agriculture. The inbred line crosses were heavier at weaning,
gained faster and used less feed per 100 pounds of gain than the non-
inbreds and non-inbred breed crosses. They averaged lLu? per cent
better than the non-inbreds and non-inbred breed crosses for the three
factors.
Sierk and Winters stated that results of their study indicated that 98
The manifestations of heterosis in swine are the same as would be ex pected by increasing the efficiency of metabolism. Also that they were the kind of results derived from a superior developmental system, and once such superiority has been established, its apparent degree may be increased as manifested by the fact that vigorous animals may be much less susceptible to the effects of varying environmental conditions*
The results were also interpreted as an indication of the importance of genetic diversity in relation to heterosis* The genetic aspects of this study have been discussed under Interaction Between Alleles*
Dickerson et al. (32) studied heterosis in crosses between inbred lines of Poland Chinas. Each boar sired several inbred and several single-cross litters, each of the single-cross litters being from a dam of a different inbred line. If possible, two sires were used from a line. This was done so that differences between lines could be dis tinguished from differences between sires belonging to the same line.
There were 28 intra-sire comparisons, including $6 inbred litters from
11 lines and 60 single-cross litters representing U3 different combina tions. Inbreeding of the litters averaged h2 per cent for inbreds, and
6 per cent for single-cross litters. Corresponding averages for the dams were and 28 per cent. The number of pigs born and alive at 21, £6, and 1Sh days of age were used as measures of viability. Individual weights at these ages were used as a measure of growth. Average daily gain, feed required for 100 pounds of gain, and certain carcass measure ments were studied. The mean differences between inbreds and single cross pigs by the same sire were used as the primary observations in ana lyzing the data.. The authors stated that by this method sire and line differences which affected both inbreds and single-cross pigs would be 99 eliminated. Each intra sire difference was weighted in proportion to the reciprocal of its variance. The difference between the means, of the single-cross pigs and inbreds, for each comparison, was adjusted to zero mean difference for age and inbreeding of dams, and then tested for significance•
It was found that heterosis or its converse, the effect of inbreed ing, was greater in viability than in rate of growth, although they were related in that the faster growing pigs were more likely to survive.
Mortality was less among crossbreds than among inbreds, both before and after birth, so that at five months of age the crossbred litters averaged one and four—tenths more live pigs than the inbred litters. The cross bred pigs were slightly heavier at birth and 21 days, three and four- tenths pounds heavier at 56 days, and 25 pounds heavier at l5U days. The crossbreds grew more rapidly from eighty—four days of age to a weight of 225 pounds, but required as much feed per 100 pounds of gain as the inbreds.
Chambers and Whatley (21) reported on the amount of heterosis ob tained in crossing inbred lines of Duroc swine. The purpose of the study was to determine whether selection within moderately inbred Duroc lines, followed by crossing of these lines resulted in improved perfor mance. All lines except one vrere less than 20 per cent inbred. The litter weights and number of live pigs at birth, 21, 56, and 180 days were the items used in comparing the various lines and crosses. Compari sons were limited to those which occurred within the same season. The method of analysis was that used by Dickerson et al. (32). Chambers and
"Whatley made the following comparisons:
1. Two-line crosses with inbreds from the same line as the dam 100
2. Two-line crosses with the average of the inbreds of the two
parental lines
3. Three-line crosses with two-line crosses
U. Three—line crosses with outbred Durocs
5. Two-line crosses with outbred Durocs
Heterosis was evident in the number of pigs per litter and litter weights at birth, and increased as the litters became less dependent upon the direct mothering ability of the dams. Heterosis was brought about more because of increased viability of the pigs and productivity of two-line-cross gilts than in increased growth rate of the individual pigs. Two-line cross litters raised by inbred sows were not superior to outbred Duroc litters. Three-line-cross litters, raised by two-line- cross dams, and sired by inbred boars of a third line, were superior to two-line-cross litters and outbred Durocs with which they were com pared. However, the differences were not statistically significant for all items. Because heterosis was expressed in both number of pigs which survived and the growth rate of the individual, Chambers and Whatley suggested that total weight of the litter be used to measure over-all performance for comparison of lines and crosses.
Beef Cattle
Phillips et al. (108) reported on a comparison of steers by Short horn bulls from Hereford cows, with purebred Hereford steers to determine if the crossbreds showed heterosis. The dams of the two groups were re lated. The experiment was conducted for two years and the data for each year were analyzed separately. Many items were compared, among them being birth weight, final feed-lot weight, feed lot gain, effi ciency of gain, slaughter grade, carcass grade and dressing percentage. 101
The differences between the means of the two groups fed out each year were tested statistically for significance. In both years the crossbred calves were heavier at birth than the purebreds. This advantage in creased with age* so that at the end of the feeding period the cross breds had surpassed the purebreds by 52 and 85 pounds for the two years.
These differences were significant at the 1 per cent level. The cross breds also gained faster than the purebreds each year. The differences were significant at the 1 per cent level. The differences found between the purebreds and crossbreds in efficiency of gain, slaughter grade, and carcass grade were not significant. The crossbred steers had higher dressing per cents, the difference being significant at the 5 per cent level one year, and at the 1 per cent level the other year. The cross bred steers had significantly less bloat than the purebreds*
Baker and Quesenberry (2) analyzed the data obtained on the heifers that were born at the same time as the steers reported on by Phillips et al. (108). As the two groups of heifers were kept for breeding pur poses the items studied were different than those for the steers. The heifers were compared for seven different items. Data for the animals bora in the two different years were combined, and analyzed by analysis of variance. The crossbred heifers excelled the purebreds and the differences were all significant at the 1 per cent level.
Gerlaugh et al. (52) reported on a crossbreeding experiment with
Aberdeen-Angus and Herefords conducted at the Ohio Station. Twenty- eight females of each breed were divided equally, one group being bred for purebred calves, the other group for crossbred calves. The next year the mating of the cows was the opposite of the previous year. The bulls were used for periods of two years. Eight crops of calves were born and were sired by five Aberdeen-Angus and four Hereford bulls.
An accident to an Angus bull made it necessary to use two bulls of this breed during one year. In the design of this experiment both crossbred and purebred calves by the same sire, could be compared in the same year. Theoretically, at the end of two years a bull would have sired a calf from each of the cows in the experiment, and each cow would have produced a purebred and crossbred calf. During each year purebred
Aberdeen-Angus and purebred Hereford and crossbred calves from reciprocal crosses were available for comparison. Thus, the groups were exposed to uniform environmental conditions in any one year. By obtaining crossbred and purebred calves from the same cow in successive years, the variation in the influence of the dam was limited largely, except for milking ability, to differences in genes which one calf received and the other did not. However, there would be differences in environment between years, between sexes if the calves were of opposite sexes, and between the merits of the purebred Aberdeen-Angus and Hereford bulls.
The calves were born from late July through the fall months. The first four crops of calves were barn fed, whereas the last four crops of calves were pastured the first summer after weaning, then finished in the feed lot. The crossbred calves from Aberdeen-Angus cows, both male and female, were heavier at birth than the purebred Aberdeen-Angus calves. The crossbred calves from Hereford cows were lighter than purebred calves from Hereford cows. The difference between crossbred calves of the reciprocal crosses was not significant. It was thought that the crossbred calves were more active and stronger at birth. Fewer crossbred than purebred calves died at birth or as young calves. The gain from birth to weaning was affected by the milking ability of the 103 damsj thus, a comparison of this item did not mean much. In analyzing the data for the feeding period the -weights of all calves were adjusted
to a similar average initial weight, and the length of feeding period
calculated to the same number of days* The crossbreds from the Aberdeen-
Angus cows made the most gain, followed by the purebred herefords and
the crossbreds from the Hereford cows* However, differences between
these groups were not significant* These groups gained significantly
more than the purebred Aberdeen-Angus steers and heifers*
In comparing the feed efficiency of the various groups, it was
found that the crossbred steers and heifers from Aberdeen-Angus cows
were more efficient than the purebred Aberdeen-Angus steers and heifers.
The differences were not significant. The purebreds from Hereford cows
were more efficient in use of feed than crossbreds from Hereford cows*
The differences were statistically significant. The crossbred steers
and heifers from the Aberdeen-Angus cows dressed slightly higher than
any other group. The steers and heifers from the Hereford cows were
the lowest of any group* The crossbreds from the Herefords dressed
slightly more than the purebred Aberdeen-Angus steers and heifers* The
crossbred steers and heifers from the Angus cows produced the highest
proportion of choice carcasses. The purebred Aberdeen-Angus steers and
heifer8 had the next highest proportion of choice carcasses, followed
by the crossbreds from the Hereford cows, and the purebred Herefords*
The differences between groups were statistically significant*
Sheep
Most crossbreeding experiments with sheep have been set up to
determine the relative value of rams of the mutton breeds when crossed
on Rambouillet ewes. Little work has been done on the problem of loli heterosis, or whether it even occurs when sheep of two breeds are crossed.
Horlacker (66) found that Iceland x Cheviot lambs weighed ten pounds more than purebred Cheviot lambs at eighty-four days of age. The difference in weight was attributed to differences in breed size, hetero sis, and the fact that more of the purebred lambs were twins.
Miller and Dailey (100) have reported on the crossing of different breeds of sheep at four University of Minnesota branch experiment stations during the year 19U2-U7. Many different crosses were made, but only those in which heterosis could be studied will be mentioned.
Shropshire ewes were mated to Columbia, Oxford, Targhee, Hampshire, and Border Leicester rams. Hampshire ewes were mated to Oxford rams, and Columbia ewes were mated to Hampshire, Suffolk, Shropshire, and
Targhee rams. As conditions varied between the four stations, direct comparisons were made only between matings at each station for each year.
The basis of comparison was the produc tiviiy per 100 pounds of ewe calculated as follows:
Productivity per ■ 100 x lb. Iamb + (lb. grease wool x 3.U) 100 lb. ewe Weight of ewe
Wool was corrected by the factor 3«U, because it had been found over an 18-year period that a pound of wool sold for 3«U times as much at the
Boston wool market as a pound of lamb at South St. Paul.
Miller and Dailey compared purebred Shropshire, Columbia and
Hampshire lambs with the crossbred lambs from ewes of these breeds. The
ewes of each breed produced more lamb per 100 pounds of ewe when their
lambs were crossbreds than when they were purebreds. The Shropshire
ewes produced 66 pounds of crossbred lamb per 100 pounds of weight
compared with 5h pounds of purebred lamb. The differences between the amounts of crossbred and purebred lamb produced by the Columbia and 105
Hampshire ewes per 100 pounds of ewe were nine and eight pounds respective' ly. The ewes of all three breeds produced 19 per cent more lamb per
100 pounds of ewe when used for crossing than when lambing purebred lambs.
This increase was due to faster growth rate of the Shropshire crosses and the greater number of crossbred lambs raised per ewe for all crosses.
The Columbia and Hampshire ewes had a slightly higher lambing percentage when their lambs were crossbreds. The crossbred lambs were hardier}
27.1* per cent of the purebred lambs born alive did not live to 11*0 days of age, compared with 19.1 per cent for the crossbred lambs. "When total productivity was calculated, the ewes of the three breeds with crossbred lambs showed 16 per cent greater productivity, than the ewes lambing purebred lambs.
Carter and Henning (15) studied the birth weights of 1056 lambs to determine whether heterosis was shown in the birth weights of crossbred lambs. The purebred lambs represented the Merino, Dorset, Hampshire,
Shropshire, and Southdown breeds. The crosses were Dorset x Merino,
Hampshire x Dorset-Merino, Southdown x Dorset-Merino, Shropshire x
Hampshire x Dorset-Merino, and Southdown x Hampshire x Dorset-Merino,
The average birth weight of the crossbreds was compared with the mean birth weight of the lambs of the pure breeds involved. If the average of the crossbreds was greater than the mean of the purebreds, the increase was considered to be the result of heterosis. Only the
Southdown x Dorset-Merino cross showed a significant increase. The
Hampshire x Dorset-Merino cross showed a decrease, as did the Shrop shire x Hampshire x Dorset-Merino cross. These workers concluded that there was little if any evidence of heterosis shown in the birth weights of the crossbred lambs. Their results indicated that the ewe may have a 106 greater influence on the birth weight of her offspring, than can be ac counted for by inheritance alone.
Heritab ility
Every characteristic is both hereditary and environmental. Genes cannot develop the characteristic unless they have the proper environ ment, and no amount of attention to the environment will cause the characteristic to develop if the necessary genes are not present. How ever, in some characteristics most of the differences between individuals are caused by differences in the genes they have, and only a few of the differences between individuals are caused by differences in the environ ments under which they developed. The difference between black and red coat color in cattle is an example of such a characteristic. On the other hand, there are characteristics in which most of the differences between individuals in a population are caused by differences in the environment, and only a small part of those differences between indivi duals are caused by differences in the genes they have. Yet it is certain that some individuals have genes which make them fatten more readily, grow more w o o ?l , or produce more milk than others.
Whether a characteristic is hereditary or environmental in degree depends on how much of the variation in that characteristic in a certain population is caused by differences in heredity, and how much is caused by differences in environment. Whether heredity or environment is the more important in causing variation in a characteristic in a particular population can be answered if the data are available. There is no
single answer for all the characteristics in one population, nor for the
same characteristic in all populations.
According to Lush (90), the actually observed variance is due in 107 part to differences in heredity which different individuals have and
in part to differences in environments under which different individuals
develop. "When the portion of the observed variance which is due to
differences in heredity is large, the character is said to be highly
hereditaryj when the portion is small the character is slightly heredi
tary or largely environmental. This definition includes as hereditary
the dominance and epistatic deviations, since they result from differences
in whole genotypes. Also included are the joint effects of heredity and
environment, which are thought to be small.
In the animal itself its genotype functions as a unit. This is
what is meant in the broad definition of hereditary. However, the gene,
not the whole genotype, is the unit of transmission from parent to off
spring. If it is assumed (Lush, 8?) that each gene substitution has
in every genotype exactly the same effect as the average effect which
it actually does have in that population, then by adding all these
average effects of the constituent genes an expected functioning or value
for each genotype is obtained. The variance among these expected values
constitutes the additively genetic variance in that population. This
additively genetic variance is a fraction of the actually observed
variance, and is what is referred to in the narrowest definition of
heritability. Discrepancies between the expected functioning and the
actual functioning of a genotype are called dominance deviations if they
are due to non-additive combination effects of allelic genes, or epistatic
deviations if the interacting genes are not allelic to each other (Lush,89).
The methods of estimating heritability depend on the degree to which
animals with similar genotypes resemble each other more than less close
ly related animals do. Dominance deviations generally lower the 108 correlation between relatives, but only with full sibs are they at all important. Only a sna.ll portion of the epistatic effects present in a population would contribute to the correlation between relatives when mating is nearly random. When a population consists of partially inbred lines unrelated to each other, a larger share of the epistatic effects are possessed in common by relatives. When heritability is estimated from the likeness of relatives, the estimate includes all of the variance due to additive genes but only a portion, usually less than half, of the epistatic variance and usually none but sometimes as much as a quarter of the variance caused by dominance deviations (Lush, 89)*
Methods of Estimating Heritability
Isogenic lines. A comparison of the variance within isogenic lines, and the variance in the population being analysed would show how much of the variance in the population is hereditary in the broad sense.
Except for identical twins, isogenic lines are not available. Identical twins have been used to determine the heritability of different charac ters, and this work will be discussed later.
Experiments with selection. If the amount is known by which the average of the parents exceeded the average of their generation, that amount can be divided into the amount by which the average of the off spring exceeded the average of the generation in which their selected parents were born, and an estimate of heritability obtained.
Correlations between relatives. This method has been used for a long time, but the necessity of appraising correctly the mating system used and of discounting the environmental correlations has caused geneticists to use it with caution in late years.
Relatives most useful. Parents and offspring are generally most 109 useful because it is expected that resemblance will be quite high if
the characteristic is highly hereditary. In this relationship, dominance deviations are not included, and it is less likely to have been affected by environmental contributions than is the resemblance between maternal sibs, (Lush,89).
Intrasire correlations or regression of offspring on dam. This has
proved to be the most popular method of estimating heritability in recent
years. It is based on the correlation or regression of offspring on dam
within groups of offspring by the same sire. The correlation and re
gression are interchangeable for this purpose if the dams were unselected.
Lush (8 9 ) stated that selection of the dams tends to lower the correla
tion coefficient but will not bias systematically the regression of
offspring on dam. However, the dependability (fiducial limits) of the
regression will be decreased. Selection of the offspring would reduce
the value of any estimate of heritability based on them. Generally
some selection will have been practiced among the parents; therefore,
Lush thought that regression was to be preferred to correlation.
The method of calculation is to obtain the intrasire regression
of daughter's record on dam's record. As a daughter receives only a
sample half of the inheritance her dam has, the regression of daughter
on dam must be doubled to estimate what fraction of the differences
between the records of the mates of a sire was due to differences in
the heredity of those mates, (Lush and Straus,96). Lush and Straus (96)
explained that this method is adequate for the average effects which
each gene had in the various combinations of genes with which it was
associated in a group of mates and daughters. When two or more genes
have, when together, an effect which is greater or less than the sum
of their average effects in that population, these differences between Ill
trlbuting much to the outward resemblance between daughter and dam*
Heritability of Characters in Dairy Cattle
Milk and butterfat yield, and butterfat percentage. Gowen (57) made the first attempt to measure heritability of milk yield, and butter fat percentage on the basis of the correlation between relatives (daugh- ters-dams, full sisters, and other combinations)* Approximately lit,OCX)
Jersey Register of Merit records, 36k to 366 days in length were used for the study* All records made at ages less than maturity were corrected to maturity. Gowen found that inheritance accounted for about 0.5 of the observed variation in milk yield, and 0*8 of the observed variation in butterfat percentage in single records. Environmental variations were thought to account for 10 per cent of the variation in milk yield and little of the variation in butterfat percentage. Gowen concluded that dominance, assortive mating, and environmental variation common to the cow herself accounted for the rest of the fluctuations in milk yields and butterfat percentages. According to Lush (90), if there were as much as 0.10 to 0.20 of environmental correlation between daughter and dam, Gowen*s figures were too high ty 0.20 to O.ljO*
Plum (109), using Iowa Cow Testing Association records and analyzing them by the method of analysis of variance, found differences of 26 per cent between cows. These differences were mostly hereditary. Lush and
Shultz (95) studied 2,385 daughter-darn comparisons, used to prove 355 sires in Iowa Dairy Herd Improvement Associations, for heritability of butterfat percentage and total butterfat production. The method used was correlation between daughter and dam within sire. About one-half of the variance in butterfat percentage was considered as hereditary in the simple additive manner, and the corresponding fraction for total 110
the actual and the expected effects are transmitted to the offspring only -when the -whole group of genes necessary for each such joint effect
is transmitted intact. Such differences are called dominance devia
tions if they are caused by two allelic genes, and epistatic or inter
action effects if they are caused by combinations of non-allelic genes.
Dominance deviations are not transmitted from parent to offspring, since
only one gene of the pair concerned can be transmitted in any one gamete.
Interactions due to the presence of two non-allelic genes would be trans
mitted to only one-fourth of the offspring (in a population mating at
random), and interactions requiring three such genes would be transmitted
to only one-eighth of the offspring. According to Lush and Straus (96), doubling the intrasire regression of daughter on dam gives an estimate of heritability which includes all of the additive effects of genes, none of the dominance deviations, and something less than half of the effects of the non-linear interactions of nonallelic genes.
According to Lush (89), computing the regression on an intrasire basis does much toward automatically discounting environmental contri butions and any peculiarities of the mating system. These difficulties are not solved; they are merely dodged by restricting the analysis to such variance as is found within groups of females which are mated to one sire. Whether differences between such groups of females are heredi tary or environmental in origin is not answered. The intrasire regression dodges most of the environmental correlations, because the daughters and mates of a sire are nearly always kept in the same herd. The effects of different management conditions in herds would be left in the differ ences between sires. The offspring of a sire are usually in a herd at abount the same time, and this keeps time trends in management from con- 112
fat production was about one-fourth. One-sixth of the variance in test
and one-third of that in total fat production was caused by management
or environment which was alike for all the cows in each herd but differed
from herd to herd#
Johansson and Hansson (71) studied heritability of butterfat yield and percentage in 12 high producing herds of Swedish Red and White cattle#
The data consisted of first lactations records of 1,1(89 daughter-dam
pairs# The average actual production was 322 pounds of butterfat, and
no corrections were made on the records# The repeatability within
herds was 0.38, 0.32, and 0,65 for milk yield, butterfat yield, and
butterfat percentage respectively. Heritability within herds was 0.36
for butterfat yield, and 0.68 for butterfat percentage.
Johansson (70) also reported on other studies of heritability.
The heritability estimate was based on the intrasire daughter-dam corre
lation using uncorrected first lactation records. The first study
involved 2,399 daughter-dam pairs of Swedish Red and White cattle.
Apparently these were good producing cattle; however, Johansson did not make this point clear* Heritability for butterfat yield was 0.39 within herds and 0.36 within herds and sires. The figures for butter fat percentage were 0.65 and 0.70, The second study was made on data from 1.052 daughter-dam pairs in 11 low producing herds of the same breed. The average butterfat yield was 226 pounds. The heritability estimate for butterfat yield within herds was 0.2i( and within herds and sires 0.31. The figures for butterfat percentage were 0.51 and 0.50.
Data for Johansson’s third study came from 25 herds of Swedish Polled cattle. The average for the first lactation was 201 pounds of butter fat. Heritability estimates of 0.1(6 for butterfat yield and 0.78 for 113
butterfat percentage within herds and sires were obtained. He thought
these estimates were too high, being based on a small number of data.
Lash et al. (93) determined the heritability of milk and butterfat
production from Iowa Dairy Herd Improvement Association data, used in
proving sires prior to January 1, 1937, and Holstein Herd Improvement
Registry data used in proving sires prior to October 1, 1938* They
found the hereditary differences between cows for the first lactation
in the Iowa data to be 28 and 33 per cent respectively for butterfat
and milk yields. In the Holstein data, the heritability of first and
second lactation butterfat records was 25 and 30 per cent respectively. The method used was that of doubling the intrasire regression of daughter
on dam.
Lush and Straus (96) analyzed the 305 day butterfat records of
2,15U daughter-dam comparisons that were used in proving 283 sires in Iowa Dairy Herd Improvement Associations during the period January 1,
1936, to December 31, 1939, for heritability of individual differences and magnitude of group differences. All records were corrected to a twice-a-day milking, mature equivalent basis. The problem was stated as follows*: "In the data currently being used for proving dairy bulls, how heritable are the differences between the butterfat reccrds of cows which are mated to the same bull?" The method of doubling the intrasire regression of daughter's record on dam's record was used in estimating heritability. The data consisted of at least five daughter-dam compari sons on each bull. The bulls were from the five dairy breeds, and two dual-purpose breeds, Shorthorn and Red Polled. The intrasire daughter- dam regressions varied from breed to breed, but the differences were not statistically significant. As the differences between breeds were 11U not significant the data were pooled, and considered as a homogenous
Intrasire population, Cn the basis of records in single lactations, the heritability of differences between cows mated to the same sire was
0.17U. When the data for the sires used only in one herd were analyzed separately, heritability was O.lliO instead of 0,17U, The small difference was not significant. The estimates of heritability were not signifi cantly higher in one breed than in another.
Bonnier (6) determined the per cent of variation in herd averages which was of hereditary origin. The data consisted of records made by cows of the Swedish Red and White breed during the period October 1,
1936, to September 30, 19U7, in the county of Halland, Sweden, Each herd contained at least 5 cows that had been on test 300 days during the year. The yearly records were corrected for age. Bonnier divided the herds into three groups on the basis of the herd averages (not corrected for age)r below 3,300 kg., between 3,300 and U,000 kg,, and above ij.,000 kg. Bonnier analyzed the data by analysis of variance. The mean square within herds increased from the lowest to highest producing herds. Bonnier thought that the cows in the herds with the lowest averages had not been fed enough to express their abilities. He there fore used the mean square of the highest herds for within herds. Bonnier concluded that not more than 16 per cent of the variation in the herd averages was of hereditary origin,
Tyler and Hyatt (1U8) investigated the heritability of milk and butterfat production, and butterfat percentage in Ayrshire cattle. Their data consisted of production records of 6,888 daughters and mates of 37h
Ayrshire sires. All milk and butterfat records were converted to a twice-a-day milking, 305 day mature equivalent basis. Twice the intrasire 135 regression of daughter's production on dam's production was used to estimate the heritability of differences in single unselected records of milk and butterfat and the percentage of butterfat* The estimates were
31, 28, and 55 per cent respectively. The results indicated that butter fat percentage was about twice as heritable as milk and butterfat produc tion* About 20 per cent of the heredity that influenced milk and butter fat production also affected the percentage of butterfat in the milk*
They found that 85 per cent of the animal's genotype that influenced milk production also influenced the production of butterfat*
Beardsley et al, (U) investigated the heritability of butterfat production in 3,307 daughter-dam comparisons, used in proving 1?6 sires of the Guernsey, Holstein and Jersey breeds, in Dairy Herd Improvement
Associations* Each sire had a minimum of five daughter-dam comparisons in each of two or more herds* The pooling of the variances of the three breeds was found to be justified, A multiple regression of daughters' butterfat production on dams' butterfat production within breeds, sires and herds was computed for the purpose of estimating the curve of heritability. As a single coefficient cannot describe a curvi linear regression, heritability could not be estimated by doubling a single regression coefficient* Average linear regression coefficients were estimated at varying levels of butterfat production. These co efficients were doubled to obtain estimates of heritability at various production levels* The estimate of the average heritability of butterfat production was 27*ij per cent. Curvilinear regression of daughter on dam within breeds, within sires and within herds, accounted for a larger portion of the daughter variance than did linear regression* The difference 116 was not quite statistically significant at the 5 per cent level of probability. However, these workers maintained that this was not evidence that true regression was necessarily linear, for the curvilinear regres sion fitted the data more closely and they thought it was the most proba ble answer* The values for heritability on the basis of curvilinear regression decreased as the level of butterfat production increased*
The percentages of heritability when the dams averaged 250, 350, U50, and
550 pounds of butterfat were U5.0, 31.U, 23*0, and 17*0 per cent respec tively* Most studies on the heritability of dairy records have been made on groups of daughter-dam comparisons from approximately twelve to many herds* In 1950, Laben and Herman (82) reported on a study of heritabi lity of dairy records in the University of Missouri Holstein herd. The records were made in the period from 1902 to 1950. Thirty-four sires were represented by 270 daughter-dam comparisons. The records were standardized to a twice-a-day milking, 305 day mature equivalent basis*
The method used to estimate heritability was that of doubling the intra sire daughter-dam regression* The estimates of the heritability of single records were 0.36, 0*29, and 0.5U for milk yield, butterfat yield, and butterfat percentage respectively,
Touchberry (11*5) determined the heritability of milk and butterfat production in the Iowa State College Holstein herd. The data consisted of production records of 187 daughters by 22 different sires and from.
180 dams. The production records used were those started nearest the third birthday, and were on a twice-a-day milking, 2l*3 day mature equivalent basis. The method used was to obtain intrasire daughter-dam correlations and double them. Estimates of 0.25, and 0.35 were obtained 117 for the heritability of milk, and butterfat production respectively.
Larson et al. (8U) studied the use of butterfat produced per day of life as a criterion for selection in dairy cattle. The data came from two herds, and heritabilities were computed by doubling the intra- sire regressions of daughter on dam. The estimate of heritability of first lactation butterfat production was 0.30. Heritability of produc tion per day life at any of the ages studied from thirty-six to eighty- four months was not established; nor was age at first calving indicated to be heritable.
Bonnier et al. (7) determined the variance due to heredity in dairy records using identical twins. While the ancestry of most of the animals was not known it was assumed that they were of the Swedish Red and White breed. In the first experiment the averages were based on six pairs in the first two lactations, and on five pairs in the third lactation. The production during the first 36 weeks of a lactation was used as the record of an animal. One animal of each pair had been raised on a low level of feeding, and the other on a high level of feeding.
This method of treatment showed up in the production, as the animals that had been raised on the low level of feeding produced less during the first two lactations than the animals that had been raised on the high level of feeding. Production in the third lactation was similar for both groups. Milk yield was expressed on the basis of ton calories
(T.C.). In milk yield the part of the variance which was ascribed to heredity in the first lactation was 21 per cent, but increased to 88 and 90 per cent in the second and third lactations as the animals approached maturity. The effect of the interaction between heredity and environment was highest in the first lactation, then dropped to 118
8 and 10 per cent for the second and third lactations* The part of
the variance in butterfat percentage -which was attributed to heredity was 81, 88, and 87 per cent in the first, second, and third lactations respectively.
In the second experiment reported by Bonnier et al. (7), seven pairs of identical twins were used. The difference between the feeding
levels of the low and high animals when they were being raised was less
than in the experiment reported on page 117. The data used consisted
of the first 36 weeks production of the first lactation. The variance
in milk production attributed to heredity was 70 per cent, and that for butterfat percentage, 83 per cent. The authors concluded that heredity in importance, usually, outweighs the effects of differences in feeding intensity, even when those differences are large.
Solids not fat. In the first experiment discussed on page 117,
Bonnier et al. (7 ), found that the variance due to heredity in the percentage of protein in the milk was 88, 93, and 89 per cent for the first, second, and third lactations respectively. The variance due to heredity in the percentage of lactose was 90, h3, and 70 per cent. In the second experiment the variance in protein due to heredity was 82 per cent and in lactose 33 per cent.
Birth weight. Tyler et al. (II4.7 ) estimated the heritability of birth weight from data on Holstein calves. Three correlation methods and intrasire regression of offspring on dam were used, the average estimate being 0.60 with a 95 per cent fiducial range of 0.50 to 0.70.
Type and body size. The heritability of official -type ratings in Ayrshire cattle was investigated by tyler and ^yatt (1U9). The data used 1 1 9
■were the type ratings o.f Ayrshire cows classified between March, 19h2, and May, 19U6. An estimate of heritability of type was obtained from the ratings of 3,738 cows sired by 368 bulls. The average correlation between daughters of the same sire was obtained and it amounted to 0 .1 2 .
Taking into account the probable genetic relationship of the paternal
sisters an estimate of 0.U0 was obtained for heritability. There were
1,601 cows whose dams were classified at the same time. The regression
of daughter’s rating on dam’s rating within sires was obtained and
doubled. This gave an estimate of 0.28 for heritability. The two esti
mates were combined, the average figure being 0 *3 0 , and the 95 per cent
fiducial limits were 0.19 and 0.U2. The chances are 19 out of 20 that
the real heritability of type ratings in these data was between the
two limits.
tyler ejj al. (1 5 0 ) determined the heritability of body size (height
at withers, circumference of shin bone, heart girth, width of hips)
of Holstein cattle at the age of six months, eighteen months, and maturity^ and of body size (weight and height at withers) of Ayrshire
cattle at six, twelve, eighteen, and thirty-six months of age. The
intrasire regression of daughter's measurements 011 dam’s measurements,
and paternal half-sib correlations were used to estimate heritability.
For the Holsteins, 15 per cent of the variation in body size at six
months, 3 5 to 65 per cent at eighteen months, and between 3 0 to 60
per cent at maturity were caused by hereditary differences between in
dividuals. For the Ayrshires the heritability estimates were 20 to 35
per cent at six months, 30 to 6 0 per cent at twelve months, 20 to lj.0
per cent at eighteen months, and 15 to 3 0 per cent at thirty—six months.
These workers concluded that selections for body size in dairy cattle 120
could be effective in changing body size of subsequent generations.
Touchberry (lh5) found that in a herd of Holstein cattle the six
measurements of size; weight, wither height, chest depth, body length,
heart girth, and paunch girth had heritabilities of 0.37* 0*73* 0.80,
0,58, 0.61, and 0.27 respectively.
Reproductive efficiency. Dunbar and Henderson (36) used two measures
of fertility, non—returns to first service and calving interval in deter mining heritability of fertility. These workers used an estimation pro
cedure which, thqy stated, yields unbiased estimates of components of variance in non-orthogonal data. Estimates were obtained of the variance due to additive genetic differences among sires. Sire variance was almost zero in both studies, and the heritability of fertility was
estimated to be near zero.
Legates (85) investigated the heritability of services per con ception and calving interval using data from 12 North Carolina State owned herds. The intrasire regressions expressed on single observations for the dams were 0.013 for services per conception, and — 0.018 for calving interval. Doubling the regression coefficient for services per conception gave a heritability value of 0,026. Legates concluded that the evidence indicated little genetic variability in the two measures of reproductive efficiency studied, and that application of genetic principles in selection for the two measures studied would not be of much value.
The results obtained by Wilcox et al. (155) from a study of the breeding efficiency of cows in the Overbrook Dairy Herd are different from most studies. These cattle were Holsteins and the measure used was calving interval. Included in the study were all animals that 121
stayed in the herd as long as they were economical milk producers*
Animals which left the herd because of disease* accidents or foreign
bodies were excluded. The estimate of heritability of breeding effi
ciency was 32 per cent.
Gestation length. Stallcup et al. (llt-O) in a study of the gesta
tion lengths of calves born in the University of Arkansas herd* ob
tained estimates of the heritability of gestation length for Holsteins
from zero to 0.20, and 0.22 to 0.30 for Jerseys, depending on the method
of calculation.
Rollins et al. (125) analyzed the gestation lengths of calves born
in the inbred Jersey herd at the University of California. The heritabi
lity estimate obtained was 30 per cent.
Disease. Using data from 27 herds of cattle in New Zealand* Lush (92)
found that the average intraherd regression of daughter on dam was 0.19
for the incidence of mastitis. Doubling this figure gave an estimate
of heritability of individual differences in susceptibility to mastitis
of 0.38, However, the 95 per cent confidence interval for this figure
ranged from 0.06 to 0.70. Lush concluded that the evidence indicated
heredity plays some part in whether a cow develops mastitis or not* but
that the data were too few to say how much with any accuracy.
Casida and Chapman (16) determined the heritability of the occurrence
of cystic ovaries sometime during life and found that it was 0.J+3. The data came from one Holstein herd. The weighted mean of the percentages
of the daughters from cystic cows that were cystic was 31*0, and for
those daughters from non-cystic cows the weighted mean was 9.U. Twice
the difference between these two values* U3.2 per cent* gave an estimate 122 of the heritability of the occurrence of cystic ovaries, in a popula tion in which the dams and daughters had spent the same number of service periods in the herd. EXPERIMENTAL
Data
Source of Data
The data used in this dissertation were obtained from records in
the Dairy Department of the Clemson Agricultural College, Clemson,
South Carolina. These data consist of measurements of different
characteristics of purebred and two-breed crossbred dairy calves, and
cows as follows:
1. Birth weights of male and female calves
2. Gestation lengths of male and female calves
3. Body weights of female calves at 90, 1J>0, and 180 days of age
U» Circumference of fore chest, or heart girth measurements of
female calves at 90, 150, and 180 days of age
5* Mammary gland grades of female calves at five months of age
6* Body weights at first freshening
It has been a routine practice for many years to weigh each calf,
and its mother as soon as practical after birth of the calf; however,
the weighing has been curtailed at times because of a lack of labor*
The gestation lengths were calculated from data on the breeding
record of the mother of a calf. Data on the breeding record of a
cow consisted of date of service, the bull used, calving date, number of the calf, and weight of the calf and mother. Each calf was assigned a number within its breed if a purebred, or if a cross
bred it was given a crossbred number.
The body weights, heart girth measurements, and mammary gland measurements of calves 90 to 180 days of age were obtained by the
123 12k writer, and Professor C. C. Brannon beginning in July, 19M3.
The first two-breed crossbred calf was born on March 15, 1937 > and the remainder of the crossbred calves on which data were included were bom between that date, and September 30, 1956. A two-breed calf is produced by mating animals of two pure breeds. The purebred calves on which data were included were born between December 1,
1936, and September 30, 1956, except that it was necessary to include data from a few calves born after the latter date, in order to determine the transmitting ability of three bulls for certain characters. The date December 1, 1936, was the birth date of the first purebred calf sired by a bull that also sired a crossbred. The dams of these purebred and crossbred calves were, of course, born at least two years earlier. Data on all purebred progeny of the sires of cross bred calves were used. In addition data on calves sired by all
Guernsey, and Holstein bulls in service since 19i|0 were included in order to have larger numbers for obtaining heritability estimates.
Environmental Conditions 'Which Have Prevailed
Among the characters studied, those which could be affected most by herd environment would be body weights, and measurements at
90, 150, and 180 days, mammary gland grade, and weight at first freshening. In general the management practices have been consistent over a period of years, but feeding practices have varied. The female calves were removed from their dams at two to four days of age, and taken to a calf bam. They were given whole or skimmilk until six to eight weeks of age. During this period they were also fed grain, hay, and had water available. After the calves were weaned from milk the 126 analyzing all of these data. By this method the crossbred and purebred progeny of a sire were compared, taking into consideration the merit of the dams. The data on the maternal half-sib(s) to a crossbred were combined with the data on the dam to obtain a "genetic" value for the dam. Adjustments were then made for differences in the dams of the crossbred and purebred progeny of a sire. Taking an illustration, if groups of Holstein and Guernsey cows of equal merit were mated to a Holstein bull, the two groups of daughters would be expected to be similar. This was not true for some of the characters studied because of maternal effects, and these effects were taken into consideration.
Equation for estimating heterosis. The equation for estimating heterosis is
H = (A-B) - (C-D) (1) 2 where
A = mean of one or more crossbred daughters of a sire,
B = mean of purebred progeny of above sire,
C = mean of estimated genetic value(s) of one or more dams
of crossbred daughters sired by above bull, and
D = mean of dams of the purebred daughters of the above sire.
The means for A, B, and D are considered to be estimates of genetic values. The use of the above equation to obtain H amounts to com paring the crossbreds to the parental mean where
parental mean (2 )
S = genetic value of the sire and would be estimated (3)
as 2 B - D. 12S amounts of grain and hay were increased. The calves were kept in the calf barn until three to five months of age, at which time they were moved to another barn or turned into a lot where they had access to a shelter which opened to the south. The calves were kept in lots near the main barn until eight months of age. At this time they were moved to another farm where they were raised, bred, and kept until a few weeks before freshening. Sick calves were always treated. White scours and pneumonia were the diseases which caused the most trouble.
Objective and Method Used in Analysing Data
The objective in analyzing these data was to determine if the two-breed crossbreds showed heterosis for the characters previously mentioned, when compared to their purebred relatives.
In a study of possible methods to be used in analyzing these data, it was clear that the best method of analysis would be one whereby the information on the dam, paternal, and maternal half-sibs could be utilized in one comparison with the crossbreds. The dam, paternal, and maternal half-sibs were all purebreds. The important problem concerned the use of data on the maternal half-sibs to the best advantage. In most cases there were usually five or more purebred paternal half-sibs to a two-breed crossbred, because an attempt had been made to prove the sires for mill: production on at least ten daughter-darn pairs. The number of maternal half-sibs of the two-breed crossbreds varied from none to nine.
The writer is indebted to Dr. R. S. Comstock, Genetic
Statistician, formerly of North Carolina State College, now at the
University of Minnesota, for outlining the method which was used in 12?
Substituting 2 B - D for S in the parental mean,
(C + 2 B - D)_ „ . (C - D) ------B +------(10 2 2
Then the difference between a crossbred or crossbreds and the parental mean is
(A-B) - (C-D) (5) 2
which is the quantity H in (l).
Null hypothesis. The null hypothesis was that there was only additive gene action and no heterosis. On a stict additive basis the difference between the daughters should be half the difference between the dams. If disproved there would be some heterosis, and the gene action woiild be thought to be something in addition to
additive gene action. The H value was calculated for each crossbred of a certain type of cross. Then an analysis of variance was run
on the II values to test for sire differences. If the variation in
H values among sires was significant, the t-tsst which was used to
determine the significance of the mean of the H values was run on the basis of sires. If the variation in H values among sires was
not significant, the t-test was run on the basis of individuals.
Calculation of C. The genetic value for the dam of each cross
bred was estimated separately. The darn’s record for the character
being studied provided one estimate of her genetic value, and if she
had no purebred progeny of the same sex as the crossbreds being evaluat
ed, that record became her genetic value. If the dam had purebred
progeny of the same sex as the crossbreds being evaluated, an estimate 128 of bar genetic value was obtained on the basis of one or more progeny by each different sire* The genetic value of the dam or C was
obtained as a weighted average of these estimates, where the weights
were inversely proportional to the variances of the estimates.
The equation for the calculation of G for a dam with no progeny
xs
Vo C = — - (6 ) 1__
Vo
which amounts to her actual record for the character.
The equation for the calculation of C where there is one or more
progeny is
1 CQ + 1 C-l + 1 C2 +
Vo V 1 V 2 C = ------(7) 1 + 1+1 Vo V;, V 2
where
CQ = estimate provided by dam's own record,
= estimate based on record(s) of purebred progeny by sire 1 ,
C2 = estimate based on record(s) of purebred progeny by sire 2 ,
to Cn = estimate based on record(s) of purebred progeny of
additional sires,
V0 — variance of CQ ,
Vl = variance of Cq_,
Vg = variance of Cgj and
VqJ to V n = variances of C, j to C_. n 129
Substituting equation (7) for C in equation (1) gives
1 c 0 1 cx 1 c 2 , - 4. - . - ^ ^ Vo V2
1 1 — + — + 1 + Vo vx V2 - D H = (A-B) - (8)
Calculation of _c1 . cx is the estimate of the dam's genetic value from her purebred progeny by sire 1 .
Let S^l — the sire of one or more maternal half-sibs to a crossbred,
S2 = the sire of one or more other purebred maternal half-sibs
to the same crossbred,
M-^ = mean for one or more maternal half-sib(s) sired by
F-l = mean of all "other" purebred progeny sired by excluding
the one or more daughters that make up M-j_, and
G^_ — mean of the dams of F-^.
There could also be Mgj F2 * anc^ ^2 ^ I ^ I h E maternal half-sibs by Sg> and so on for maternal half-sibs by any other sire or sires.
The calculations for obtaining C2 &nd are the same as those to
obtain C 1 where C1 = 2Mi “ s! (9)
and Si = 2Fl - G;l (1 0 )
therefore °1 = 2ml " 2F1 + V (11 ) If = F-^> v/as taken as equal to G^. If was less than
F-^, C-^ was taken as less than G-, , and the difference was twice the
difference between and F^. Conversely if was greater than F^,
C-jl was taken as greater than , and the difference was twice the 130
difference between and F-^.
Equations for calculating variances of estimates of the genetic value of the dam* The genetic value (c) of the dam was obtained as a weighted average of the estimates of her genetic value, and the weights were inversely proportional to the variances of the estimates. The equations for calculating the variances were derived by Comstock (28).
Let V = variance,
VQ = variance of 0o,
V-^ = variance of C-^,
Vg = variance of C2 >
to = variance of C3 to Cn ,
h = heritability, which is the fraction of the observed
variance which is due to additive genes,
x = the number of maternal half-sibs to a crossbred by the
same sire, and
y ~ the number of other purebred progeny of a sire whose dams
have records, excluding the maternal half-sib(s) for which
the variance is being calculated and whose dam has a cross
bred progeny.
The equation for calculating the variance of the estimate for
Cc , or the dam is
V Q = (1-h) V. (1 2 )
The equation for calculating the variance of the estimate for
the first purebred progeny (C^) is
(13) 1 3 1
Equation (13) was also used to calculate the variance of the estimate for additional purebred progeny, Cgj to of the dam*
Analyses of Data and Results
Birth Weights Birth weights were available on at least five male, and five female two-breed crossbreds and their dams for the crosses shown below. Birth weights were also available for male, and female calves of each of the pure breeds* The breed of the sire is given first, and the breed of the dam is given second reading from left to right.
This method will be used to designate the breed of the sire, and dam of a crossbred throughout the dissertation*
Guernsey x Holstein
Holstein x Guernsey-
Brown Swiss x Holstein
Brown Swiss x Guernsey
Five Holstein x Jersey females had been born up to September 30,
1956, "but only four pairs were available as there was no birth weight
on one dam*
In most cases letters will be used to indicate the breeds of
animals in a cross as followss
G = Guernsey
H = Holstein
J = Jersey
S = Brown Swiss
The birth weight, and gestation data were taken from the herd 132 books at the same time* and the calves were listed according to sires*
The first requirement was that the calf be bred and born at Clemson*
In two breeds, Guernsey and Brown Swiss, some of the animals had been born at Clemson but bred in other herds; others were bred and born in other herds.
Other requirements were that the calf be normal in appearance, live after birth, and that there be no question about the sire of the calf or the date of service from which the calf was born. A few calves were excluded because the sirs could not be identified, or the gestation length could not be established because the calf was born between the due dates for two services to the same bull. This procedure eliminated the birth weights of a few calves in the latter group, however they were used as dams in the birth weight study*
Since blood typing has been available most cases of doubtful parentage have been solved by using blood types; if not, the animal was sold.
Gestation lengths were available on all calves listed; however, the birth weight or weight of the dam were not always obtained, so for each group of calves there xrere usually less data for birth weights than for gestation length, height at birth or length of the gestation period was not used as a criterion for including or excluding calves.
Calves born twin to another calf were not used as c-alves, or as
dams if they were females and produced progeny. Calves, the result of sire to daughter, son to dam, or full brother to full sister matings were not used as calves but were used as dams if they were
females and produced progeny.
Before the analysis of birth weights was started, consideration was given to factors for which the data should be adjusted. Tyler et al. (lh7), Nelson and Lush (102), Touchberry and Tabler
(lil6 ) and Martin (97) all found that purebred and crossbred male
calves of dairy, and dual-purpose breeds were heavier than female
calves at birth. All of these workers found that age of the dam,
calving sequence, size (heart girth), or weight of the dam had an
effect on the weight of the calf, in that older, heavier cows tend
to give birth to heavier calves. Tyler et al. (llj.7) found that
calving sequence was slightly more important as a source of variation
in birth weight, than size of the darn as determined by heart girth measurements. Touchberry and Tabler (ll|6 ) reported that Guernsey,
Holstein, and crossbred calves of these two breeds increased 0.£
pound for each 100 pounds increase in the weight of the dam.
Tyler et al. (l!;7) analyzed the birth weights of Holstein calves,
and found no significant differences between years or seasons.
Davis (31) studied the influence of the month of birth on birth
weights of Holstein calves born during a twenty-one year period, and
found that it was not significant.
Regression of birth weight of calf on weight of dam at calving.
It was decided to adjust the birth weights of the calves for the
weights of the dams at calving. In order to obtain values for making
the adjustments, regression coefficients for birth weight on weight of
dam at calving were calculated for each group of calves by sex, and
breed if purebred, or breed combination if crossbred. The birth
weights on all calves whose dams were weighed at calving were used.
All of these calves were bred and born at Clemson.
The linear regression coefficients were calculated according to 131;
the method given by Snedecor (136) with birth weight as Y or dependent variable, and weight of the dam as X or independent variable. The regression coefficients for male and female calves of the Holstein,
Guernsey, and Brown Swiss breeds, and the G x H, H x G, SxH, and
S x G crossbreds are given in Table 1. In addition the number of pairs of calves and dams in each group, average weight of the calves with standard deviation, average weight of the dams with standard deviation, the standard error of the regresssion coefficient, degrees of freedom, and the t-value are given. The regression coefficients for the purebred male, and female calves weic- all significant (P<0.01) whereas those for the crossbreds varied a .great deal presumably because of small numbers. It will be noted that two coefficients were
calculated for the S x G males. According to the records one calf weighing ?6 pounds was from a dam that weighed 620 pounds. This was
the heaviest weight for male calves of this cross, and the dam was the lightest cow of all the dams. When this pair was included the
regression coefficient was negative, when it was excluded the
coefficient was positive.
The birth weights of the male and female calves of the Brown
Swiss, Guernsey and Holstein breeds were adjusted using the equation
given below from Snedecor (136).
Adjusted Y = X - bx
where
Y = actual weight of the calf
b = regression coefficient
x = deviation of the weight of the dam in pounds from the
weight of dam to which the calf weight was being adjusted. Table 1
Regression of Birth Weight of Calf on Weight of Dam (Pound of Calf on Pound of Cow)
S. S. of Degrees Average Weight Average Weight Regression Regression of Breed Sex Pairs of Dams of Calves Coefficient Coefficient Freedom t-value
(no.) (It.) (lb.) (no.)
Holstein Female £68 1,259 + I82a 91.5 + 11.3a 0.0232 0.0021*2 566 9.587 •K* Holstein Male 60£ 1,253 + 177 96.9 + 12.2 0.0317 0.00250 603 12.680 ■K* Guernsey Female 1*50 996 + 11*9 70 .0 + 10.1 0.0310 0.00266 1*1*8 10.839 ** Guernsey Male 1*80 995 + lid* 75.0 + 1 0 .6 0.021*2 0.00319 1*78 7.586 B. Swiss Female 121 1,293 + 185 9lt.0 + 13.3 0.0276 0.00609 119 1**532 ■ft* B. Swiss Male 11*7 1,295 + 176 102.0 + 13.2 0.0301 0.00569 11*5 5.290 G x H Female 31 1,193 + 127 86.9 + 9.8 0.0082 0.011*21 29 0.577 G x H Male 30 1,259 + 155 93.3 + 10.1 0.0189 0.01179 28 1.603 H x G Female 27 1,011* + 106 83.7 + 9.6 0.0255 0.01737 25 1.1*68 H x G Male 25 1,01*1 + 107 81*.8 + 8.3 O.Ok39 0.01337 23 3.283 S x H Female 12 1,079 + 151* 86.6 + 10.0 0.0208 0.0191*3 10 1.070 S x H Male 23 1,212 + 170 101.3 + 12.0 0.01*98 0.01093 21 1**556 S x G Female 9 953 + 131 83.2 + 9.e 0.01*80 0.02152 7 2.230 S x G Male 9 961 + 200 88.3 + 7.1; - 0.0031* 0.01388 7 - 0.21*5 S x G Male 8 i,ool* + 165 87.1;+ 7.3 0.0098 0.01759 6 0.557
a Standard Deviation. ■a* Significant at 1 per cent level (P<0.01). 136
The adjustments for the different breeds were as follows:
Brown Swiss
1* Weights of female calves adjusted to 1293 pound dams using 0.0276
2. Weights of male calves adjusted to 1293 pound dams using 0.0301
Guernsey
1. Weights of female calves adjusted to 996 pound dams using 0.0310
2. Weights of male calves adjusted to 996 pound dams using 0.02U2
Holstein
1. Weights of female calves adjusted to 12^9 pound dams using 0.0232
2. Weights of male calves adjusted to 1239 pound dams using 0.0317
To obtain heritability estimates from the weights of the male calves, and to make comparisons between purebred and crossbred males by the same sire it was necessary to put the dams of males on a male basis. The amount to add to the dams adjusted birth weight was found by obtaining the difference between the averages of the adjusted male, and female -weights of a breed. The averages of the adjusted male and female weights, and the differences are shown for the Brown Swiss,
Guernsey and Holstein breeds in Table 2. 137
Table 2
Averages of Adjusted Male and Female Weights and Difference by Breed
Male Female Breed No. Average Weight No. Average Weight Difference
(lb.) (lb.) (lb.)
Brown Swiss 12*7 101.93 + 12.07a 121 93.96 + 12.29 7.97 Guernsey 1*80 75*06 + 10.05 1*50 70.03 + 9.01 5.03 Holstein 605 97.05 + 10.88 568 91.53 + 10.1+6 5.52
a Standard deviation.
The number of pounds added to the adjusted birth weights of dams
of male calves was 7.97 pounds for Brown Swiss, 5*03 pounds for
Guernseys, and 5*52 pounds for Holsteins.
Estimates of heritability of birth weight. In order to calculate
the variances of estimates of the genetic value of a dam of a crossbred by equations (1 2 ), and (13) estimates of the heritability of birth
weight were neededo The method used was that of intrasire regression
of progeny on the dam, then the regression coefficient was doubled
to obtain the estimate of heritability. This method was described by Lush (89), and discussed in the Review of Literature.
Eirth weights which had been adjusted for the weight of dam at
calving were used for the dams and their progeny. In addition the
weights of dams of male calves were adjusted to a male basis. The
adjusted birth weights of calves and their dams that were bred, and
born at Clemson were used for all the analyses to be presented.
The statistics obtained from the intrasire regression of progeny
on dam analysis are given in Table 3* Table 3
Average Weights, Intrasire Regression Coefficients and Heritability Estimates for Birth Weight by Sex and Breed
No. Average Average S. E. of Degrees of Weight Weight Regression Regression of Herit. Breed Sex Pairs Sires Progeny Dams Coefficient Coefficient Freedom t -Value Estimate
(no.) (lb.) (lb.) (no.)
B. Swiss Male 81* 7 101.21 lOii.18 0.2726 0.11*75 75 1.81*8 0.51*5
B. Swiss Female 78 6 93.35 95.58 0.391*5 0.1515 70 2 .601* # 0.789
Guernsey Male 351* 28 7k.90 73.56 0.21k9 0.056? 321* 3.790 ** 0.1*30
Guernsey Female 3!j0 30 70.19 68.93 0.1098 0.01*81* 318 2.268 * 0.220
Holstein Male 568 19 97.08 97 .Oli 0.0782 0.01*96 51*7 1.577 0,156
Holstein Female 526 20 91.71* 91.03 0.0997 0.01*79 501* 2.081 * 0.199
* Significant at 5 per cent level (P<0.05). Significant at 1 per cent level (P<0.01). 139
A n a l y s i s Qf birth weights of G x H females* Thirty-nine females of this cross were born before September 30, 1956* Birth weight data were available on 28 of them, and their dams. Of the remaining eleven, two were born dead, two were twins, three were from dams that had not been weighed at birth, three were from dams that were not weighed when the crossbred calves were born, and the calving weight for the dam of one calf was obviously too high.
The birth weights of the 28 crossbreds, and their dams were adjusted to 12^9 pound dams using the regression coefficient 0 ,0 2 3 2 ,
The basic data are given in Appendix Table 1, The birth weight and adjusted birth weight are given for each crossbred and her dam, also given is the adjusted birth weight for each maternal sister, and the average of the adjusted birth weights for the other daughters of the sire of each maternal sister, with the average of the adjusted birth weights of their dams. The code name of the sire of one or more crossbreds is given on the left of the page.
The adjusted birth weights of the crossbreds in Appendix
Table 1, are ready to use in calculating H values. If the dam had no daughters her adjusted birth weight became her genetic value, because Equation (6 ) does not change it. If the dam had purebred daughters, (C^) to (C ) were calculated using Equation (11). These are estimates of the dam's genetic value based on her transmitting ability, and the transmitting ability of the sire or sires of the maternal sisters. Next the variances of the estimates were calculated, using Equation (12) to obtain the variance for the dam or (0o), and Equation (13) to obtain the variances for the estimates for the daughters (C]_) to (Cn) . The final step iho calculation of genetic value or (C) for the dam using Equation (7)*
All data needed to obtain an H value for each crossbred using
Equation (l) are given in Table iu These data are the adjusted birth
■weight (A) of the crossbred, the number and average of the adjusted birth weights (B) of her sire's daughters, her dam's genetic value
(C)* and the average of the adjusted birth weights of the dams of the paternal sisters (D). The calculated K values are also given* The code name of the sire of one or more crossbred daughters is given on the left side of the page. The steps in calculating the II values were enumerated in order that the reader would be familiar with them.
They will not be repeated.
Table I4
Adjusted Birth Weights of 0 x H Crossbred Females (A), Number and Average of Adjusted Birth Weights of the Paternal Sisters (B), Genetic Values for the Dams of the Crossbreds (c), Average Adjusted Weight of the Dams of the paternal Sisters (D), and Calculated H values
Herd No. No. Crossbred Paternal Sire Daughter A Sisters B C DH
Holliston 1 90.28 k 6 1.80 110.51i 58.75 2.58 3 93.57 k 61.80 102.10 58.75 10.09
Majesty 7 82 J46 11 6$.0k 90.65 6 2 . 6k 3.k 2
Knight 18 107.60 15 76 .U7 93.68 6U.75 16.67
Hollllier k3 8 6 .I4.6 12 65.73 82.65 6U.63 11.72
Hollibright 52 7U.5U 29 70.31 83.88 67.08 - U.17
Honor 100 101.08 ko 71.71 92.83 6 7.61 1 6 . 7 6 1U0 80.53 h0 71.71 90.6U 67 .61 - 2.70 151 7U.63 ko 71.71 83.67 6 7.61 - 5.11 158 1 0 1 .ko ko 71.71 83.16 67.61 21.91 170 101.86 ko 71.71 92. U6 67.61 17.73 183 85.70 ko 71.71 82.78 67.61 6 J4.I Table h (continued)
Herd No • No. Crossbred Paternal Sire Daughter A Sisters B c D H
Honor 189 9 6 J46 ho 71.71 70.38 67.61 23.37 196 73.66 ho 71.71 82.02 67.61 - 5.25 200 8U .02 h0 71.71 96.83 67.61 - 2.30
Trophy- l5h 93.82 13 72.8h 95 .1+9 71.92 9.20 156 8h.3h 13 72.8h 78.9h 71.92 7 .99 180 102.93 13 72.8h 85.98 71.92 23.06 19h 95.99 13 72.8h 102.80 71.92 7.71 198 82.90 13 72.8h 76 .h8 71.92 7.78 2h5 88.52 13 7 2 .8h 79.30 71.92 11.99
Main Stay I8h 83.20 18 69.52 103.16 6 7 . 2h - h.28 185 7h.21 18 69.52 100.69 67.2h -12.03 199 101.31+ 18 69.52 87.15 6 7 .2h 21.86 271 70.96 18 69.52 79.9h 6 7 .2h - h.91
Fame 232 95.83 11 67.62 95.22 73.09 17.15 251 95.53 11 67.62 102.09 73.09 13 .hi
Foremost 270 82.09 10 73.16 90.hh 69.07 - 1.75
28 individuals, 10 sires.
Sum of positive - negative H values in Table h = 208.31
Sum of squares of all H values = h, 367.5917
Minus correction for sum of squares ^ = Ij5h9*7520
Corrected surn of squares = 2,817.8397
Mean of H = 208.31 +28 = 7-hh
Before the t-test was applied to the mean of H, an analysis of variance was run on the H values. This was done to determine whether the t-test should be run on the basis of individuals or sires. The calculations were made as described by Snedecor (136) for subsamples, with different numbers of individuals, and the statistics are given 1U2
in the first line of Table In order to keep from having many-
small tables, the statistics from the analyses of variance on all
of the crossbred groups for which birth weight data were available are given in Table 5•
The value of F was not significant, therefore the t-test was run
on the basis of individuals.
Mean square of H values = 2,817*8397 * 27 = 10ij.*362Ui.
Variance of mean of H = 10iu36hk t 28 = 3*7273
t . i S L - ^ - 3.855 _ v 3.7273 1.98
For 27 degrees of freedom the t-value was significant at the
1 per cent level.
Analysis of birth weights of II x G females. Thirty-one H x G
females had been born up to September 30, 1996. Two of them were from
a dam that had been born a twin, while four were twins, (two pairs)•
Data were available on the remaining 29 calves, and these data were
used in the analysis.
The birth weights of the II x G females were adjusted to 996
pound dams, using 0.0310 which was the procedure followed in adjusting
the birth weights of purebred Guernsey females. The basic data are
given in Appendix Table 2. The data used in calculating H values, and
the calculated H values are given in Table 6 . Table 5
Analyses of Variance of H Values Calculated from Birth Weight Data for Groups of Crossbreds
Total Variation Variation Between Sires Variation Within Sires Degrees Sum Degrees Sum Degrees Sum Value Crossbred of of of of Mean of of Mean of Combination Sex Freedom Squares Freedom Squares Square Freedom Squares Square F
G x H Female 27 2,617.8k 9 766.80 85.20 18 2,051.01* 113.95 0.75 H x G Female 21* 2,028.39 8 768.82 96.10 16 1,259.57 78.72 1.22 S X H Female 8 1,503.01 5 1,202.59 21*0.52 3 300.1*2 100.11* 2.1*0 S x G Female 5 66.16 3 31.71 10.57 2 31* .1*5 17.22 0.61 G x H Male 27 3,336.37 10 l,k98.38 11*9.81* 17 1,837.99 108.12 1.38 K x G Male 22 1,1*81.56 10 786.87 78.69 12 691* .69 57.89 1.36 S x H Male 20 2,328.78 3 390.73 130.21* 17 1,938.05 nl*.oo l . l l * S x G Male k 366.68 l 12.93 12.93 3 353.75 117.92 0.11
H ■p- u> Table 6
Adjusted Birth Weights of H x G Crossbred Females (A), Number and Average of Adjusted Birth Weights of the Paternal Sisters (B), Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Weight of the Dams of the Paternal Sisters (D), and Calculated H Values
Herd IIo. No. Crossbred Paternal Sire Daughter A Sisters B CDH
Senor 5 77.15 27 95.31 81* .59 93.58 -13.66 6 85.91 27 95.31 66.22 93.58 1*.28
Madcap 1*8 91*.05 1*1* 90.59 87.50 89.16 1* .2 9 9k 10l*.61* 111* 90.59 71* .69 89.16 21.29 109 81*.65 1*1* 90.59 6 8 . 5 0 89.16 lt.39 112 76.02 1*1* 90.59 6 6 . 9 6 89.16 - 3.1*7 155 80 .92 1*1* 90.59 71*.60 89.16 - 2.39 162 88.20 1*1* 90.59 81.71* 89.16 1.32 177 87.69 1*1* 90.59 68.93 89.16 7.22
Jolly 105 81.02 1*9 91.05 75.95 89.27 - 3.37 110 67.66 1*9 91.05 66.36 89.27 -11.73 117 89.75 1*9 91.05 66.93 89.27 8.87 172 60.0 9 1*9 91.05 66.51 89.27 -19.58 2 33 76.71* 1*9 91.05 82 .5U 89.27 -10.95 2 39 91*. 98 1*9 91.05 82.1*0 89.27 7.37 288 7 6.16 1*9 91.05 69.33 89.27 - 1**92
Admiral 2.1k 75.37 25 86.66 70.35 90.21 - 1.36
Chief 212 81*.20 32 91.61 70.52 89.90 2.28 2h6 82.51 32 91.61 71.61 89.90 .01* 252 86.57 32 91.61 75.71* 89.90 2.01*
Rotarian 225 90.7U 33 90.62 60 .61* 92.83 16.22
Dean 253 81.27 17 93.1*7 1*8.28 91.57 9.1*1* 3kh 76.78 17 93.1*7 58.10 91.57 .05
Alex 280 78.11 15 90.01* 6 8 . 6 7 89.39 - 1.57 CK 1 Topnan 332 78.17 35 90.91* 78.81 85.61* •
25 individuals, 9 sires. Sum of positive - negative H values in Table 6 = 6.75
Sum of squares of all H values = 2,030*2101 / £L rjt' \ 2 Minus connection for sum of squares ^ — 1.8225 25 Corrected sum of squares = 2,028*3876
Mean of H ~ 6*75 * 25 = 0.27
The t-test was run on the basis of individuals as the value of
F was not significant.
Mean square of II values = 2,028*3876 ♦ 21; = 8lu5l62
Variance of mean of II = 8U*5l62 ♦ 25 = 3*3806
t = * 3 . = - £ L — - 0.11,7 “ I 3.3806 1.8386
At 2h degrees of freedom the t-value was not significant.
Maternal effects on birth weights of G x H and H x G females* The methods for determining the difference in maternal effects, and testing for heterosis were outlined by Comstock (28). In the Holstein x
Guernsey data, A and C both contain a Guernsey maternal effect, and
B and D each contain a Holstein maternal effect.
Hence (A-B) - (C-D) contains i (M - M^) 2 where M_ is maternal effect for Guernseys, and is maternal effect for Ilolsteins.
In like manner (A-B) - (C-D) for the Guernsey x Holstein data contains i (Mh - M g i . 2 Therefore H-j_ is an estimate of an effect due to heterosis + J (Mg - M^) and H2 is an estimate of an effect due to heterosis + ■§■ (M^ - M ) where H-^ = H for the Holstein x Guernsey data, and = H for the Guernsey x Holstein data. 1U6
The difference in maternal effects (Mh - M ) can be estimated as
- H-^. Using the means obtained, H2 - H-j_ = 7 .UU - 0.27 = 7.17 as the estimate of IV - M • h g The variance of the estimate is the sum of the variances of the
two H's which is 3.7273 + 3.3806 = 7.1079 • Applying the t-test,
= = iaz_ = 2-689 7.1079 2.666
The t-value was significant at the 1 per cent level for $1 degrees
of freedom. (27 + 2U) , which indicated that maternal effects were
significant.
Test for heterosis. The average of the means estimates the
heterosis effect unconfounded by maternal effect.
% + **2 0,27 + 7#i^ = 3.86 2 2 1 The variance of this average is 4 (3.7273 + 3.3806) = 1.7770.
Applying the t-test,
t = = 2.896 >/ 1 . 7 7 7 0 1.333
The t-value was significant at the 1 per cent level for £l degrees of
freedom (27 + 2k) • This indicates that there was heterosis for birth
weight, and that the gene action was something other than additive in
nature.
Analysis of birth weights of S x H females. Data on nine calves
and their dams were available. Thirteen calves of this combination
had been bom, but one calf was dead at birth, two were from twins,
and there was no birth weight for the dam of one calf.
For this analysis the birth weights of the crossbreds, their dams, and maternal sisters "were adjusted to 1 2 9 3 pound dam using
0.0232 which is the regression coefficient obtained for Holstein females. Likewise, the other daughters of the sires of the maternal sisters, and their dams were adjusted to the same basis. The daughters of the Brown Swiss sires, and their dams had been adjusted to 1293 pound dams using 0.0276. The reasons for adjusting the Holstein data to the Erown Swiss weight, were the similar size of the two breeds, and the lack of at least five H x S females. It was also thought that there would not be much difference between the maternal effects of Brown Swiss and Holstein dams.
The basic data are given in Appendix Table 3* and the data used in calculating the H values, and the calculated H values are given in
Table 7. 1U8
Table 7
Adjusted Birth Weights of S x H crossbred Females (A), Number and Average of Adjusted Birth Weights of the Paternal Sisters (B), Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Weight of the Dams of the Paternal Sisters (D), and Calculated H Values
Herd No. Mo. Crossbred[ Paternal Sire Daughter A Sisters B C D H
Gentleman 255 9U.06 18 87.83 86.82 9U.79 10.21
Trusty- 260 98.80 11 95.79 78.33 91.28 9»k9
Lucky 261 98.90 17 92.22 81.25 98.88 15.50 287 9k.a 7 17 92.22 10^.97 98.88 - .39
Ajax 31U 106.80 Ik 96.89 6)+. 25 98.93 27.25
Duke Dan 315 91.80 11 93.56 103.93 93.85 - 3.80
Jerry 37k 86.29 3 77.92 90.10 85.93 6.29 378 81.01 3 77.92 91.28 85.93 .kl 380 97.65 3 77.92 88.02 85.93 18.69
9 individuals, 6 sires„
Sum of positive - negative H values in Table ? = 83.65
Sum of squares of all H values = 1,580 . 7 5 7 1
Minus correction for sum of squares — 77*7^80 9 Corrected sum of squares = 1,50 3 . 0 0 9 1
Mean of H = 83.65 * 9 = 9.29
Because the value of F was not significant, the t-test was run
on individuals.
Mean square = 1,503.0091 * 0 = 18 7 .8761
Variance of mean of H = 1 8 7 .8761 + 9 ” 20.8751
t . 2^L_ = 2.03U / 20.8751 U.568 1 h9
The t-value was not significant at 8 degrees of freedom, however, it was above the 10 per cent level.
Analysis of birth weights of S x G females.. Ten females of this cross had been born up to September 30, 195>6, however, data were not available on four of them. Two calves were sired by a Brown Swiss bull whose purebred daughters were out of purchased cows. Consequently no daughter-darn comparisons for birth weight were available on this bull. The dam of one calf was not bred in the herd, and the dam of the fourth calf was not weighed when this calf was born.
The birth weights of the crossbreds were adjusted to 996 pound dams using 0.0310, which was the procedure followed for purebred
Guernsey females. The purebred daughters of the Brown Swiss bulls, and their dams were adjusted to 1293 pound dams using 0 .0 2 7 6 .
The basic data are given in Appendix Table U, and the data used in calculating the H values, and the calculated II values are given in
Table 8. 150
Table 8
Adjusted Birth Weights of S x G Crossbred Females (A), Number and Average of Adjusted Birth Weights of the Paternal sisters (B), Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Weight of the Dams of the Paternal Sisters (D), and Calculated II Values
Herd No. No. Crossbred Paternal Sire Daughter A Sisters B C D H
Ajax 283 77.31* lh 96.89 62.09 98.93 - 1.13 370 81* .50 Ik 96.89 67.15 98.93 3.50
Lucky 318 83*95 17 92.22 69.71 98.88 6.31
Duke Dan 320 eu.su 11 93.56 6 8 . ll* 93.85 U.lU 321 82.95 11 93*56 78.12 93.85 - 2.75
Gentleman 32U 7U.53 18 87*83 70.52 9h.79 - 1.16
6 individuals, i* sires.
Sum of positive - negative H values in Table 8 = 8.91
Sum of squares of all H values = 79*3907
Minus correction for sum of squares = 13.231U 6 Corrected sum of squares = 66.1593
Mean of H = 8.91 * 6 = 1.1*8
The value of F was not significant.
Mean square = 66.1593 ♦ 5 = 13*2319
Variance of mean of H = 13*2319 ♦ 6 = 2.2053
1.1*8 l.l l8 t = — .1.. = = 0.997 / 2.2053 1.1*85
The t-value was not significant at 5 degrees of freedom. As no
G x S females had ever bean born in the herd, it was impossible to determine the maternal effect of the Guernsey dams in this cross. 2$2
Table 9 (continued)
Herd No* No* Crossbred Paternal Sire Son A Brothers B C D H
Honor 11*1 95*33 1*1* 80.11* 103.20 71.58 - .62 11*1* 10l*.$2 1*1* 80.11* 61.79 71.58 29.28 11*9 117.1*6 1*1* 80.11* 103.09 71.58 21.$6 1$9 101.97 1*1* 80.11* 102.30 71.58 6.1*7 168 90.20 1*1* 80.11* 86.19 71.58 2.7 6 169 90.$8 1*1* 80.11* 86.28 71.58 3.09 171* 103.$2 1*1* 80.11* 9l*.52 71.58 11.91 180 108.7$ 1*1* 80.11* 76.21 71.58 26.29 182 83.07 1*1* 80,11* 80.30 71.58 ■ 1.1*3
Foremost 221 80.11 6 76.82 100.00 67.82 -12.80 238 78.79 6 76.82 91.32 67.82 - 9.78
Main Stay 153 90.1*7 15 7l*.7S 82.62 75.0$ 11.81 171 87*36 15 71**76 115.71 75.05 - 7.75 17$ 99.87 15 7l*.78 100.20 75.05 12.$1 176 101.02 15 7l*.78 113.62 75.05 6.96 21*9 87.98 15 7U.78 82.82 75.05 9.32 2$1* 89.31* 15 71**78 110.01 75.0$ - 2.92
Trophy 172 9U.19 12 77.76 9l*.71 75.76 6.95 177 82.01* 12 77.76 96.83 75.76 • 6.26
Fame 211 82.31* 13 7l*.79 90.67 7l*.96 - .31 222 103.50 13 7U.79 88.18 7l*.96 22.10
Lucky Lad 322 75.21 3 71.92 100.68 7i*.5i* - 9.78
Raider 31*1* 98.90 3 83.91 101.78 69.06 - 1.37
28 individuals, 11 sires*
Sum of positive - negative H values in Table 9 12$*75
Sum of squares of all H values 3,901.126$ >2 Minus correction for sum of squares $6U.7$22 28 Corrected sum of squares 3,336.371*3
Mean of H = 12$ .75 • 28 = 1*.1*9 151
Analysis of birth welghte of G x H males* Data were available on 28 male calves of this combination and their dams. Data on four calves could not be used, three because of failure to obtain the birth weight or weight of the dam at calving, and the birth weight on the fourth calf was not used because the dam was a twin.
The birth weights of these calves were adjusted to 1259 pound
dams, using 0.0317 the regression coefficient obtained for purbred
Holstein males. When male calves were involved it was necessary to
further adjust the dams' weights to put them on a male basis. The
difference between male and female calves of the Holstein breed was
5.52 pounds, so that amount was added to the adjusted weights of the
dams of the crossbreds. The basic data for the G x H males are
given in Appendix Table 5, and the data used in calculating H values,
and the calculated H values are given in Table 9.
Table 9
Adjusted Birth Weights of 6 x H Crossbred Males (A), Number and Average of Adjusted Birth Weights of the Paternal Brothers (B), Genetic Values for the Dams of the Crossbreds (c), Average Adjusted Wbight of the Dams of the Paternal Brothers (D), and Calculated H Values
Herd No. No. Crossbred Paternal Sire Son A Brothers B C D H
Holliston 1 96.72 10 79.51 118.02 70.76 - 6.1+2
Royal Oak 3 99.12 1 78.81+ 120.1+7 71+.39 - 2.76
Majesty 7 80.73 7 70.16 93.1+9 68.72 - 1.81
Hollibright iol+ 91.21+ 27 79.1+6 85.93 71+.23 5.93 151 100.82 27 79.1+6 91.32 71+.23 12.82 1S3
The value of F was not significant*
Mean square = 3*336*371*3 t 27 * 123*5691*
Variance of mean of H = 123*5691* ♦ 28 = 1**1*132
t = * 2.138 Vi.l*I32 2.10
At 27 degrees of freedom the t-value was significant at the 5 par cent level*
Analysis of birth weights of H x G males. Twenty-eight calves of this combination had been born up to September 30, 1956, with data available on 23 of them. The other five calves consisted of two for which weights were not available, one dead at birth, one whose sire could not be determined, and one whose dam was not bred at Clemson*
The weights of these calves were adjusted to 996 pound dams using the regression coefficient 0*021*2. The amount added to their dams1 adjusted birth weights to put them on a male basis was
5*03 pounds*
The basic data for the calves are given in Appendix Table 6, and the data used in calculating H values, and the calculated H values are given in Table 10* 151*
Table 10
Adjusted Birth Weights of H z Q Crossbred Males (A), Number and Average of Adjusted Birth Weight of the Paternal Brothers (B), Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Weight of the Dams of the Paternal Brothers (D), and Calculated H Values
Herd No* No. Crossbred Paternal Sire Son A Brothers BCD H
Senor 1* 9i*.8l 29 99.57 67.61* 97.67 10.26
Imperial 81* 85.87 76 100.30 71.65 97.81* - 1.33 86 79.97 76 100.30 69.01* 97.81* - 5.93
Jolly 85 75.1*2 51 95.10 65.01* 95.79 - !*.30 111 81* .02 51 95.10 69.01* 95.79 2.30 112 80.91* 51 95.10 67.57 95.79 - .05 162 90.32 51 95.10 71.21 95.79 7.51 202 89.11 51 95.10 87.02 95.79 - i.6l 209 93.21* 51 95.10 83.26 95.79 l*.l*o 230 78.36 51 95.10 72.66 95.79 - 5.18 239 91.1*2 51 95.10 87.35 95.79 .51* 252 71.18 51 95.10 83.81* 95.79 -17.91*
Madcap 160 68*66 67 96.82 76.90 96.11 -18.56 181 91.53 67 96.82 86.90 96.11 - .69
Chief 161* 88.61* 21* 9lt.93 63.50 97.71* 10.83 218 91* .13 21* 91*.93 102.12 97.71* - 2.99
Chris 216 80.19 12 99.27 76.1*3 96.55 - 9.02 282 80.63 12 99.27 75.01* 96.55 - 7.88
Topman 260 73.1*1 18 97.58 80.08 93.27 -17.57
Dean 263 83.27 1*0 97.1*7 76.69 93.39 - 5 . 8 5
Burk 372 77.78 9 97.96 80.91* 93.68 -13.81
Genius 291* 85.63 18 95.17 79.39 100.61 1.07
Captain 371* 81.76 2 97.82 79.39 10l*.68 - 3.1*2
23 individuals, 11 sires 155
Sun of positive - negative H values In Table 10 = - 79*22
Sum of squares of all H values = 1,751*4220
Minus correction for sum of squares (~12j£2) = 272.8612 23 Corrected sum of squares ■ 1,1*81.5608
The value of F was not significant*
Mean square = 1,1*81.5608 * 22 = 67 -3U37
Variance of mean of H = 67.31*37 * 23 = 2.9280
^2.9280 1.7111
The t-value was not significant at 22 degrees of freedom, however, it was above the 10 per cent level*
Maternal effects on birth weights of 0 x H and H x G males* The methods used to determine the difference in maternal effects, and test for heterosis were explained on page ll*5 and ll*6. To determine the difference in maternal effects let
1-j^ = 1 for the H x G data, and ilg = H for the G x H data.
The difference in maternal effects (Mh - M ) is Hg - which for these data is l*.l*9 + (- 3.1*1*) = 7*93* Because 3.U* was negative it was added to 1*.1*9, if it had been positive it would have been sub tracted. The variance of the estimate is the sum of the variances of the two I's which “ 1*. 1*132 + 2*9280 = 7*31*12. Applying the t-test,
The t-value was significant at the 1 per cent level for 1*9 degrees of freedom (27 + 22).
Test for heterosis. The average of 1?^ and Hg estimates the 1$6 heterosis effect unconfounded by maternal effect.
H2 - H, U.U9 - 3-W* ------=...... = 0.525• The variance of this average is 2 2
i (1*.1*132 + 2 *9280) = 1.8353.
t = .= = = = 2s£2- = 0.368 Vl.e353 1.3»7
The t-value was not significant at 1*9 degrees of freedom (27 + 22).
Analysis of birth weights of S x H males. Data on 21 calves and
their dams were available for this analysis. Pour other calves had
been b o m up to September 30, 1956. One was dead at birth, one was
sired by the Brown Swiss bull whose progeny were from purchased cows,
one was from a cow b o m as a twin, and the fourth calf was not weighed
at birth. The weights of the crossbred calves, their dams, and maternal
brothers were adjusted to 1293 pound dams using the regression co
efficients of the Holstein breed. The weights of the other sons of
the sires of maternal brothers and their dams were also adjusted to
the same basis. The amount added to the adjusted birth weights of
the dams of the crossbreds, and purebred Holsteins to put them on a
male basis was 5*81 pounds. This is 0.29 pound more than the differ
ence between the averages of Holstein males and females when adjusted
to 1259 pound dams. Because of the larger regression coefficient for
Holstein males, the difference would be expected to be 0.29 pound
more at 1293 pound dams. The birth weights of the Brown Swiss had
been adjusted to 1293 pound dams, and 7*97 pounds were added to the
dams of the paternal brothers to put them on a male basis*
The basic data are given in Appendix Table 7, and the data used to
calculate the H values, and the calculated H values are given in Table 11. 357
Table 11
Adjusted Birth Weights of S x H Crossbred Hales (A), Number and Average of Adjusted Birth Weights of the Paternal Brothers (B), Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Weight of the Dams of the Paternal Brothers (D), and Calculated H Values
Herd No. No. Crossbred Paternal Sire Son A Brothers B C DH
Gentleman 231 95.62 12 99.1*3 110.70 107.07 - 5.63 235 97.61* 12 99.1*3 9U.36 107.07 1**57 237 109.05 12 99.1*3 112.98 107.07 6.66 308 115.50 12 99.1*3 92.63 107.07 23.29 310 102.79 12 99.1*3 102.80 107.07 5.50 312 81* .52 12 99.1*3 99.29 107.07 -11.02 325 95.81* 12 99.1*3 110.78 107.07 - 5.U5 379 90.73 12 99.1*3 101.30 107.07 - 5.82
Duke Dan 23U 115.09 18 97.76 9U.11 10U.17 22.36 317 99.11* 18 97.76 123.01 10U.17 - e.oi* 367 102.1*6 18 97.76 95.23 10U.17 9.17 381* 115.78 18 97.76 102.80 10U.17 18.70
Ajax 2 96 105.98 11 102.09 90.1*2 110.80 11* .08 350 123.99 11 102.09 102.16 110.80 25.U1 366 107.53 11 102.09 96.31 110.80 12.68 378 99.1*1* 11 102.09 112.98 110.80 - 3.7U
Lucky 261 10l*.01 19 98.91 10U.38 100.1*5 3.11* 330 ioi*.51* 19 98.91 90.3U ioo.U5 10.69 352 106.71* 19 98.91 90.1*2 ioo.l*5 12.85 368 97.81 19 98.91 97.28 ioo.l*5 .U8 373 101.56 19 98.91 99.58 100.1*5 3.09
21 Individuals, 1* sires.
Sum of positive - negative H values in Table 11 = 132.97
Sum of squares of all H values = 3,170.7381
Minus correction for sum of squares = 81*1.953U 21 ------Corrected sum of squares = 2,328.781*7
Mean of H * 132.97 ♦ 21 = 6.33 158
The value of F was not significant*
Mean square *= 2,328.761x7 ♦ 20 * 116.U392
Variance of mean of H « 116*1x392 ♦ 21 = 5*51x1x7
t = = 2.688 Y 5.51x1x7 2.351x7
For 20 degrees of freedom the t-value was significant at the 2 per cent level.
Analysis of birth weights of S x G males. Nine males had "been b o m from this cross by September 30, 1958, but data were available on only five of the calves. Three of the calves were by the bull on which there were no progeny-dam comparisons. The dam of the other calf was not weighed at birth.
Tbs weights of these calves were adjusted to 996 pound dams using 0.021x2, the regression coefficient used for Guernsey males.
The amount added to the dams' adjusted weights to put them on a male basis was 5*03 pounds. The Brown Swiss calves and dams were on a 1293 dam basis. The basic data are given in Appendix Table 8, and data used to calculate the H values, and the calculated H values are given in Table 12. 2 $ 9
Table 12
Adjusted Birth Weights of S x G Crossbred Males (A) > Number and Average of Adjusted Birth Weights of the Paternal Brothers (B) > Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Weight of the Dams of the Paternal Brothers (D), and Calculated H Values
Herd No* No. Crossbred Paternal Sire Son A Brothers B C D H
Lucky 268 82.27 19 98.91 81*.71 100.1*5 - 8.77 280 83.69 19 98.91 76.26 100.1*5 - 3*12 289 96.92 19 98.91 82.80 ioo.l*5 6.83
Gentleman 31*0 72.82 12 99.1*3 85.20 107.07 -15*67 361* 91.06 12 99.1*3 78.86 107.07 5*73
5 individuals, 2 sires*
Sum of positive - negative H values in Table 12 = - 15*00
Sum of squares of all H values = 1*11*6780
Minus correction for sum of squares = 1*5*0000 5 Corrected sum of squares = 366*6780
Mean of H * - 15*00 t 5 = - 3*00
The value of F was not significant.
Mean square * 366*6780 el** 91*6695
Variance of mean of H *= 91*6695 ♦ 5 * 18*3339
t = - ^ 22- = 0.701 Vl6.3339 U.282
At 1* degrees of freedom the t-value was not significant*
Discussion* Touchberry and Tabler (ll*6) reported that Guernsey,
Holstein, and crossbred calves of these two breeds increased 0*5 pound for each 100 pound increase in weight of the dam* Two of the significant regression coefficients obtained in this study, 0*01*39 160
(P<0.01) for H x G males, and 0.01*98 for S x H (P<0.01) males approached Touchberry and Tabler’s value, but the rest of them were substantially below it* Putting these two coefficients on the basis
Touchberry and Tabler used, the calves would increase 1**39 and 1*.98 pounds for each 100 pound increase in weight of their dams. The
regression coefficients obtained in this study for purebred calves
from large numbers of data varied from 0 . 0 2 3 2 to 0.0317 with all of
them significant (PC0.01).
The estimates of heritability of birth weight varied for the
different breeds. Those for Holsteins were lowest with 0.156 from
the data on males, and 0.199 from the data on females. The estimates
for the Guernseys were 0.1*30 and 0.220 for males and females. The
estimates for the Brown Swiss were 0.51*5 and 0.789 for males and
females. The estimates for the Brown Swiss breed are high compared
to the other breeds and were obtained from fewer data* However, the
intrasire regression coefficient of 0.391*5 from the female data was
significant (PC0.02), whereas the coefficient from the data on males,
0.2726, was not significant but approached the 5 per cent level.
Tyler et al. (ll*7) obtained an average of 0.60 as an estimate of
heritability of birth weight in Holsteins using four different
methods. The 95 per cent fiducial range was 0.50 to 0.70.
'With the intrasire regression method as used here, heritability
is expressed as a fraction of the variance which existed among the
females mated to one sire. This fraction of the variance is due to
the additively genetic differences between the mates of one sire, and
includes a small part of the epistatic differences (Lush, 89)• l6l
In this discussion reference to weight is to adjusted weight.
The G x H females averaged 88.78 + 10.3U pounds, compared to the average weight of the dams of 88.60 + 10.07 pounds. The weight for the dams was almost three pounds lighter than the average for all
Holstein females. The average H value after subtracting the negatives from the positives was 7»Uh. The t-value was significant (P<0.01) at 27 degrees of freedom, therefore these females were significantly heavier than the parental mean*
The H x G females averaged 82.38 + 9.09 pounds compared to
71*01 + 10.Oii for their Guernsey dams. The average H value after
subtracting the negatives from the positives was 0 .2 7 , which was not
significantly different from the parental mean.
The difference between the females from reciprocal crosses of
the Guernsey and Holstein breeds was 6 .I4.O pounds. The difference between the average H values for the two groups was 7*17* which is
the estimate of the maternal effect of the Holstein dams for
increased birth weight over the Guernsey dams in teims of H. At 51
degrees of freedom this difference was significant (P<0*01). To
test for heterosis the maternal effect was taken out by adding the
means, and dividing by two. The result, 3*86 was significant
(P<0.01) at 51 degrees of freedom.
Heterosis for birth weight occured in the reciprocal crosses,
and the heterosis effect was actually shown in the G x H cross. The
reason the H x G calves were not larger appears to be the maternal
effect of the Guernsey dams. This probably varies for individual
Guernsey cows because one calf weighed 106 pounds at birth, and six
calves weighed between 90 and 100 pounds at birth. 162
The nine S x H females averaged 9U.S0 + 7.U8 pounds as compared to 87,23 + 12.U9 pounds for their Holstein dams. All animals involved in this comparison were put on a 1293 pound dam basis* The crossbreds were much more uniform than their dams as shown by the standard deviations. The weights of the dams ranged from 6I4..25 pounds to
10U.97 pounds. The mean of the H values was 9.29. The t-value was not significant at eight degrees of freedom, however it was above the
10 per cent level. The variance of the mean of H was higher for this group than any other group of females. Whether or not a difference for maternal effects esists between the two parent breeds could not be determined as less than five H x S females had been born up to
September 30, 1956. This was also true for the male calves. There is an indication that with larger numbers heterosis may be shown in this cross.
The six S x G females averaged 81.35 + h»3h pounds compared to
67.78 + 5*36 pounds for their Guernsey dams. This was 2.25 pounds below the average of all Guernsey calves. The average H value for this group was 1.U8, and the calculated t-value was not significant at 5 degrees of freedom. As with the H x G females it is assumed the Guernsey maternal effect was in these data. There is no possibility of determining this maternal effect for females or males as the G x S cross has never been made in the Clemson herd.
The average weight of the G x H males was 9 3 0 + 10.19 pounds,
compared to the average weight of the dams of 95*83 + 1 5 . 3 5 pounds.
The standard deviation of the weights of the dams was larger than
for the crossbred calves. This was due to the range of the dams*
actual birth weights, which was from US to 11? pounds. The mean H 163 value was U.U9* and the t-value was significant (P<0.05) at 27 degrees of freedom* These calves showed heterosis.
The average weight of the H x G males was 83»U9 + 7 and that of their dams 76*52 + 9*57 pounds* The mean H value was which means that the negative values were greater than the positive values by
—3*UU per calf. At 22 degrees of freedom the t-value was not significant so this mean did not vary significantly from the parental mean*
To obtain the value for maternal effect of the Holstein dams the means of H were added because the mean for calves from Holstein dams was positive, and that for calves from Guernsey cows negative* The total was 7*93 > and the t-value was significant ( P < 0.01) at h 9 degrees of freedom* These results are similar to those obtained from females of these reciprocal crosses.
In separating the maternal effects from a possible heterosis effect the difference between the means was divided by two, and the result was 0*525* The t-value was not significant. The G x H males showed heterosis but the H x G males were below the parental mean*
When the data from both groups were combined heterosis was not shown*
The S x H males averaged 103*61 + 9*13 pounds compared to 100*90 +
8*32 pounds for their dams* The mean value for H was 6*33 > and the t-value was significant (PC 0*02) at 20 degrees of freedom* These results indicate that these calves showed heterosis*
The S x G males averaged 85*35 + 9*16 pounds and their dams
80*11 + 5*59 pounds. When the amount added to put them on a male basis was subtracted the average of the dams was 5*05 pounds heavier than all Guernsey females. The mean H value was -3*00, and the t-value was not significant* 16U
Gestation Lengths
The manner in which the data for gestation lengths were obtained was described on pages 131 and 132. The length of gestation was calculated by counting the day after service or insemination as the first day, and the day the calf was b o m as the last day*
Data for two-breed crossbred calves of combinations involving the Brown Swiss, Guernsey, Holstein and Jersey breeds were used with data for purebred calves of these breeds.
Determination of factors affecting gestation length. Numerous studies have been made on the relationship of various factors to gestation length in dairy cattle. According to Brakel et al. (8) who made an extensive review of the literature considerable difference of opinion exists. The main concern in this study were factors which would influence the results if no adjustments were made for them.
Brakel et al. (8) stated that most studies showed that male calves were carried about one day longer than females. They also stated that in most cases, winter freshening cows had the longest and summer freshening cows the shortest gestations* Results from studies on the effect of the age of the dam were not in agreement.
It was decided to determine the effects of sex, and sequence of calving at which the calf was born which is someY/hat similar to age, and season on these data.
The gestation lengths of the purebred male and female calves of each breed were sorted, according to the order or sequence in which the calf was born into seven groups, sequences one through six and the seventh group contained all calves born at sequence seven or 165 later. The number of calves in each sequence according to breed and sex, and the average length of gestation are given in Table 13.
In order to determine if there were significant differences between the means of the seven different sequences for a breed, an analysis of variance was run, and if the value of F was not significant at the 5 per cent level no adjustments were made for sequence. There were no significant differences between sequences for Brown Swiss males, Guernsey males, or Jersey females. Groups of calves in which there were significant differences between the seven sequences were as follows with the values of F: Holstein males, (P Holstein females, 2.23 (P<" 0*05)j Guernsey females, 5.02 (P<0.01), and Brown Swiss females, 2.26 (P<0.05). "Where there were significant differences between the seven sequences an analysis of variance was run on sequences two through seven, leaving out the data for the first sequence. The only group in which there were significant differences was the Guernsey females, F =* U.6Uj (P<0.01). An analysis of variance was then run on the data for sequences three through seven, with the value of F (2.58), being significant at the 5 per cent level. An analysis of variance was then run on the data for sequences four through seven, and the value of F was not significant. The number of days added to the gestation lengths of calves born at those sequences where significant differences occurred, was determined by comparing the averages for the different sequences. The groups of calves for which adjustments were made for sequence, and the number of days added to the calves' gestation lengths are given in Table lit. The gestation lengths of all other purebred calves were not adjusted. Table 13 Average Gestation Length by Sequence, Sex and Breed Brorai Svdss Guernsey Holstein Jersey Sequence Male Female Male Female Male Female Female (no. ) (days) (no.) (days) (no.,) (days) (no.) (days) (no,,) (days) (no.) (days) (no,.) (days) 1 Ill 289.8 38 286,1; 139 285.2 121 283.1 157 277.5 161 277.2 82 277.6 2 36 289.7 26 287.8 115 286.0 110 283.2 151 279.2 127 277.6 66 278.0 3 25 291.8 22 288,2 69 286.8 69 281,1 95 279.5 110 278.6 52 278.1 1 16 292.1; 18 287.5 19 286.8 51 281.8 87 280,0 66 279.3 31 278.5 CO ro 12 10 292.0 • 5 291.1 12 285.1 37 281.6 17 279.1 58 —~o 18 278,8 6 11 289.0 5 290.1* 2k 285.9 27 286.0 13 278.8 30 277.5 17 278.8 7 9 293.k 5 293.8 17 287.1 12 287.1 55 280.3 51 278.6 27 279.7 Totals and Averages 150 290.6 121 288.1 185 286.0 157 281.2 635 279.0 603 278.1 296 278.2 167 TABLE Hi Days Added to Gestation Length to Adjust for Sequence, by Sex and Breed. Brown Swiss Guernsey Holstein Sequence Female Female Male Female (days) (days) (days) (days) 1 1.U 1.7 1.7 o.l. 2 none 1.6 none none 3 none o.l. none none After the above adjustments had been made, an analysis of variance was run on the data for sequences one through seven for each group using the data that had been adjusted. None of the values of F were significant, which indicates that any significant differences between sequences had been eliminated. The data for three of the breeds, Brown Swiss, Guernsey, and Holstein were analyzed by analysis of variance to determine the significance of the difference in gestation length between male and female calves. Jersey males were not involved in this study. The data were tested before and after adjustment for sequence, and in each case the value of F was signi ficant at the L per cent level. The averages of the adjusted data, the difference between the males and females, and the value of F obtained from the analysis of variance are given for each breed in Table 15. 168 Table 15 Averages of Adjusted Gestation Lengths, Difference Between Males and Females, and Value of F for Each Breed Difference in Gestation Breed Males Female s Length Value of F (no.) (days) (no.) (days) (days) Brown Swiss 150 290.6 121* 288.5 2.1 9.29 -iHf Guernsey 1*85 286.0 1*57 285.1 0.9 8.91 Holstein 635 279.'* 603 278.2 1.2 20.18 •JHc -SBt Significant at 1 per cent level (P<0*01), In order to determine the effect of season, data on the male and female progery of one Guernsey and two Holstein bulls, and data on the daughters of one Jersey bull were used. These bulls were selected because they had sired the largest number of progeny within their breeds. Daughters of the Jersey bull were born from 19l*2 through 191*6. Sons and daughters of the two Holstein bulls were born from 1939 for one bull, 19U2 for the other bull, through 1950. The sons and daughters of the Guernsey bull were born from 191*6 through 1953. The data were adjusted as indicated in Table ll*. Then the gestation lengths were sorted into two groups, those for calves born between October 1 to March 31* or cool season, and those for calves born between April 1 and September 30, or warn season. The dividing of the year into two seasons was based on the fact that at Clemson the days become warmer after April 1, and cooler after October 1. The data were analysed by analysis of variance on an intrasire basis. Separate analyses were made for the male and female progeny of each sire. A summaiy of the data and analyses is given in 169 Table 16. The males born in the cool season were on the average, carried longer than those born in the warm season, however, none of the values of F were significant. In two cases, the females born in the warm season were carried longer than those born in the cool season. None of the values of F were significant. It was decided not to make any adjustment for season. Estimates of heritability of gestation length. The method used to obtain heritability estimates was that of intrasire regression of progeny on the dam, then the regression coefficient was doubled. "Where needed the gestation lengths were adjusted as indicated in Table lit. In order to put the gestation lengths of the dams of malo calves on a male basis, the difference between male and female calves of a breed was added to the gestation lengths of dams of that breed. The average adjusted gestation lengths for the progeny and their dams, intrasire regression coefficients, standard error of regression coefficient, t-value, and heritability estimate are given by sex, and breed in Table 17. Analysis of gestation lengths of G x H females. Data were available on 3U animals and their dams. Gestation lengths of crossbreds born at the first calving were adjusted by adding O.U of a day. The basic data are given in Appendix Table 9. The data given are the actual and adjusted gestation lengths of each crossbred and her dam, the adjusted gestation length of each maternal sister, the average of the adjusted gestation lengths of the paternal sisters of each maternal sister, and the average of the adjusted gestation lengths of their dams. The code name of the sire is given on the left of the page* Tab la 16 Numbers and Average Gestation Lengths of Calves by the Same Sire, Born in Warm and Cool Seasons Males Females Born in Born in Value of Born in Born in Value of Sire Breed Warm Season Cool Season F Warn Season Cool Season F (no.) (days) (no.) (days) (no.) (days) (no. ) (days) Honor Guernsey 29 285*6 28 287*2 2.09 25 283.6 26 285.2 1.76 Imperial Holstein 28 278.7 57 279.2 0.26 23 279.5 67 278.3 0.58 Major Holstein 55 277.li 70 278.2 0.35 39 276,6 59 276.9 0.05 Ena Jersey _ —— — 25 278.9 65 277.2 2.76 170 Table 17 Average Gestation Lengths, Intrasire Regression Coefficients, and Heritability Estimates for Gestation Length by Sex and Breed Ho. Average Average S. E. of Degrees of Gestation Gestation Regression Regression of Herit. Breed Sex Pairs Sires Progeny Dams Coefficient Coefficient Freedom t-Value Estimate (no.) (days) (days) (no.) B. Swiss Male 86 7 290.2 289.6 0.3183 0.0852 77 3.736 ** 0.637 B. Swiss Female 75 6 288,1 287.14 0 .11*60 0.091*8 67 1.51*0 0.292 Guernsey Male 388 28 286.0 286,0 0.309k 0.01*67 358 6,625 0.619 Guernsey Female 387 30 281*.9 28U.8 0.3065 0.01*90 355 6.255 0.613 Holstein Male 623 19 279.!* 279.8 0.2013 0.0373 602 5.397 #* 0.1*03 Holstein Female 591 21 2?8.2 278.5 O.I693 0 .01*11* 568 1**089 ** 0.339 Jersey Female 293 13 278.3 279.2 0.1590 0 .01*60 278 3.1*56 a* 0.318 Significant at 1 per cent level (P<0.01). 172 The data needed to obtain an H value for each crossbred using Equation (1) are given in Table 18. These data are the adjusted gesta tion length (A) of the crossbred, the number and average of the adjusted gestation lengths (B) of her sire's purebred daughters, the genetic value for her dam (C), and the average adjusted gestation length of the dams of the paternal sisters (D). Table 18 Adjusted Gestation Lengths of G x H Crossbred Females (A), Number and Average of Adjusted Gestation Lengths of Paternal Sisters (B), Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Gestation Length of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters B C D H Holliston 1 270 Ji k 28)4.6 279.il 28U.O - 3.90 2 278. h h 28U.6 282.0 28U.0 - 5.20 3 27 8. h h 28U.6 275.1 288.0 - 1.75 Average 278.ii li 28U.6 278.8 28U.0 - 3.60 Majesty 7 280.0 111 286.2 275.2 286. u - 0.60 Knight 18 278.0 19 287.3 280.6 285. U - 6.90 Hollilier U3 285.5 13 282.9 279.3 283.8 U.75 Hollibright 52 278.0 36 28I1.6 275.9 283.6 - 2.75 128 27iuO 36 28I1.6 27)4.ii 283.6 - 6.00 Average 276.0 36 28U.6 275.2 283.6 - U.Uo Honor 100 282.0 U5 28U.1 278.2 281|o6 1.10 137 285.0 U5 281|.l 281.7 28U.6 2.35 ll|0 28ii.O ii5 28U.1 275.1 28U.6 U.65 151 283.0 U5 28)4.1 276.7 28I1.6 2.35 158 286.0 ii5 28i|.l 277.7 28U.6 5.35 170 282.0 U5 28U.1 272.ii 28I4.6 U.00 17U 277.0 U5 28U.1 279.6 281|.6 - U.60 183 28ii.O U5 281|.l 275.9 28I1.6 U.25 189 281.0 U5 28U.1 277.6 28U.6 0.U0 196 28i|.0 ii5 28U.1 282.6 28U.6 0.90 200 283.il U5 28ii.l 28U.ii 28U.6 - 0.60 Average 282.8 U5 28U.1 278.ii 28U.6 1.80 173 Table 18 (continued) Herd No. No. Crossbred Paternal Sire Daughter A Sisters B C D H Trophy 15U 286.0 15 285.9 279.6 283.6 2.10 156 282.0 15 285.9 272.5 283.6 1.65 180 282.0 15 285.9 271.7 283.6 2.05 191* 288. 1* 15 285.9 282.1 283.6 3.2 5 198 283. 1* 15 285.9 279.0 283.6 - 0.20 2l*5 2 8 3 .u 15 285.9 27 7. U 283.6 0.60 Average 28U.2 15 285.9 277.0 283.6 1.60 Main Stay 181* 279. h 19 287.3 283.0 283. U — 8.20 185 281.1* 19 287.8 282.0 283.1* - 5.70 195 28i*.i* 19 287.8 27/4.1 283.1* 1.25 271 2 8 9 . U 19 287.8 288.8 283.U - 1.10 Average 283.6 19 287.8 282.0 283.1* - 3.50 Fame 232 2 8 0 . u 13 286.9 281.1* 281*.3 - 5.05 251 285. 1* 13 286.9 281.0 281*.3 0.15 Average 282.9 13 286.9 281.2 28U.3 - 2.)*5 Raider 21*1 27 9.1* 8 285.2 276.0 285.1 - 1.25 Foremost 270 276.0 10 285.7 2 7 6 .1* 286.0 - U.90 Lucky Lad 371 283.0 3 276.8 290.1 282.5 2 .1*0 3k individuals, 12 sires. Sum of positive - negative H values in Table 18 * - 1U.65 Sum of squares of all H values =« 1*62.7175 Minus correction for sum of squares = 6.3121* Corrected sum of squares = l*56.i*05l Mean of H * - D*.65 + 3b =* - 0.1*3 An analysis of variance was run on the H values to determine whether the t-test should be made on the basis of sires or individuals, and the results are given in Table 19. The statistics obtained from analyses of variance of the H values calculated from gestation length 17 h data for the other groups of crossbreds are also given in Table 19. Because there 'were significant differences between sires the t-test was run on the basis of sires. Averages of the gestation lengths of two or more crossbred daughters of a sire, and the genetic values of their dams were obtained. These averages were then used with the averages of the purebred daughters of the sire, and their dams to calculate an H value for the sire. These data, with the calculated H values are also given in Table 18. Sum of positive - negative H values in Table 18 =» - 21.85 Sum of squares of all H values =* 158.2375 / 21 8 5^ Minus correction for sum of squares — qg ** 39.7852 Corrected sum of squares ° ll8.Ij.523 Mean of H » - 21.85 ♦ 12 - - 1.82 Mean square =* ll8.ij.523 + 11 =* IO.768I4. Variance of mean of H = IO.768I4. + 12 * 0.897U + _ - 1.82 - 1.82 „ _ — — ------a ------a - 1 . 9 2 1 J 0.897U 0.91*73 The t-value was not significant at 11 degrees of freedom. Analysis of gestation lengths of H x G females. Data were avail able on 25 animals of this cross and their dams. The gestation lengths were adjusted in the same manner as those of the Guernsey dams; 1.7 days being added to the gestation length for a first sequence calf, 1.6 days for a second sequence calf, and O.U day for a third sequence calf. The basic data are given in Appendix Table 10, and the data used to calculate H values, and calculated H values are given in Table 20. Table 19 Analyses of Variance of H Values Calculated from Gestation Length Data for Groups of Crossbreds Total Variation Variation Between Sires Variation Within Sires Degrees Sum Degrees Sum Degrees Sum Value Crossbred of of of of Mean of of Mean of Combination Sex Freedom Squares Freedom Squares Square Freedom Squares Square F G x H Female 33 456.40 11 285-97 26.00 22 170.43 7.75 3.35 ** H x G Female 24 461.08 8 207.02 25.88 16 254.06 15.88 1.63 S x H Female 9 108.08 5 94.01 18.80 4 14.07 3.52 5.34 S x G Female 6 69.72 3 32.44 10.81 3 37.28 12.43 0.87 H x J Female k 20.35 2 16.16 8.08 2 4.19 2.09 3.87 G x H Male 29 647.44 10 196.36 19.64 19 451.08 23.74 0.83 H x G Male 23 247.80 9 64.4o 7.16 14 183.40 13.10 0.55 S x H Male 21 450.85 4 4.48 1.12 17 446.37 26.26 0.04 S x G Male 5 18.11 2 1.89 0.94 3 16.22 5.41 0.17 ■a* Significant at 1 per cent level (K0.01). 176 Table 20 Adjusted Gestation Lengths of H x G Crossbred Females (A), Number and Average of Adjusted Gestation Lengths of Paternal Sisters (B), Genetic Valued for the Dams of the Crossbreds (C), Average Adjusted Gestation Length of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters B C D H Senor 5 280.7 35 280.3 285.0 279.6 - 2.30 6 285.7 35 280.3 278.7 279.6 5.35 Average 283.2 35 280.3 281.8 279.6 1.80 Madcap 58 281.7 52 278.5 297.2 277.8 - 6.50 95 285.5 52 278.5 282.0 277.8 5.90 109 282.0 52 278.5 283.2 277.8 0.90 112 285.5 52 278.5 280.7 277.8 5.55 177 283.0 52 278.5 280.7 277.8 3.15 155 285.5 52 278.5 282.9 277.8 3.55 162 285.6 52 278.5 292.3 277.8 - 0.05 Average 283.8 52 278.5 285.6 277.8 i.5o Jolly 105 283.0 55 279.3 280.8 276.6 1.60 110 273.0 55 279.3 286.7 276.6 -11.35 117 282.5 55 279.3 280.7 276.6 1.05 172 275.0 55 279.3 275.6 276.6 - 3.80 23.3 277.7 55 279.3 285.6 276.6 - 5.6o 2 35 275.7 55 279.3 281.0 276.6 - 5.80 288 283.7 55 279.3 292.0 276.6 - 3.30 Average 278.6 55 279.3 283.0 276.6 - 3.90 Admiral lU-i 275.0 25 276.3 292 .6 277.8 - 9.70 Chief 212 281.6 36 280.8 286.6 279.2 - 2.90 256 277.0 36 280.8 282.3 279.2 - 5.35 252 281.7 36 280.8 282.6 279.2. - O080 Average 280.1 36 280.8 283.8 279.2 - 3.00 Rotarian 225 280.0 36 279.6 285 .2 278.1 - 2.65 Dean 253 280.0 19 278.2 283.7 278.3 - 0.90 355 285.0 19 278.2 291.2 278.3 0.35 Average 282.5 19 278.2 287.5 278.3 - 0.25 Alec 280 276.7 17 275.6 280.7 279.0 0.25 Topman 332 282.6 38 280.5 286.0 276.6 - 2.60 2'$ individuals, 9 sires. 177 Sum of positive - negative H values in Table 20 =* — 37.1'5 Sum of squares of all H values = 517.1775 Minus correction for sum of squares *» 56.3.001 Corrected sum of squares *■ lj6l,077U Mean of H =* - 37.U5 + 25 a - 1.50 As the value of F was not significant the t-test was run on the basis of individuals. Mean square =* lj.6l.077H + 2H = 19.2116 Variance of mean of H = 19.2116 + 25 = 0.7685 t = ~ — = - 1.711 V O . 7685 0.8766 At 2b degrees of freedom the t—value was not significant, but exact ly at the 10 per cent level. In order to have the data for H x G females on a sire basis for comparison with the data on G x H females in Table 18, averages were obtained for the crossbred daughters of each sire, and their dams. These averages are also given in Table 20, with the calculated H value for each sire. The analysis on the basis of sires follows. Sum of positive - negative H values in Table 20 » - 18.55 Sum of squares of all H values =* 137.6975 Minus correction for sum of squares (,-j^.|55) a 38.2336 Corrected sum of squares = 99.H639 Mean of H = — 18.55 + 9 =* — 2*06 Mean square = 99.^639 + 8 =* 12.1x330 Variance of mean of H =* 12.1x330 + 9 “ 1.381H t = " -! £ L “ - . 1 ^ — - _ 1 . 7 5 3 >Ii.3~8lU 1.1753 The t-value was not significant at 8 degrees of freedom. 178 Maternal effects on gestation lengths of G x H and H x G females* To determine the difference in maternal effects let H^, = ^ for Holstein x Guernsey data, and H2 =• H for the Guernsey x Holstein data* The difference in maternal effects (Mg — M^) can be estimated as Hf =* ^2 * Using the means obtained from analyzing the data on the basis of sires, Hi = H2 = ( - 2.06) - ( - 1.82) => - 0.2li as the estimate of The variance of the estimate is the sum of the variances of the two H 1 s which is 1.38lli + 0.897U = 2.2788. Applying the t-test, t = r Pr2-U- „ . _ 0^ 9 V2.2788 1.5096 The t-value was not significant at 19 (11 + 8 ) degrees of freedom, which indicates that the maternal effects were not significant. Test for heterosis. The average of and H2 estimates the heterosis effect unconfounded by maternal effect. % + **2 = ( _ 2.06) + ( - 1.82) = r. 3.88 =, 2 2 The variance of this average is ^ (I.38 1 I1 1- 0.897U) * 0.5697* . „ - ±.?h - 1.9U ■ - 2.570 ✓0.5697 0.75U8 The t-value vjas significant at the 2 per cent level for 19 degrees of freedom (11 + 8). This indicates that heterosis occured for a shorter gestation, and that the gene action was something other than additive in nature• Analysis of gestation lengths of S x H females. Data were avail able on 10 calves and their purebred dams. The gestation lengths of calves born at the first sequence were adjusted by adding 0.U day. This 179 ■was "the procedure followed with purebred Holstein females. The basic data are given in Appendix Table 11, and the data used in calculating H values, and the calculated H values are given in Table 21. Table 21 Adjusted Gestation Lengths of S x H Crossbred Females (A), Number and Average of Adjusted Gestation Lengths of Paternal Sisters (B), Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Gestation Length of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters B C DH Duke Dan 250 281.1. 11 289.2 281.1 287.6 - 6.20 315 279.li 11 28 9.2 278.0 287.6 - 5.oo Gentleman 255 279.li 18 283.2 280.0 288.9 o.65 Trusty 260 279.li 11 292.1 275.1 289.2 - 5.8o Lucky 261 275.li 16 2 9 0 . ll 268.0 288.1 - U.95 287 288.0 16 290.1 281.0 288.1 - 0.35 Ajax 31U 281.1 12 288.7 283.0 283.8 - 3.90 Jerry 37U 282.0 3 291.9 282.5 286.5 - 7.90 378 277.0 3 291.9 271.7 286.5 - 9.00 380 276.1- 3 291.9 276.0 286.5 -10.25 10 individuals, 6 sires. Sum of positive - Negative H values in Table 21 ** - £2.70 Sum of squares of all H values =» 385.81 Minus correction for sum of squares =t 277.73 Corrected sum of squares ** 108.08 Mean of H = - £2.70 + 10 » - 5.27 The value of F was not significant 18 0 Mean square = 108.08 + 9 3 12.0089 Variance of mean of H =* 12.0089 + 10 =* 1.2009 t . =-1 * 2 2 - - = - j » g Z - - - ii.809 V1.2009 1.0959 At 9 degrees of freedom the t-value was significant at the 0.1 per cent level (Snedecor, 137). These results indicate that the gestation lengths were significantly shorter than the average of the two parental breeds* Analysis of gestation lengths of S x G females. Data were avail able on 7 calves of this cross and their dams. Four of the calves were born at the first sequence, and their gestation lengths were adjusted by adding 1.7 days which was the same procedure followed with purebred Guernsey females. The basic data are given in Appendix Table 12, and the data used in calculating H values, and the calculated H values are given in Table 22. Table 22 Adjusted Gestation Lengths of S x G Crossbred Females (A), Number and Average of Adjusted Gestation Lengths of Paternal Sisters (B), Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Gestation Length of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters B C D H Ajax 283 287.7 12 288.7 279.7 283.8 1.05 370 283.0 12 288.7 285.6 283.8 - 6 . 6 0 Lucky 318 288.7 16 290. Ij 288.6 288.1 - 1.95 3 6 I4 2 8 U .0 1 6 2 9 0 .U 2 8 2 . 0 2 8 8 . 1 - 3.35 181 Table 22 (continued) Herd No. No. Crossbred Paterna 1 Sire Daughter A Sisters B C D H Duke Dan 320 287.7 11 289.2 298. 287.6 - 6.90 321 285.7 11 289.2 286.9 28 7 . 6 - 3.3-5 Gentleman 321* 28k.0 18 283.2 286.6 288.9 1.95 7 individuals, k sires. Sum of positive — negative H values in Table 22 - 18.95 Sum of squares of all H values 121.0225 18 95)2 Minus correction for sum of squares (- . 51.300k 7 Corrected sum of squares 69.7221 Mean of H » - 18.95 + 7 » - 2.71 The value of F was not significant Mean square = 69.7221 -*■ 6 = 11.620k Variance of mean of H =* 11.620k ♦ 7 = 1.6600 t - ~ 2*'7y- » ^ _ 2.103 V l . 6600 1.2881* The t—value was not significant at 6 degrees of freedom, however, it was above the 10 per cent level. Analysis of gestation lengths of H x J females. Six females of this cross were born, but the gestation length of one calf could not be used because it was dead at birth. The actual gestation lengths of the crossbreds were used which was the procedure followed with the Jersey relatives. The gestation lengths of Holstein paternal sisters, and their dams were adjusted for sequence. The basic data are given in Appendix Table 13, and the data used 182 -bo calculate H values, and the calculated H values are given in Table 23, Table 23 Gestation Lengths of H x J Crossbred Females (A), Number and Average of Adjusted Gestation Lengths of Paternal Sisters (B), Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Gestation Length of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters B C D H Chief 2U3 281.0 36 280.8 280.8 279.2 - 0 .6 0 25U 278.0 36 280.8 279.6 279.2 - 3 .0 0 262 281.0 36 280.8 286.0 279.2 - 3 .2 0 Jolly 2Ulj 2 7 5 .0 5U 279.3 281.7 27 6 .6 - 6 .8 5 Chris 2h& 2 7 2 .0 U-j 276.9 2 7 5 .0 2 7 9 .1j - 2 .7 0 5 individuals, 3 sires. All H values were negative. Total - 16.35 Sum of squares of all H values 73.8125 Minus correction for sum of squares 53.U6U5 Corrected sum of squares 20.3U80 Mean of H =* - 16.35 + 5 = - 3.27 The value of F was not significant. Mean square = 20.3U80 + U =» 5.0870 Variance of mean of H = 5.0870 + 5 = 1.017^ t - -A-?? = -■ .3._27 . = _ 3.2U2 V1 .0 1 7 U 1 .0087 There were h degrees of freedom, and the t-value was significant at the 5 per cent level. Analysis of gestation lengths of G x H males. Data were available on 30 males of this cross. The gestation lengths were adjxisted in the 183 same manner as those of purebred Holstein males by adding 1,7 days to the gestations for calves born at the first sequence. The gestations of the Holstein dams were adjusted to a male basis by adding 1.2 days. The basic data are given in Appendix Table lU, and the data used in calculating H values, and the calculated H values are given in Table 2U. Table 2l* Adjusted Gestation Lengths of G x H Crossbred Males (A), Number and Average of Gestation Lengths of Paternal Brothers (B), Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Gestation Length of the Dams of the Paternal Brothers (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Son A Brothers BC D H Holliston 1 280.7 9 2 8 5 .6 2 9 2 .8 285.7 - 8.1*5 2 285.7 9 2 8 5 .6 283. h 285.7 1.25 Royal Oak 3 2 8 2 .0 1 2 8 1 .0 28U.5 27U.O - U.25 Majesty 7 290.7 8 2 8 9 .2 2 8 2 .6 285.5 2.95 Hollibright 10U 285.7 29 283.7 2 7 8 .2 2 8 5 .6 5 .7 0 151 2 8 5 .0 29 283.7 277.3 2 8 5 .6 5.1*5 Honor lU i 2 8 8 .0 hi 285.8 2 7 6 .8 28 U.6 6 .1 0 11*1* 2 8 7.0 hi 285.8 25U.1 28U.6 16.1*5 lit? 289.0 hi 2 8 5 .8 2 8 2 .6 28U.6 U.2 0 159 2 8 6 .0 hi 2 8 5.8 28 U.2 28I4..6 o .5o 168 278.7 hi 2 8 5 .8 27U.8 28U.6 - 2 .2 0 169 279.7 hi 2 8 5 .8 277.2 28U.6 - 2 .1*0 17U 28U.7 hi 2 8 5 .8 277.2 28U.6 2 .6 0 180 281.7 hi 2 8 5.8 279.6 281*. 6 - 1 .6 0 182 287.7 hi 285.8 2 7 8 .2 28 U.6 5 .10 Main Stay 153 2 9 0 .0 18 289.5 275.7 286.7 6 .0 0 2h9 2 8 6 .0 18 289.5 275.7 286.7 2 .0 0 171 289.7 18 289.5 278.7 286.7 U.2 0 175 296.7 18 289.5 288.9 286.7 6 .1 0 176 2 8 9 .0 18 289.5 283.5 286.7 1 .1 0 25U 287.7 18 289.5 281.5 286.7 0 .8 0 Foremost 238 283.0 6 28U.8 277.3 283.6 1.3 5 221 282.0 6 28iu8 279.0 283.6 - o.5o 184 Table 24 (continued) Herd No. No. Crossbred Paternal Sire Son A Brothers B C D H Trophy 172 285.7 14 285.6 280.2 285.7 2.85 177 295.7 Da 285.6 285.5 285.7 10.20 Fame 211 282.7 13 288.5 281.2 284.9 - 3.95 222 290.7 13 288.5 274.2 284.9 7.55 241 286.7 13 288.5 276.9 284.9 2.20 Luc Icy Lad 322 280.0 3 280.3 280.2 286.5 2.85 Raider 344 285.0 3 285.3 283.2 283.7 - 0.05 30 individuals, 11 sires. Sum of positive - negative H values in Table 24 74.00 Sum of squares of all H values 829.9700 (74.00)2 Minus correction for sum of squares 182.5333 30 Corrected sum of squares 6U7.U367 The value of F was not significant0 Mean square => 647.4367 ♦ 29 “ 22.3254 Variance of mean of H = 22.3254 + 30 =* 0.7442 t - - M l - . 2.863 " V O . 714*2 0. 8 6 2 7 For 29 degrees of freedom the t-value was significant at the 1 per cent level. Analysis of gestation lengths of H x G males. Data were available on 2h calves and their dams. As no adjustment was made for Guernsey male calves the gestation lengths of these crossbred calves were not adjusted. The Guernsey dams were put on a male basis by adding 0.9 day to their gestation lengths, which had previously been adjusted for 185 sequence* The basic data are given in Appendix Table l5> and the data used in calculating H values, and the calculated H values are given in Table 25. Table 25 Gestation Lengths of H x G Crossbred Males (A), Number and Average of Adjusted Gestation Lengths of Paternal Brothers (B), Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Gestation Length of the Dams of the Paternal Brothers (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Son A Brothers B C DH Senor h 286.0 32 282.2 286.3 280.1 o J 6 Imperial 8U 279.0 8U 279.1 288.9 280.3 - hJiO 86 282.0 8U 279.1 278.2 280*3 3.95 Jolly 85 283.0 56 279.6 286.1 279.U 0.05 111 278.0 56 279.6 278.2 279. U - 1.00 112 281.0 56 279.6 282.8 279.U - 0.30 162 280.0 56 279.6 287.3 279. >4 - 3.55 202 288.0 56 279.6 289.9 279.U 3.15 209 285.0 56 279.6 287.9 279Jt 1.15 230 282.0 56 279.6 285.8 279.U - 0.80 239 282.0 56 279.6 285.U 27 9. h - 0.60 252 276.0 56 279.6 286.9 279.U 7.35 Madcap 160 275.0 69 280.2 286.7 279.2 - 8.95 181 286.0 69 280.2 292.9 279.2 - 1.05 Chief l6It 285.0 25 280.0 28U.7 278.7 2.00 218 282.0 25 280.0 290.5 278.7 - 3.90 Chris 216 276.0 12 275.9 277.9 280.0 1.15 217 282.0 12 275.9 290.2 280.0 1.00 282 27U.0 12 275.9 285.6 280.0 - u.70 Dean 263 280.0 U5 280.3 289.1 279.1 - 5.30 3U7 283.0 U5 280.3 287.5 279.1 - i.5o 186 Table 25 (continued) Herd No. No. Crossbred Paternal Sire Son A Brothers B C DH CM 3 Genius 29U 283.0 19 281.1 288.5 280.5 i Captain 37U 278.0 2 277.5 288.5 279.2 - U.15 Burk 372 2 76.0 10 276.6 286.6 276*8 - 5.50 2h individuals, 10 sires. Sinn of positive - negative H values in Table 25 = - U2.25 Sum of squares of all H values =* 322.1775 Minus correction for sum of squares “ 7U.3776 Corrected sum of squares =* 2U7»7999- Mean of H * - U2.25 + 2k = - 1.76 The value of F was not significant* Mean square - 2U7.7999 23 ** 10,7739 Variance of mean of H =» 10.7739 ♦ 2ii = O^JqiqS? - 1.76 - 1.76 £ “ — ? \ ------2 .627 k/o 7 U W 0.67 For 23 degrees of freedom the t—value was significant at the 2 per cent level. Maternal Effects on gestation lengths of G x H and H x G males. To determine the difference in maternal effects let Hi » H for the H x G males, and H2 = H for the G x H males. The difference in maternal effects (M^ - M g ) is H2 — Hi which for these data is 2.U7 + (— 1.76) =* U.23. Because 1*76 was negative it was added 187 bo 2,1*7, if it had been positive it would have been subtracted. The variance of the estimate is the sum of the variances of the two H's which »=* 0.741*2 + 0.4489 a 1*1931. Applying the t-test, t =* ... ^ 4^23— ^ 3.872 - n/1.1931 1.0923 At 52 degrees of freedom (29 +23) the t-value was significant at 0.1 per cent level. These results will be discussed after the re maining analyses on gestation lengths have been presented. Test for heterosis. The average of and H2 estimates the hete rosis effect unconfounded by maternal effect. \ \ m 2.47 - 1.76 3 0.71 „ 2 2 2 The variance of this average is ^ (0.714*2 + 0.1*489) * 0*2983 . 0.355 0.355 n ,.n t ** . •-— - =* ------= 0.650 “ V 0.2983 0.51*61 At 52 degrees of freedom (29 + 23) the t—value was not significant. Analysis of gestation lengths of S x H males. Data were available on 22 calves and their dams. Gestation lengths of calves born at the first sequence were adjusted by adding 1.7 days. Gestation lengths of the Holstein dams were put on a male basis by adding 1.2 days. The basic data are given in Appendix Table 16* and the data used to calculate H values, and the calculated H values are given in Table 2 6 . 188 Table 26 Adjusted Gestation Lengths of S x H Crossbred Males (A), Number and Average of Gestation Lengths of Paternal Brothers (B), Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Gestation Length of the Dams of the Paternal Brothers (D), and Calculated H Values Herd No. No. Cr0 s sbred Pa te r m 1 Sire Son A Brothers B C D H Gentleman 231 283.0 12 285 .0 288.2 289.6 - 1.30 235 280.7 12 285.0 281*. 2 289.6 - 1.60 237 280.0 12 285.0 279.2 289.6 0.20 308 288.0 12 285.0 281.2 289.6 7.20 31 0 287.7 12 285.0 287.2 289.6 3.90 312 267.7 12 28 5.0 281.2 289.6 -13.10 325 282.0 12 285.0 285.2 289.6 - 0.80 379 276.7 12 285.0 278.2 289.6 - 2.60 Duke Dan 238 281.7 18 289.1* 275.3 290.2 - 0.25 381* 289.0 18 289. >* 287.2 290.2 1.10 317 286.7 18 289.1* 286.2 290.2 - 0.70 367 282.0 18 289.8 27U.2 290.2 0.60 Ajax 378 285.0 11 292.6 279.2 289.9 - 2.25 296 288.7 11 292.6 281*.2 289.9 - 1.05 350 296.0 11 292.6 283.2 289.9 6.75 366 281.0 11 292.6 278.2 289.9 - 5.75 Lucky 261 282.7 19 290.1* 286.6 289.0 - 6.50 352 281*. 0 19 290.8 288.2 289.0 - 8.0 0 330 289.0 19 290.1* 283.0 289.0 1.60 368 291.7 19 290.1* 277.2 289.0 7.20 373 281*.0 19 290.1* 282.9 289.0 - 3.35 Jerry 356 280.7 2 285.5 28O06 288.6 - 0.80 22 individuals, 5 sires. Sum of positive - negative H values in Table 26 - 15.50 Stun of squares of all K values 861.7750 2 Minus correction for sum of squares (— 3-5.50) 22 10.9208 Corrected sum of squares 850.8586 Mean of H * - 15.5 22 * - 0.70 1 8 9 The value of F was not significant Mean square =* U90.89U6 + 21 =* 21.U693 Variance of mean of H * 21.U693 ♦ 22 = 0.9799 - 0.70 - 0 . 7 0 t 3 ' =* = — 0*708 V0.9799 0.9879 The t—value was not significant at 21 degrees of freedom. Analysis of gestation lengths of S x G males. Data were available on six calves of this cross. As no adjustments were necessary for Guernsey males, gestation lengths of these calves were not adjusted. The dams were put on a male basis by adding 0.9 day. The basic data are given in Appendix Table 17, and data used to calculate H values, and the calculated H values are given in Table 27• Table 27 Gestation Lengths of S x G Crossbred Males (A), Number and Average of Gestation Lengths of Paternal Brothers (B), Genetic Values for the Dams of the Crossbreds (C), Average Adjusted Gestation Length of the Dams of the Paternal Brothers (D), and Calculated H Values Herd Mo. No. Crossbred Paterna1 Sire Son A Brothers B C D H Lucky 268 289.0 19 290.1. 289.3 289.0 0.1.9 280 286.0 19 290.L 281.6 289.0 - 0.70 289 28U.O 19 290.1l 283.9 289.0 - 3.89 Gentleman 3U0 280.0 12 289.0 278.3 289.6 0.69 36U 279.0 12 289.0 2 8 3 .k 289.6 - 2 . 9 0 Trusty 369 290.0 21 292.1. 289.9 289.2 - 2.79 6 individuals, 3 sires 1 9 0 Sum of positive - negative H values in Table 27 = — 9*10 Sum of squares of all H values = 31.9100 2 Minus correction for sum of squares ^-- 6~~~~^ = 13»8017 Corrected sum of squares “ 18.1083 Mean of H 3 - 9.10 -«■ 6 =■ — 1.52 The value of F was not significant. Mean square = 18.1083 ♦ 5 - 3.8217 Variance of mean of H =» 3.6217 -» 6 = 0 . 6 0 3 6 - 1.52 - 1.52 „ t =• —======------1.956 Y 0 . 6 0 3 6 0 . 7 7 6 9 The t-value was not significant at 5 degrees of freedom • Discussion. The averages of the actual gestation lengths of male and female calves of the Brown Swiss, Guernsey, and Holstein breeds, and Jersey females were a3.1 within the range reported by Brakel et al. (8), except for the Guernsey males. The average gestation length for the Guernsey males was 286.0 days. The average gestation length for first born calves was less than the average for second calves in all groups of purebreds except Brown Swiss males, which were carried 0.1 day longer than the males born at second calvings. A limited amount of adjusting for sequence was done but it was sufficient to eliminate the significant differences which had previously existed. The difference between the gestation lengths of male and female calves was significant (P<0.01) in the Brovm Swiss, Guernsey and Holstein breeds. The effect of season when the year was divided into two periods, warm and cool was not clear cut. Males born in the cool season were 191 carried longer than males b o m in the warm season. This was also true for the daughters of two bulls, but, the daughters of two bulls b o m in the warm season were carried longer than those born in the cool season. On an intrasire basis there were no significant differences between calves of the same sex born in the two seasons. The estimates of heritability of gestation length ranged from 0,292 to 0.637* The estimate 0.292 was based on a regression coeffi cient which was not significant. All other estimates were within the range given by Rollins et al. (125)* and based on significant regression coefficients. The G x H females averaged 281.9 + 3*^9 days compared to 278.8 + U.20 days for their Holstein dams. The differences between sires were significant in this group (P analyzed on a sire basis. The crossbreds were - 1.82 below the parental mean in terms of H, but the difference was not significant. The H x G females averaged 280.9 + 3.81 days compared to 28U.li + J+.86 days for their Guernsey dams. The average H value after sub tracting the negative values from the positives was — 1.50. The t— value was not significant, but was at the 10 per cent level. In order to determine maternal and heterosis effects the data for the H x G females were put on a sire basis for comparison with the data on the G x H females. The difference from the parental mean was - 2.06, which was not significant. The difference between the average gesta tion lengths of G x H and H x G females was one day. Both groups were below the parental mean, and the H x G group was farthest from the parental mean by - 0.2U in terms of H. Applying the t-test the difference between the two crossbred 192 groups was not significant, so there was no evidence of maternal effects on female calves when Guernseys and Holsteins were crossed® To test for heterosis the mean H values, — 2.06 and — 1.82, were averaged. The average was — 1.9U, and the calculated t—value was significant (P<0oCB). These results indicate that there were inter actions of genes in the reciprocal crosses, and that heterosis for a shorter gestation length occurred. The 10 S x H femad.es averaged 280.3 + 3.8U compared to 278.9 + 5*10 days for their Holstein dams. Ondy one calf showed a positive H value, which was 0.65, all the others were minus. The average after subtracting the positive value wras — 5*27. At 9 degrees of freedom the t-value was highdy significant (P^O.OOl). The calf that showed a positive H value was sired by a bull whose purebred daughters averaged 283.2 days. The purebred daughters of the sires of the other cross breds averaged from 288.7 to 292.1 days. The Holstein dams were slight ly above the average for all Holstein females. Sxifficient data were not available on females from the reciprocal cross (H x S), to determine if there is a difference in maternal effects between Brovm Swiss, and Holstein cows. Until this is known the shorter gestation length of the crossbreds when compared to the parental mean can not with certain ty, be attributed to heterosis. The 7 S x G females averaged 285.8 + 2.23 days compared to 287.0 +5.82 days for their dams. Five of the seven dams happened to be above the average for all Guernsey females. The average H value for this group was - 2.71. The t—value was not significant, but was above the 10 per cent level. The five H x J females averaged 277• + 3»91 days compared to 193 280.0 + 3.9^4 days for the Jersey dams. Three Holstein sires vrere represented, and the averages for their purebred daughters were 280.8, 279.3> and 276.9 days. All H values for the daughters were minus and the average was — 3*27. This difference from the parental mean was significant (P 40.05) at H degrees of freedom. Crossbreds from the reciprocal cross (J x H), were not available to determine the differ ence in maternal effects between Holstein and Jersey cows. If there are none this would be a case of heterosis. The average gestation length for G x H males was 286.3 + U.33 days, compared to 279.7 + 7.27 for their Holstein dams, and the average H value was 2.1j7. At 29 degrees of freedom the t-value was signifi cant (P<0.01), therefore these calves had gestations significantly longer than the average of the parental mean. The H x G males had gestation lengths that averaged 280.9 + 3.80 days, compared to 286.L + 3.86 for their Guernsey dams. The average H value was - 1.76, which was below the parental mean. There were 23 degrees of freedom, and the t—value was significant at the 2 per cent level (P<0.02). To test maternal effects the means for G x H and H x G males were added as one was positive and the other negative. The total was l|.#23j and the t-value was significant (P< 0.001) at 52 degrees of freedom. The t-test for a possible heterosis effect was not significant. The results from reciprocal crosses of the Guernsey and Holstein breeds were different depending on the sex of the calves. Both groups of females were below the parental mean, and maternal effects were not significant. The average H value of the two groups was significantly (P<0.02) different from the parental means. This indicates that 19k heterosis occurred for shorter gestation. The average gestation length of the G x H males was 5.2 longer than the average for the H x G males. The average H value was positive for the G x H males, and negative for the H x G males. Based on the fact that maternal effects were not significant in the data on females, and that the gestations of the males were more like those of the breed of sire, it appears as though the test for maternal effects actually measured differences between breed of sire. The fundamental difference between male and female calves from reciprocal crosses of these breeds is in the sex chromosomes. The evidence indicates that genes for gestation length are carried on the Y chromosome. The 22 S x H males averaged 28U.O + 5*75 days, and their dams averaged 282.3 + 3*92 days. The average H value was — 0.70, and the t-value was not significant. The 6 S x G males averaged 28U.7 + U.55 days, compared to 283.3 + 3*90 days for their dams. The average H value was — 1.52, and the t-value was not significant. 195 Measurements of Growth of Calves The two measures of growth used in this study were body weight, and circumference of fore chest which is commonly known as the heart girth measurement* Body weight was measured in pounds, and circumference of the fore chest in centimeters* Measurement of the mammary glands, and the obtaining of body weights and heart girth measurements of female calves was started in July, 191+8. All of the data used in this study were obtained during the period from July, 191+8, through March, 1957 • The six months weights and measurements for calves born in September, 1956, were obtained in March, 1957* The data used were those obtained at three, five and six months of age, and it was necessary that comparable data be available on both the calf and its dam* The minimum number of crossbreds and their dams used for a measurement at a certain age was five* It was not possible to obtain the body weight and heart girth measurement on every calf at the above ages, therefore, the number of pairs of crossbreds and their dams varied for the different ages* The weights and measurements were obtained by weighing and measuring during a week, calves whose monthly birth dates occurred during that week. Consequently, there was considerable variation in the age at which calves were weighed and measured. This was eliminated by adjusting the weights, and heart girth measurements to 90, 150, and 180 days of age by interpolation and extrapolation* Weights and measurements were interpolated if actual weights and measurements had been obtained not over 1+5 days before, or 1+5 days after the 90th., l50th., or 180th. day birth date. Generally, 196 the actual weight and measurements had been obtained much closer to the birth date than the limits given. If there were weights or measurements within 10 and U5 days before the birth date, but none after the birth date adjustment was made by extrapolation. Estimates of heritability of weight and heart girth measurement. Estimates of the heritability of weight and heart girth measurement at 90, l£0, and 180 days of age in the Guernsey and Holstein breeds were obtained by the method of intrasire regression of daughter's record on dam's record. The regression coefficient was doubled to obtain the estimate of heritability. The statistics for weights are given in Table 28, and for heart girth measurements in Table 29. Negative estimates for the heritability of weight, and heart girth measurement were obtained from the 1 5 0 day, and 180 day Guernsey data. In order to obtain genetic values for the Guernsey dams of crossbreds, it was assumed that the heritability of 1 5 0 day heart girth measurement, and 180 day weight and lie art girth measure ment was 0.100. There were no calves from Guernsey cows involved in comparisons of 150 day weights. Analysis of 90 day weights of G x H females. The weights of the G x H females, their dams, their maternal sisters, and the average weights of the paternal sisters of the maternal sisters, and their dams, and the number of paternal sister-darn pairs at 90, 1 5 0 , and 180 days of age are given in Appendix Table 18. The 90 day weight data used to calculate H values are given in Table 30. These data consist of the weight of each crossbred calf (A), average weight and number of the paternal sisters to the crossbred (B), the genetic value for the dam of the crossbred (C), the average weight of the Table 28 Average Weights, Intrasire Regression Coefficients, and Heritability Estimates for Weight at 90, 1$0, and 180 Days of Age Age No. Average Average S. E. of Degrees in of Weight Weight Regression Regression of Herit. Breed Days Pairs Sires Daughters Dams Coefficient Coefficient Freedom t-Value Estimate (no.) (It.) (lb.) (no.) Guernsey 90 5i 11 175. h 161,8 0.1301 0.1132 38 1.11*9 0,260 Guernsey 150 53 13 263.1 238.5 - 0.0180 0.0880 38 - 0.201* - Guernsey 180 56 12 313.8 269.9 - 0.029U 0.0790 1*2 - 0.372 - Holstein 90 Sh 8 229.6 216.5 0.1093 0.0983 uu 1.112 0.219 Holstein ISO 65 10 332.8 309.3 0.26?8 0.0932 53 2.873 ** 0.536 Holstein 180 73 10 386.8 351.2 0.2161* 0.0983 61 2.201 # 0.1i33 * Significant at 5 per cent level (P^0.05). Significant at 1 per cent level (P^O.Ol). Table 29 Average Heart Girth Measurements, Intrasire Regression Coefficients and Heritability Estimates for Heart Girth Measurement at 90, l£0, and 180 Days of Age Average Average Age No. Heart Heart S. S. of Degrees in of Girth Girth Regression Regression of Herit. Breed Days Pairs Sires Daughters Dams Coefficient Coefficient Freedom t-Value Estimate (no.) (cm.) (cm.) (no.) Guernsey 90 50 11 9 U 93.9 0,2260 0.1511 37 1.509 0,1-56 Guernsey 150 56 13 109.lt 106.5 - 0.C509 0.1018 h i - 0.500 m Guernsey 180 58 11 115.2 111.6 - 0.0690 0.0835 45 - 0.826 •» Holstein 90 53 8 103.3 102 .h 0.2206 0.1290 1*3 1.710 o . l i i Holstein 150 63 9 117.5 115.3 0.2517 0.1036 52 2.U30 * 0.503 Holstein 180 72 10 123.1 120.3 0.2862 0.1035 60 2,765 ** 0.572 ■a Significant at 2.5 per cent level (P<0,025). ■a* Significant at 1 per cent level (P<0.01). 199 dams of the paternal sisters (D), and the calculated H value for each crossbred* Table 30 Weights of G x H Crossbred Females at 90 Days (A), Number and Average Weight of the Paternal Sisters of the Crossbreds (B), Genetic Values for the Dams of Crossbreds (C), Average Weight of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters B CD H Honor 170 239.2 2 181.1* 2ll*.0 1 67.8 31* .70 189 21*1.0 2 181.1* 178.5 167.8 5 U . 25 200 239.7 2 181.1* 209.1 167.8 37.65 Main Stay 181* 1 9 8 . 0 8 166.7 195.1* 11*3.8 5.5 0 185 218.1 8 166.7 208.1 11*3.8 19.25 271 222.3 8 166.7 213.8 11*3.8 20.60 Trophy 19U 220.2 3 169.6 236.0 15U.U 9.80 21*5 211.0 3 169.6 218.7 15U.1* 9.25 Fame 232 211*. 1 5 1 62.1 222.7 171.1 26.20 251 191.0 5 162.1 251.1 171.1 - 11.10 Raider 21*1 192.9 2 166.8 187.1* 158.8 1 1 . 8 0 Foremost 21*2 230.0 1 197.0 186.8 125.5 2.35 270 208.8 1 197.0 231.5 125.5 - 1*1.20 13 individuals, 6 sires* Sum of positive - negative H values in Table 30 = 179.05 Sum of squares of all H values — 9>223.3025 Minus correction for sum of squares ^ 1 3 *,Q5 ) = ------2,U66.Q69l* Corrected sum of squares = 6,757*2331 Mean of H = 179.05 ♦ 13 =13.77 200 An analysis of variance was run on the H values, and the statistics are given in the first line of Table 31• The value of F was not significant. Statistics from the other analyses of variance run on H values calculated from weight data are also given in Table 31. Mean square = 6,757.2331 + 12 = 563.1028 Variance of mean of H — 563.1028 13 = U3.3156 s = = 1 2 i Z Z _ = 2 .092 Vh3.31$6 O.iHlh For 12 degrees of freedom the t-value was not significant, however, it was not far below the 5 per cent level. Analysis of 90 day weights of H x G females. The basic data for weight at 90, and 180 days for the H x G females are given in Appendix Table 19. There were not enough crossbreds whose dams had been weighed at five months to make five comparisons for weight at 150 days. The calculated H values, and the data used to obtain them are given in Table 32. Table 31 Analyses of Variance of H Values Calculated from Weight Data for Groups of Crossbred Females Total Variation Variation Between Sires Variation Within Sires Age Degrees Sum Degrees Sum Degrees Sum Value Crossbred in of of of of Mean of of Mean of Combination Days Freedom Squares Freedom Squares Square Freedom Squares Square F G x H 90 12 6,757-23 5 lt,?5l.3li 950.27 7 2,005.89 286.56 3.32 ISO 11 6,627.37 5 3 ,186. 76 637*35 6 3,lil*0*6l 573 Ji3 1.11 180 13 15,653.27 5 1 0 ,752.07 2,150 .la 8 1;, 901.20 612.65 3.51 H x G 90 6 2,572.05 3 977.51 325.85 3 l,59h.Sl 531.30 0.61 180 5 7,21i*.70 2 1,11-0.82 570.21 3 6,07iu28 2 ,021;.76 0.28 8,750.01 1 616.02 616.02 U.liO 'O S x H 150 3 8,133.99 2,711.33 OO CM k 1 — • 1 180 S 10,266.11 k 7,817.50 1,961.87 1 2,108.61 0.81 CO 1 o — 1 S x G k 1(91.89 3 U90.53 163*51 1 1.36 1.36 120.23 201 202. Table 32 Weights of H x G Crossbred Females at 90 days (A), Number and Average Weight of the Paternal Sisters of the Crossbreds (B), Genetic Values for the Dams of Crossbreds (C), Average Weight of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters BC DH Chief 212 169.6 9 237.2 128.7 213*14 - 25.25 2U6 201*6 9 237.2 1143.5 213. U - .65 252 1914.6 9 237.2 166*8 213 .li - 19.30 Jolly 233 198.8 2 229.5 193.0 208.0 - 23.20 239 237*1 2 229.5 169.0 208.0 27.IO Topman 332 206*0 9 232.9 191.0 199.0 - 22.90 Madcap 162 217.1 5 228.6 161*5 209.0 12.25 7 individuals, U sires* Sum of positive - negative H values in Table 32 = - 51.95 Sum of squares of all H values = 2,957*5975 Minus correction for sum of squares = 385*5^4-32 7 Corrected sum of squares = 2,572*0514-3 Mean of H = - 51.95 ♦ 7 = 7.142 The value of F was not significant* Mean square = 2,572*0514-3 ♦ 6 = 1*28 .6757 Variance of mean of H = U28.6757 ♦ 7 = 61. 23914 t = = _ 0 .9il6 ^61.23914 7.8256 At 6 degrees of freedom the t-value was not significant* 203 Maternal effects on 90 day weights of G x H and H x G females. In the analysis of the birth "weights it was found that the G x H females averaged 6.2*0 pounds heavier at birth than the H x G females* The difference between the average H values for the two groups was 7*17* and this difference was significant (P<0.01). At 90 days of age the G x H females averaged 13*9 pounds heavier than the H x G females, and the difference in terms of H was 21.19. To determine if this difference was significant the data were analyzed in the same manner as the birth weights. Let HX = H for H x G females, and H 2 = H for G x H females. The difference in maternal effects (M^ - Mg) can be estimated as "H2 - which for these data is 13*77 + (-7 *U2) = 21.19* The variance of the estimate is the sum of the variances of the two H values which = 61.2391* + i*3.315>6 10l*.555>0. Applying the t-test, 21.19 21.19 t = -- = ------= 2 .072. vaou.555o 10.2252 For 18 degrees of freedom (12 + 6 ) the t-value of 2.072 was just slightly below the value of 2.101 which is at the 5 per cent level. Test for heterosis. The average of H-^ and estimates the heterosis effect unconfounded by maternal effect. H 2 - H-, 13.77 - 7.1*2 ------= ------= 3.18 2 2 The variance of this average is ^ (6l.239l* + 2*3.3156) = 26*1388. t = = 0.622 V^26.1388 5.1126 The jt-value was not significant at 18 degrees of freedom (12 + 6)• 20k Analysis of 150 day weights of G x H females* The data used in calculating H values, and the calculated H values are given in Table 33. Table 33 Weights of G x II Crossbred Females at 15>0 days (A), Number and Average Weight of the Paternal Sisters of the Crossbreds ( B ) , Genetic Values for the Dams of Crossbreds (C), Average Weight of the Dams of the Paternal Sisters (D), and Calculated II Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters BC D H Honor 200 350.0 2 262.1 318.8 260.1 58.55 Main Stay 184 316.3 6 252.4 274.5 211.0 32.15 185 328.8 6 252.4 309.2 211.0 27 .30 199 312.0 6 252.4 333.6 211.0 - 1.70 Trophy 194 291.9 4 264.6 320.6 241.1 - 12.45 198 304.0 4 264.6 289.5 241.1 15.20 245 313.5 4 264.6 323.6 241.1 7.65 Fame 232 308.7 6 252.9 317.8 248.0 20.90 251 281.6 6 252.9 341.0 248.0 - 17.80 Raider 241 295.0 3 245.2 287.3 262.4 37.35 Foremost 242 348.2 2 279.7 277.3 234.0 46.85 270 314.5 2 279.7 323.5 234.0 - 9.95 12 individuals, 6 sires. Sum of positive - negative H values in Table 33 = 204.05 Sum of squares of all II values = 10,097.0675 2 Minus correction for sum of squares^-?^^ = 3.469.7002 12 ------Corrected sum of squares = 6,627.3673 Mean of H = 204.05 ♦ 12 = 17.00 The value of F was not significant. 205 Mean square = 6,627*3673 ♦ 11 = 602.1+879 Variance of mean of H = 602.1+879 ♦ 12 = 50*2073 t = -, = il=22_ = 2.399 /SO .2073 7.08S7 For 11 degrees of freedom the t-value was significant at the 5 per cent level. Analysis of 150 day weights of S x II females. The basic data for weights at 150, and 180 days on S x H females are given in Appendix Table 20. The data used in calculating H values, and the calculated H values are given in Table 3l+* Table 31+ Weights of S x K Crossbred Females at 150 Days (A) > Number and Average Weight of the Paternal Sisters of the Crossbreds (B), Genetic Values for the Dams of Crossbreds ( c ) , Average Weight of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters B c DH Duke Dan 250 330.0 3 363.1; 361.8 333.2 - 1+7 .70 315 365.1 3 363.1; 361.8 333.2 - 12.60 Trusty 260 385-0 2 335.2 323.3 319.1; 1+7.85 Lucky 261 322.2 2 373 .1+ 356.5 317.8 - 70.55 Ajax 3H+ 367.0 6 335.2 31+0.2 297.2 10.30 5 individuals, 1+ sires® Sum of positive - negative H values in Table 3l+ — - 72*70 Sum of squares of all R values = 9,807*0650 Minus correction for sum of squares C" *7.?) = 1,057.0580 5 ------Corrected sum of squares = 8,750*0070 206 Mean of H = - 72.70 * 5 = ~ H*.51* The value of F was not significant. Mean square = 8,750.0070 ♦ 1* — 2,187*5017 Variance of mean of H = 2,187*5017 ♦ 5 ” 1*37*5003 t = = - 0.695 /l*37.5003 20.9165 The t-value was not significant at 2* degrees of freedom. Analysis of 180 day weights of G x H females. The data used in calculating the H values, and the calculated H values are given in Table 35* Table 35 Weights of G x H Crossbred Females at 180 Days (A), Number and Average Weight of the Faternal Sisters of the Crossbreds (B), Genetic Values for the Dams of Crossbreds (C), Average Weight of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters B C D H Honor 170 395*0 2 326.0 295*0 291* .2 - 68.60 189 U18.5 2 326.0 268.1* 291*.2 105.1*0 200 U08.5 2 326.0 375*6 291**2 1*1.80 Main Stay 181* 375*6 8 291**0 298.0 21*3*7 51* .1*5 185 367.5 8 29U.O 31*6.7 21*3.7 22.00 199 383. h 8 291**0 382.0 21*3.7 20.25 271 381*. 0 8 29U.O 355.5 21*3.7 31* .10 Trophy 19k 337.2 3 30k. 8 31*7.6 27l*.0 - 1* .1*0 198 362.1 3 301*. 8 338.2 27U.O 25.20 21*5 31*7.6 3 301*. 8 365.3 271*.0 - 2.85 Fame 232 378. h k 301.2 37U.1* 279.8 29.90 251 33k. 8 k 301.2 3 9 9 .0 279.8 - 26.00 Raider 21*1 31*1.2 1 273.2 331.6 353.0 78.70 Foremost 21*2 395.0 3 31*0.6 322.2* 292.1* 39.1*0 lit Individuals, 6 sires. 207 Sum of positive — negative H values in Table 35 = i+86.55 Sum of squares of all H values = 32,562.6175 Minus correction for sum of squares (U86.55) = 16^909.3502 Hi Corrected Sum of Squares = 15,653.2673 Mean of H = U86.55 ♦ Hi — 3U.75 The value of F was not significant. Mean square = 15,653.2673 ♦ 13 = 1,201*.0975 Variance of mean of H = 1,201*.0975 ♦ Hi = 86.0070 t = 3U>75 _ 3lt>75 = 3_7ii7 ” /86.0070 9.27U0 For 13 degrees of freedom the t-value was significant at the 0.5 per cent level (Snedecor, 137) • Analysis of 180 day weights of H x G females. The data used to calculate the H values, and the calculated H values are given in Table 3 6 • Table 3 6 Weights of H x G Crossbred Females at 180 days (A), Number and Average Weight of the Paternal Sisters of the Crossbreds (B), Genetic Values for the Bams of Crossbreds (C), Average Weight of the Dams of the Paternal Sisters (D), and Calculated H Values Hei*d No. No. Crossbred Paternal Sire Daughter A Sisters B c D H Madcap 162 317.8 5 389.2 2 7 0 . 1 321.6 - U5.65 Chief 212 273.5 12 391.6 2 2 5 . 6 339.5 - 6 1 . 1 5 2JU.6 351*. 8 12 391.6 2 3 6 . 0 339.5 lit .95 2 5 2 370.1 12 391.6 3 0 5 . 9 339.5 - 2*.70 Jolly 2 3 3 339.7 2 37 5 .0 313.6 298.7 - 1+2.75 239 387.9 2 375.0 256.3 298.7 3U.10 6 individuals, 3 sires. 208 Sum of positive - negative H values in Table 36 = - 105,20 Sum of squares of all H values — 9>059*2100 Minus correction for sura of squares ^ = l,8i4U.5067 6 Corrected sum of squares = 1 y2lh»1033 Mean of H = - 105.20 «- 6 = - 17.53 The value of F was not significant* Mean square = 7,21^*7033 + 5 — lyhh2 .91*07 Variance of mean of H = 1,UU2*9U07 ♦ 6 = 2l|.0.U901 - 17*53 - 17*53 t - = — = - 1.130 Y 2 h 0 .1*901 15.5077 For 5 degrees of freedom the jt-value was not significant* Maternal effects on 180 day weights of G x H and H x G females* To determine the difference in maternal effects let H-^ = H for the H x G females, and Hg = H for the G x H females. The difference in maternal effects (M^ - Mg) is Hg - wil^-ch ^or these data is 3U.75 + (- 17*53) = 52.28. The variance of the estimate is the sum of the variances of the two H's which = 8 6 . 0 0 7 0 + 2H0.U901 = 326.^971* t = J M ^ r = = 2.853 vS26.U97i 18.0692 For 18 degrees of freedom (13 + 5) Ihe t-value was significant at the 1 per cent level. Test for heterosis. The average of and estimates the heterosis effect unconfounded by maternal effect. Ho ~ H-, 3U.75 - 17*53 — = = 8.61 209 The variance of this average is | (86*0070 + 21+0.1+901) = 81.621+3* i - = 0.953 '/81.62U3 9 .031+6 For 18 degrees of freedom (13 + 5) the t-value was not significant. Analysis of 180 day weights of S x H females. The data used in calculating H values, and the calculated H values are given in Table 37. Table 37 Weights of S x H crossbred Females at 180 Days (A) , Number and Average Weight of the Paternal Sisters of the Crossbreds (B), Genetic Values for the Dams of Crossbreds (C), Average Weight of the Dams of the Paternal Sisters (D), and Calculated H values Herd N o . No. Crossbred Paternal Sire Daughter A Sisters B CD H Duke Dan 230 383.6 3 1+18.1+ 1+20.8 385.0 - 52.70 315 i+i+i.o 3 1+18.1; 396.5 385.0 16.85 Gentleman 255 1+12 .0 9 391+.7 386.9 359.1 3.1+0 Trusty- 260 1+27.9 3 1+02.9 362.8 368.2 27.70 Lucky 26l 360.7 3 398.6 1+11.1+ 382.1 - 52.55 Ajax 3lU 1+56.2 5 386.8 380.9 363.2 60.55 6 individuals, 5 sires. Sum of positive - negative H values in Table 37 = 3.25 Sum of squares of all H values = 10,267.8675 Minus correction for sum of square= ______1.7601+ 6 Corrected sum of squares — 10,266.1071 Mean of H = 3.25 ♦ 6 = 0.51+ The value of F was not significant. 210 Mean square = 10,266,1071 ♦ 5 = 2,053.2211+ Variance of mean of H = 2,053.2211+ * 6 = 31+2,2036 s . S lS k. = _2sS!l_ = 0.029 \6 i+2.2036 16 .1+987 For 5 degrees of freedom the _t-value was not significant. Analysis of 160 day weights of S x G females. The basic data on 180 day weights for the S x G females are given in Appendix Table 21. The data used to calculate H values, and the calculated H values are given in Table 38. Table 38 Weights of S x G Crossbred Females at 180 Days (A), Number and Average Weight of the Paternal Sisters of the Crossbreds (B), Genetic Values for the Dams of Crossbreds (C), Average Weight of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters B CD H Ajax 283 3 8 0 . 2 5 3 8 6 . S 329 .5 363.2 1 0 . 2 5 Lucky 318 386,14. 3 398.6 288.9 3 8 2 . 1 31+.1+0 361+ 1+01.1 3 398*6 315.0 382.1 36.05 Duke Dan 3 2 1 1+00.5 3 1+18.1+ 310.1+ 385.0 19.1+0 Gentleman 3 2 l+ 31+6.6 9 391+.7 2 2 5 . 6 359.1 18.65 5 individuals, I* sires. 211 Sura of positive - negative H values in Table 38 — 118.75 Sura of squares of all H values = 3,312.2075 d i g Minus correction for sum of squares'-— = 2,820.3125 Corrected sura of squares = 1*91.8950 Mean of H = 118.75 * 5 = 23.75 The value of F was not significant. Mean square = 1*91.8950 t li = 122.9737 Variance of mean of H = 122.9737 ♦ 5 — 2l*.59l*7 t = £M1_ = 2ME_ = u .789 /2U.59U7 h.9593 At 1* degrees of freedom the t-value was significant at the 1 per cent level. Analysis of 90 day heart girth measurements of G x H females. The basic data on heart girth measurements at 90, 150, and 180 days for the G x H females are given in Appendix Table 22. The data used to calculate H values for 90 day measurements, and the calculated H values are given in Table 39. 212 Table 39 Heart Girths of G x H Crossbred Females at 90 Days (A), Number and Average Heart Girth of the Paternal Sisters of the Crossbreds (B)> Genetic Values for the Dams of Crossbreds (C), Average Heart Girth of the Dams of the Faternal Sisters (D), and Calculated H Values Herd No. No. Cros sbred Paternal Sire Daughter A Sisters BC DH Honor 170 1 0 2 .5 2 9 2.2 97.2 93.5 8.1*5 189 101* .0 2 92.2 97.5 93.5 9.80 2 0 0 1 1 0 . 2 2 9 2 . 2 1 0 1 . 1 93.5 11*.20 Average 1 0 5 . 6 2 92.2 98.6 93.5 10.85 Main Stay 181; 97 .5 8 93.1* 1 0 0 . 5 90.8 - 0.75 1 8 ^ 100.9 8 93.1; 98.7 90.8 3.55 271 102.3 8 93.1* 1 0 2 . 0 90.8 3.30 Average 1 0 0 . 2 8 93. h 1 0 0 .1* 90.8 2 .00 Trophy 19U 103.1 3 95.1 103.5 92.1* 2.1*5 21*5 1 0 0 . 8 3 95.1 101.3 92.1* 1.25 Average 1 0 2 . 0 3 95.1 1 0 2 .1* 92.1* 1 . 9 0 Fame 232 101.3 5 91.1* 102.5 96.0 6.65 251 97.8 5 91.U 1 0 7 . 8 96 .0 0 . 5 0 Average 99.6 5 91 .U 10 5 . 2 9 6 . 0 3.60 Raider 21*1 98.0 2 96.6 95.0 93.1; o.6o Foremost 21*2 1 0 3 . 0 l 99.0 9 6 .1* 88.2 - 0 . 1 0 2 7 0 1 0 0 . 1 1 99.0 101*.o 8 8 . 2 - 6.80 Average 1 0 1 . 6 1 99.0 1 00.2 8 8 . 2 - 3.1*0 1 3 individuals, 6 sires. Sum of positive - negative H values in Table 39 = 1*3.10 Sum of squares of all H values = 1*91.7850 Minus correction for sum of squares = 11*2.8931 13 Corrected sum of squares = 31*8.8919 213 An analysis of variance was. run on the H values, and the statistics; are given in the first line of Table UO. The value of F was signi ficant at the 5 cent level. Statistics from the other analyses of variance run on H values calculated from heart girth data are also given in Table 1*0. Because sire differences were significant the data were analyzed on the basis of sires. In order to do this it was necessary to calculate an average for the daughters (A), and an average of the genetic values of the dams (C), where there were two or more daughtei’S of a sire. The averages are shown in Table 39, with the H values calculated from averages. The data on one daughter of a sire was used as it appears in the table. The analysis on the basis of sires is given below. Sum of positive - negative H values in Table 39 = 19 Sum of squares of all H values — 150.2125 Minus correction for sum of squares Q 26 2 P .') = ------ItO.30024. Corrected sum of squares = 109*9121 Mean of H = 19.59 ♦ 6 = 2.£9 Mean square = 109*9121 * 3 — 21.982U Variance of mean of H = 21 .982I4. * 6 = 3.6637 t = 2 2 2 — = 2 2 2 — = 1 . 3 5 3 . 6 6 3 7 1 .9 1 U1 For 5 degrees of freedom the t-value was not significant. Analysis of 90 day heart girth measurements of H x G females. The basic data on heart girth measurements at 90, 15>0, and 180 days for the H x G females are given in Appendix Table 23. The data used to calcu late H values for 90 day measurements, and the calculated H values are Table 1*0 Analyses of Variance of H Values Calculated from Heart Girth Data for Groups of Crossbred Females Total Variation Variation Between Sires Variation Within Sires Age Degrees Sum Degrees Sum Degrees Sum Value Crossbred in of of of of Mean of of Mean of Combination Days Freedom Squares Freedom Squares Square Freedom Squares Square F G x H 90 12 3li8<.89 5 277.07 55.1*1 7 71.82 10.26 5.1*0 * iSo 11 131.16 5 68.67 13.73 6 62.1*9 1 0 .1a 1.32 180 13 180 o3i* 5 130.1*0 26,08 8 1*9.91* 6.21* 1*.18 * H x G 90 6 80,1*1* 3 25.88 8.63 3 5U.56 18.19 0.1*7 150 1* b6.93 1 26.79 26.79 3 20.11* 6.71 3.99 180 6 90.36 2 17.21 8.60 1* 73.15 18.29 0.1*7 S x H 150 1* 89.95 3 77.1*1* 25.81 1 12.51 12.51 2.06 180 5 179.11* 1* 162.90 1*0.72 1 1 6 .21* 1 6 .21* 2.51 S x G 180 1* 20.ll* 3 20.06 6.69 1 0.08 0.08 83.62 * Significant at 5 per cent level (P<0,05). 215 given in Table 1*1. Table IfL Heart Girths of H x G Crossbred Females at 90 days (A), Number and Average Heart Girth of the Paternal Sisters of the Crossbreds (B), Genetic Values for the Dams of Crossbreds (C)> Average Heart Girth of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters BCD H Chief 212 95.6 9 10U.5 86.7 102.7 - 0.90 21*6 101.2 9 10U.5 89.9 102.7 3.10 252 96.1; 9 IOU.5 9U.6 102.7 - U.05 Average 97.7 9 101* .5 90.1* 102.7 - o.6§ Jolly 233 97.8 2 IOI4.U 97.0 101.6 - !*.30 239 105.3 2 IOI4.I4 96.8 101.6 3.30 Average 101.6 2 lOU.l* 96.9 101.6 - 0.1*$ Topman 332 99.0 8 101* .7 98.3 100.1 - U .80 Madcap 162 101.0 5 102.3 9l*.6 101.8 2.30 7 individuals, h sires. Sum of positive - negative H values in Table I4I — 5*35 Sum of squares of all H values = 8U.5325 Minus correction for sum of squares 5*35) _ 1^.0889 7 Corrected sum of squares = 8O.l4J4.36 Mean of H = - $.3$ + 7 = -O.76 The value of F was not significant. Mean square = 8O.I1I436 t- 6 = 13.1*073 Variance of mean of H = 13.14073 * 7 = 1.9153 ' - 0.76 - 0.76 t = — ■ . ,_l.’ = ------= - 0.51*9 ✓1.9153 1.3839 For 6 degrees of freedom the t-value was not significant. 216 The data on H x G females were analyzed on the hasis of sires, in order that a comparison could be made with the G x H females for maternal and heterosis effects* The average of two or more daughters of each sire (A), and the average of the genetic values of their dams (C), ar3 given in Table 1*1 with the H values calculated from the averages. When a sire had only one daughter the data for that daughter were used for the sire* The analysis is shown below* Sum of positive - negative II values in Table 2*1 s= - 3.60 Sum of squares of all II values = 28*9550 2 Minus correction for sum of squares 3 «6p) _ 3.22*00 2; Corrected sum of squares = 25*7150 Mean of H = - 3 . 6 0 ♦ I* = - 0*90 Mean square = 25*7150 * 3 = 8*5717 Variance of mean of H = 8*5717 ♦ 2* = 2*ll*29 - 0.90 - 0.90 _ _ t = ' . ' " = = 0.615 /2 .11*2 9 1.1*639 For 3 degrees of freedom the t-value was not significant* Maternal effects on 90 day heart girth measurements of G x H and H x G females. To determine the difference in maternal effects let = H for the H x G females, and Hg = H for the G x H females. The difference in maternal effects (M^ - M^) is which for these data is 2*59 + (- 0*90) = 3.1*5* The variance of the estimate is the sum of the variances of the two H»s which = 3.6637 + 2.12*29 = 5.8066. Applying the t-test, t = . s 3 A & — = 1.1*32 \/$ *8066 2.2*097 217 For 8 degrees of freedom (5 + 3) "the t-value was not significant* Test for heterosis* The average of and ^2 es'tima^es heterosis effect unconfounded by maternal effect* }L - H, 2*59 - 0.90 ± = ------= 0.8U 2 2 The variance of this average is \ (3*6637 + 2.1U29) = l«ii£>l6 t = SaSk- = OiSk- = 0.697 / l *U5l6 1.201*8 For 8 degrees of freedom (5 + 3) the t -value was not significant* Analysis of 150 day heart girth measurements of G x H females* The data used to calculate H values, and the calculated H values are given in Table 1*2. 218 Table 1*2 Heart Girths of G x H Crossbred Females at 150 Days (A)> Number and Average Heart Girth of the Paternal Sisters of the Crossbreds (B), Genetic Values for the Dams of Crossbreds (C), Average Heart Girth of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters BC DH Honor 200 1 2 0 .0 2 108.9 11L*.0 1 0 7 .6 7 .9 0 Main Stay 181* 111*.6 6 1 0 7 .5 1 1 0 .1 1 0 2 .9 3 .5 0 185 1 1 6 .0 6 1 0 7 .5 1 1 6. 1* 10 2 .9 1 .7 5 199 115 *U 6 107*5 1 1 8 .0 1 0 2 .9 0 .3 5 Trophy 1 9 k 1 1 3 .6 k 108.1* H U .5 1 0 6 .6 1 .2 5 198 111* .6 1* 1 0 8. 1* 1 0 9 .6 1 0 6 .6 1**70 21*5 115*5 1* 108.1* 113.7 1 0 6 .6 3 .5 5 Fame v ' 232 115*2 6 1 0 8 .9 1 1 5 .8 1 0 6. 1* 1 .6 0 251 111*5 6 1 0 8 .9 1 2 1 .8 1 0 6. 1* - 5 .1 0 Raider 21*1 111*5 3 108.1* 10 9 .1 1 0 8 .3 2 .7 0 Foremost 21*2 118.7 2 109*k 1 1 0 .8 1 0 6 .2 7 .0 0 270 lll*.l 2 109*U 1 1 6 .8 1 0 6 .2 - o .6o 12 individuals, 6 sires. Sum of positive - negative H values in Table 1*2 = 28.60 Sum of squares of all H values = 199*3200 Minus correction for s u m o f squares (28*60) = 68.1633 12 Corrected sum of squares = 131*1567 Mean of H = 28.60 ♦ 12 = 2.38 The value of F was not significant. Mean square = 131*1567 * 11 = 11.9233 Variance of mean of H = 11*9233 12 = 0.9936 2 .3 8 2 .3 8 t = ;------= = 2.388 Y’0.9936 0.9968 219 For 11 degrees of freedom the t-value was significant at the 5 per cent level* Analysis of 15>0 day heart girth measurements of H x G females* The data used to calculate H values, and the calculated H values are given in Tahle h3» Table U-3 Heart Girths of H x G Crossbred Females at 150 Days (A), Number and Average Heart Girth of the Paternal Sisters of the Crossbreds (B), Genetic Values for the Dams of Crossbreds (C), Average Heart Girth of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters BCD H Chief 212 105.6 10 117.7 99. 5 115.6 - U.05 252 111.5 10 117.7 108.8 115.6 - 2.80 Jolly 233 113.2 1 119.0 109.7 119 .U - 0.9 5 239 117 .U 1 119.0 106.5 119.U U.85 288 113.5 1 119.0 108.it 119.il 0.00 5 individuals, 2 sires* Sum of positive - negative H values in Table Jj-3 — -2*95 Sum of squares of all H values = I4.8 . 6 6 7 5 (- 2 95)^ Minus correction for sum of squares v--- tZd.* = 1.7l;05 % Corrected sum of squares = I4.6 .9 2 7 O Mean of H - -2.95 ♦ 5 = - 0*59 The value of F was not significant. Mean square — i;6 .9270 ♦ h = 11.7317 Variance of mean of H = 11*7317 ♦ 5 = 2.3H63 t = - = - 0-59 = •J2 .3U63 1.S318 ” ‘ 220 The t-value was not significant at it degrees of freedom* Maternal effects on 150 day heart girth measurements of G x H and H x G females* To determine the difference in maternal effects let H-^ = H for the H x G females, and H2 *= H for the G x H females* The difference in maternal effects (M^ - M ) is which for these data is 2*38 + (- 0.59) = 2*97* The variance of the estimate is the sum of the variances of the two H*s which is 2.3^63 + 0.9936 = 3*3399* t = Sag- = 2 t 2 2 — = 1#6as V3 .3399 1.8275 For 15 degrees of freedom (11 + U) the t-value was not significant. Test for heterosis* The average of + H2 estimates the heterosis effect unconfounded by maternal effect, H2 “ % 2.38 - 0*59 = = 0.90 2 2 The variance of this average is ^ (2.3U63 + 0.9936) = 0.8350 * = 2^22— = °i22— = 0.98S ✓0.8350 0.9138 For 15 degrees of freedom (11 + ij.) the t-value was not significant. Analysis of 1$0 day heart girth measurements of S x H females. The basic data on 150, and 180 day heart girth measurements of S x H females are given in Appendix Table 2h» The data used to calculate H values, and the calculated H values are given in Table UU. 221 Table I4JL4. Heart Girths of S x H Crossbred Females at 150 Days (A), Humber and Average Heart Girth of the Paternal Sisters of the Crossbreds (B), Genetic Values for the Dams of Crossbreds (C), Average Heart Girth of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No* Crossbred Paternal Sire Daughter A Sisters B C D H Duke Dan 250 lliuO 3 118.9 1 1 8 . 0 117*1 - 5.35 315 1 1 9 . 0 3 118.9 118.0 117.1 - 0.35 Trusty 260 U 6.6 3 115.8 1 1 7 . 0 115*5 0.05 Lucky 261 113.6 3 119.5 11.6.0 115.7 - 6.05 Ajax 3114 122.3 6 111*. 3 117*1; 112.7 5.65 5 individuals, 1; sires. Sum of positive - negative H values in Table Hj- = 6*05 Sum of squares of all K values = 97*2725 Minus correction for sum of squares = 7*3205 5 Corrected sum of squares = 89*9520 Mean of H = - 6.05 ♦ 5 = - 1-21 The value of F was not significant. Mean square - 89*9520 ♦ U = 22.U880. Variance of mean of H = 22.H880 * 5 — li*i*976 - 1*21 _ - 1.21 t = = 0.570 VI .2*976 2.1208 The t-value was not significant at 1* degrees of freedom. Analysis of 180 day heart girth measurements of G x H females, The data used in calculating H values, and the calculated H values are given in Table 1+5« 222 Table 1*5 Heart Girths of G x H Crossbred Females at 180 Days (A), Number and Average Heart Girth of the Paternal Sisters of the Crossbreds (B) , Genetic Values for the Dams of Crossbreds (C)* Average Heart Girth of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Si sters BC DH Honor 170 119.0 1 113.7 111*.3 115.6 5.95 189 1 2 5 . 0 1 113.7 111.5 115.6 13.35 200 122* .5 1 113.7 121.1 115.6 8.05 Average 122.8 1 113.7 115*6 1 1 5 . 6 9.10 Main Stay 181* 121.8 8 113.6 115.8 108.1 i*.35 185 121.8 8 113.6 1 1 7 . 6 108.1 3.1*5 199 122.3 8 113.6 123.7 108.1 0.90 271 121* .1 8 113.6 120.5 108.1 1+.30 Average 122.5 8 113.6 119.U 108.1 3.25 Trophy 19U 121.0 3 Hi* .7 119.9 110.7 1.70 198 120.3 3 lli*.7 116.1* 110.7 2.75 2 1*5 120.8 3 111*. 7 119.5 110.7 1.70 Average 120.7 3 111* .7 118.6 110.7 2.05 Fame 232 121.1 1* lllul 122.8 113.9 2.55 251 118.8 2* 112*.1 128.1 113.9 - 2.1*0 Average 120.0 1* 11U.1 125 .1* 113.9 0 . 1 5 Haider 22*1 117.1 1 111 .i* 116.3 117.5 6.30 Foremost 21*2 123.7 3 117.1 116.3 111*.3 5.60 ll* individuals, 6 sires. Sum of positive - negative H values in Table 1*5 — 58.£5 Sum of squares of all II values = 1*25.2075 Minus correction for sum of squares = 2i*l*.861*5 ll* Corrected sum of squares = 180.31*30 Because the differences between sires were significant, the analysis of the data was made cn the basis of sires. The average of the daughters of each sire (A), the average of the genetic 223 values (C) of their dams, and the H values calculated from the averages are also given in Table U5 • The analysis on the basis of sires follows. All H values wer) positive, total = 26.1*5 Sum of squares of H values for sires = 166.6U75> Minus correction for sum of squares izD = 1 1 6»6Q0U 6 Corrected sum of squares = 52.0lj.71 Mean of H = 26.U5 * 6 = U-Ul Mean square = 52.0U71 ♦ 5 = 10.1+09U Variance of mean of H = 10.U09U ♦ 6 = 1.73U9 t = kiiii— - — = 3. 3U8 V I .7 3U9 1 .3 1 7 2 For 5 degrees of freedom the t-value was significant at the 2,5 per cent level. Analysis of 180 day heart girth measurements of H x G females. The data used to calculate H values, and the calculated H values are given in Table U6. As the data for the G x H females were analyzed on the basis of sires these data were analyzed on the basis of individuals, and sires* The averages needed to calculate H values for sires are also given in Table U6. The analysis on the basis of individuals will be given first. 221* Table I4.6 Heart Girths of H x G Crossbred Females at 180 Days (A), Number and Average Heart Girth of the Paternal Sisters of the Crossbreds (B), Genetic Values for the Dams of Crossbreds (C), Average Heart Girth of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters B c D H Madcap 162 113.5 5 122.1 1 1 0 .U 117.1 - 5.25 Chief 212 112 .1 12 1 2 3 .u ioii.2 119.5 - 3.65 2 h 6 121.1 12 123 .U 1 0 8 . 2 119.5 3.35 252 118.8 12 1 2 3 .1+ 1 1 U .9 119.5 - 2.30 Average 117.3 12 1 2 3 .h 1 0 9 . 1 119.5 - 0.90 Jolly 233 119.0 2 1 2 1 . 9 1 1 U.U 115.0 - 2 . 6 0 239 12U.3 2 1 2 1 . 9 1 1 0 . 3 115.0 U.75 288 117.3 2 1 2 1 . 9 1 :15.2 1 1 5 . 0 - ii.20 Average 120.1+ 2 1 2 1 . 9 H 3 . 3 115.0 - 0.65 7 individuals, 3 sires. Sum of positive - negative H values in Table U6 = 9.90 Sum of squares of all H values = 10lj..3600 Minus correction for sum of squares (- 9.90)^ = lU.OOlii- 7 Corrected sum of squares = 90.3586 Mean of H — - 9.90 ♦ 7 = - l.Ul The value of F was not significant. Mean square = 90.3586 *• 6 = 15.0598 Variance of mean of H ” 15*0598 t 7 = 2.l5lU t = = ~ — = - 0.961 V2.151U 1.U668 For 6 degrees of freedom the t-value was not significant. The analysis on the basis of sires is on the next page. 225 All H values were negative, total = - 6*80 Sum of squares of all H values = 28*79f?0 Minus correction for sum of squares s= 15.U133 3 ------Corrected sum of squares = 13*3817 Mean of H = - 6.80 ♦ 3 = - 2.27 Mean square = 13*3817 ♦ 2 = 6,6908 Variance of mean of H = 6.6908 ♦ 3 = 2.2303 -2.27 -2.27 t = ------= -----!— = - 1 . 5 2 0 /2.2303 1.U93U For 2 degrees of freedom the t-value was not significant* Maternal effects on 180 day heart girth measurements of G x H and H x G females. To determine the difference in maternal effects let H-^ = H for the H x G females, and Hg — H for the G x K females. The difference in maternal effects (M^ - M ) is Hg - which for these data is l+.Ul + (- 2.27) — 6.68. The variance of the estimate is the sum of the variances of the two H's which = 2.2303 + 1.73k9 = 3.9652. , _ 6.68 _ 6.68 „ t ------— ------3.35U /3T9652 1.9913 For 7 degrees of freedom (5+2) the t-value was significant at the 2 per cent level. Test for heterosis. The average of H-^ and estimates the heterosis effect unconfounded by maternal effect. Ho - Hn ii.Ul - 2.27 ± = ------= 1.0 7 2 2 The variance of this average is \ (2.2303 + 1*73>h9) = 0.9913 226 t = = ^L_ „ 1>0TS \] 0.9913 0.9956 For 7 degrees of freedom (5 + 2) -the t-value was not significant. Analysis of 180 day heart girth measurements of S x H females. The data used to calculate H values, and the calculated H values are given in Table 1*7. Table 1*7 Heart Girths of S x H Crossbred Females at 180 Days (A), Number and Average Heart Girth of the Paternal Sisters of the Crossbreds (B), Genetic Values for the Dams of Crossbreds (C), Average Heart Girth of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters B C D H Duke Dan 2 5 0 121.5 3 1 2 3 . 8 121+.7 1 2 1 . 2 - 1+.05 315 126.5 3 123.8 123.3 1 2 1 . 2 1.65 Gentleman 255 1 2 5 . 6 9 1 2 2 .1+ 123.1+ 118.1+ 0 . 7 0 Trusty 2 6 0 12U.7 5 119.7 1 2 2 . 6 123.0 5.20 Lucky 2 6 1 117.9 3 122.7 121.9 1 1 9 . 8 - 5.85 Ajax 311+ 129.1 3 115.1 123.7 116.6 10.1+5 6 individuals, 5 sires. Sum of positive - negative H values in Table 1*7 = 8.10 Sum of squares of all H values = 190.0800 /g 10^ ^ Minus correction for sum of squares —*— = 10.9350 6 Corrected sum of squares = 179.11+50 Mean of H = 8.10 + 6 . = 1.35 The value of F was not significant. Mean square = 179.11+50 * 5 = 35*8290 227 Variance of mean of H = 35*3290 * 6 = 5*9715 t = ii3S_ . = 1z35_ = 0 .S52 v 5.9715 2.Wi37 For 5 degrees of freedom the t-value was not significant* Analysis of 180 day heart girth measurements of S x G females* The basic data on 180 day heart girth measurements for S x G females are given in Appendix Table 2$, The data used to calculate H values, and the calculated H values are given in Table 2*8• Table 1*8 Heart Girths of S x G Crossbred Females at 180 Days (A), Number and Average Heart Girth of the Paternal Sisters of the Crossbreds (B), Genetic Values for the Dams of Crossbreds (C), Average Heart Girth of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No* No. Crossbred Paternal Sire Daughter A Sisters B CDH Ajax 283 121.9 3 115.1 117.6 116.6 6.30 Lucky 318 121.6 3 122.7 113.7 119.8 1.95 361* 122.1 3 122.7 115.5 119.8 1.55 Duke Dan 321 121.3 3 123.8 115 .u 121.2 0,1*0 K> H O Gentleman 321* 118.2 9 122.1* • 118.1* 2.90 5 individuals, 1* sires* All H values were positive, total = 13.10 Sum of squares of all H values = 514--U650 Minus correction for sum of squares ^ = 31**3220 5 Corrected sum of squares = 20*11*30 Mean of H = 13*10 «• 5 = 2.62 228 The value of F was significant. Mean square = 20.1U30 ♦ U ~ 5 .035 8 Variance of mean of H = 5*0358 * 5 ~ 1*0072 t = 2 . 6 U V i .0072 1.0036 The t-value was not significant at I; degrees of freedom, but was close to the 5 per cent level. Discussion. The estimates of the heritability of weight from the Holstein data were 0.219, 0.536, and 0.1;33 for weight at 90, 150, and 180 days respectively. The intrasire regression coefficient for 90 day weights was not significant but the others were, 150 days (P<0.01), and 180 days (P<0.05). None of the regression coefficients obtained from Guernsey data were significant, and only the coefficient for 90 day weights was positive. Possibly the negative regression coefficients were due to sampling errors, in that the numbers of pairs were relatively small and there were more cases in the Guernseys where a sire had only two or three daughter-darn pairs. The G x H females were heavier than their Holstein dams at all ages. They averaged 217 .It, 313*7, and 373*5 pounds at 90, 150, and 180 days compared to 210.1, 309*1, and 3l;1*3 pounds for their dams. They were above the parental mean in terms of H at each age, and the differences were significant at 150 (P<0.05), and 180 days (P<. 0.005) of age. The H x G females averaged 203*5 pounds at 90 days, and 3U0.6 pounds at 180 days compared to 163*1 and 26U.6 pounds for their dams. However, these calves were below the parental mean in terms of H by - 7 *Ii2 at 90 days, and - 17*53 at 180 days. These differences 229 from the parental means were not significant. The G x II females were 13*5 pounds heavier than the II x G females at 90 days, and 32.9 pounds heavier at 180 days. In terms of H there was a difference of 21.19 at 90 days, and £2.28 at 180 days. Using the test which was used to determine maternal effects on birth weights the difference at 90 days was not significant, but the difference at 180 days was significant (P< 0.01). The mean II values for the two groups were averaged, and tested by the t-test for heterosis. After subtracting the minus values for the H x G females and dividing by two the averages were positive, but the t-values were not significant. According to the definition of heterosis used the G x H females showed heterosis at l£0, and 180 days. Sufficient data were not available on H x G females at 1£>0 days, therefore, the test for heterosis could not be made on data from both groups. When the data for 180 day weights were combined the II x G females were so far below the parental mean, that the average H value was not significantly different from the parental means. The S x H females weighed 353»9 pounds at 150 days, and Ul3«6 pounds at 180 days compared to 3 ^4-8.7 and 393-2 pounds for their Holstein dams. The average II value was - lii.£U at l£0 days, and 0.£U at 180 days. The differences from the parental mean were not significant. The crosses between Holstein cows and Guernsey or Brown Swiss bulls produced quite different results. Apparently there is more non-additive gene interaction in the Guernsey x Holstein cross. 230 The S x G females averaged 383*0 pounds at 180 days compared to 292*7 pounds for their dams. The average H value was 23*75 and this was significantly (P< 0.01) above the parental mean. It would seem safe to call this a case of heterosis* because, if there was a difference in maternal effects between Erown Swiss and Guernsey cows it would seem as though Erown Swiss cows would be comparable to Holstein cows. This question could not be answered because G x S crossbreds have never been produced in the Clemson herd. The estimates of heritability of heart girth measurements from the Holstein data were O.lUil, 0.503 and 0-5?2 at 90, 150* and 180 days respectively. The regression coefficient at 90 days was not significant, but the t-value was above the 10 per cent level. The t-values for the regression coefficients obtained from 150 day (P<‘0.025), and 180 day data (P^O.Ol) were significant. The estimates of heritability of heart girth measurements from the Guernsey data, followed the same trends as the estimates for weight. The regression coefficient obtained from the 90 day data was 0*2280, but the t-value was not significant. The regression coefficients obtained from the 150, and 180 day data were negative, however, the t-values were not significant. The heart girths of the G x H females averaged 101.6, 115*1 and 121.5 cm. at 90, 150, and 180 days respectively, compared to 100.Uj llli.l and 118.7 cm. for their Holstein dams. Sire differences were significant in the 90, and 180 day data. The average H value was above the parental mean for each age with the difference significant at 150 days (P<0.05), and 180 days (P< 0.025). 231 The heart girths of the H x G females averaged 99*5» 112.2, and 118*1 cm. at 90, 15>0, and 180 days respectively compared to 93*6, 106.U, and 111.0 cm. for their Guernsey dams. Sire differences were not significant at any of the ages. The averages of the H values were - 0.76, - 0.f>9* and - l.Ul at 90, 15>0, and 180 days respectively* These differences from the parental mean were not significant. In the test for maternal effects the G x H females were larger around the heart girth than the H x G females at each age. In terns of H the differences were 2.97* and 6*68 at 90, 13>0, and 180 days respectively. These differences were significant only at 180 days (P<0.02). For this analysis, and to test for heterosis the 90 day, and 180 day data on the H x G females were put on a sire basis because of the sire differences in the G x H data at these ages. When the mean H values for the two groups were averaged in order to test for heterosis, the averages were positive for each age but the differences from the parental means were not significant. The average heart girths of the S x H females were 117.1* and 12li.2 cm. at 150, and 180 days compared to 117*3* and 123.3 cm. for their Holstein dams. The average H values were - 1*21 and 1.35* These differences from the parental means were not significant. The S x G females averaged 12U.2 cm. for heart girth at 180 days compared to 123.3 cm. for their Guernsey dams. The average H value of 2.62 was not significantly above the parental mean, but the t-value was above the 10 per cent level. 232 Mamma-py Gland. Grades The technique of measuring the mammary glands of heifer calves was developed by Swett (1U3). The purpose was to determine if the relative size of glands in calves of the same age could be used to predict milk production later in life* The final mammary gland grade for a calf is based upon stage, width, and length of the glands, and age of the calf. The stage depends on the closeness of the front and rear gland on one side of the udder* As the glands develop they come closer together, and eventually the tissues which are on the glands unite. The stage is given grades of A to G, and each grade is further subdivided by using a plus and minus. Therefore the three subdivisions of stage E would be E -, E, and E +. The widths of each gland are measured, and if the glands on a side are joined the overall length of the two glands is obtained* The measurements are used to calculate a figure called gland size* The mammary gland grade is then read from a nomogram by placing a straight edge at the proper point for stage, gland size, and age of the calf in weeks and days. The grades run from 1 to 9, and each grade is further divided into three subdivisions by using a plus and minus* There are twenty-seven grades running from 1 - to 9 +• The mammary gland grades for G x H females and their dams ob tained at five months of age were analyzed in this study. The measure ments used were made within ten days of the five months birth date* The measurements were made during the period July, 19U8, through December, 19SU. In order to put the grades on a numerical basis they were coded as follows:: 233 Grade Code Grade Code Grade Code Grade Code Grade Code 1 - 1 3 - 7 5 - 13 7 - 19 9 - 25 1 2 3 8 5 1U 7 20 9 26 1 + 3 3 + 9 5 + 15 7 + 2 1 9 + 27 2 - k k - 10 6 - 16 8 - 22 2 U 11 6 17 8 23 2 + 6 h + 12 6 + 18 8 + 2 U Estimates of heritability of mammary gland grade. In order "to calculate genetic values for the dams it was necessary to obtain an estimate of the heritability of mammary gland grades in Holsteins, and an estimate was calculated for animals of the Guernsey breed. The coded grades were used, and in further discussion reference to grade wilD. be to coded grades. The method used was that of intrasire regression of the daughter's grade on the dam's grade. Then the regression coefficient was doubled to obtain the heritability estimate* The statistics obtained are given in Table lj.9* Table h9 Average Grades, Intrasire Regression, Coefficients, and Heritability Estimate for the Holstein Breed No. Average Average S. E« of Degrees of Grade Grade Regression Regression of Herit. Breed Pairs Sires Daughters Dams Coefficient Coefficient Freedom t-Value Estimate (no.) (no.) Holstein 80 12 1$.? 16.6 0.1102 0.0715 66 i.51*i 0.220 Guernsey 79 15 i5.Ji 19.9 - 0.0233 0,080lj 62 - 0,290 235 Analysis of coded mammary gland grades of G x H females* The grades and coded grades are given in Appendix Table 26 for the cross breds and their dams* The coded grades for the maternal sisters, and the averages of the coded grades of the paternal sisters of the maternal sisters, and their dams are also given. The data used to calculate H values, and the calculated H values are given in Table 50. Table 50 Coded Mammary Gland Grades of G x H Crossbred Females (A), Number and Average of Coded Grades of the Paternal Sisters (B), Genetic Values for the Dams of the Crossbreds (C), Average Coded Grade of the Dams of the Paternal Sisters (D), and Calculated H Values Herd No * Mo. Crossbred Paternal Sire Daughter A Sisters B C DH Honor 158 1 7.0 2 1 7 .0 1 0.9 1 9 .0 U.05 189 18*0 2 17.0 1U.6 1 9 .0 3 .2 0 Trophy 180 17.0 3 15.0 15 08 13.7 0 .9 5 198 lU.O 3 1 5 .0 18*0 13.7 - 3.1 5 Ida in Stay 18U 1 6 .0 7 lUolj 12 .0 15.3 3.2 5 185 1 7 .0 7 Iiu 5 13.1 15.3 3 .7 0 199 1 9 .0 7 lU .ii 2h.h 15.3 0 .0 5 271 15.0 7 lU .U 1U.0 15.3 1.25 Fame 232 1U.0 7 1 5 .6 15.0 16.5 - 0.9 0 251 16 .0 7 15.6 1 6 .0 16.5 0 .6 0 Raider 2 ijl 1 5 .0 6 15 .0 1 6 .0 15.3 - 0.3 5 Foremost 270 lluO 3 13.7 1 9 .0 17.3 - 0 .5 5 12 individuals, 6 sires. 236 Sum of positive - negative H values in Table $0 12.10 Sum of squares of all H values 6U.8800 1 2 10)2 Minus correction for sum of squares ( . 12.2008 12 Corrected sum of squares 52.6792 Mean of H => 12.10 ♦ 12 = 1.01 The analysis of variance of the H values is given in Table 5l* Table 5l Analysis of variance of H values in Table 50 Source of Degrees of Sum of Mean variation freedom squares square Total 11 52.68 Sires _5 33.98 6 .80 Within sires 6 18.70 3.12 F =* 6.80 + 3.12 = 2.18. Not significant. Mean square =* 52.6792 + 11 = U .7890 Variance of the mean of H =* U.7890 + 12 = 0.3991 1.01 1.01 = 1.599 “ ^0.3991 0.6317 For 11 degrees of freedom the t-value was not significant. Discussion. The regression coefficients were quite different. Possibly, the negative coefficient for the Guernsey breed may be explained on the basis of sampling errors because of the small number of pairs for some sires. The average of the grades of the G x H crossbreds was 16.0 + 1.65, compared to the average grade of their Holstein dams of 15.7 + U.1 2 . The crossbreds were more uniform than tire dams as ehov.~ by the 237 standard deviations. The crossbreds were better than the parental mean by an average of 1*01 in terms of H, but the difference was not significant. Data were not available on five H x G females and their dams, therefore, a comparison between the reciprocal crosses could not be made* 238 Weight at First Freshening, The data used in this study were body weights obtained shortly after birth of the first calf, of the G x H and H x G crossbreds, and their purebred relatives that calved through September 30, 195>7. Weights were used only for animals that had been born in the herd. Inbred daughters of sires were not included in the daughter averages, nor were they included in the data used to obtain heritability esti mates, however, they were used as dams.. Twins were not included as daughters or dams. Finally, the weights after abortions were not used* Regression of weight on age at first freshening. The weights used were obtained on cows that freshened for the first time at 2 1 to h9 months of age. In order to obtain values to use in adjusting the freshening weights to a common age, linear regression coefficients were calculated according to the method given by Snedecor (1 3 6 ), with weight of the ccut as Y or dependent variable, and age in months as X or independent variable. The regression coefficients for females of the Guernsey and Holstein breeds, and G x H and H x G crossbreds are given in Table $2. In addition the number of cows in each group, average weight and standard deviation, average age in months at calving and standard deviation, the standard error of the regression coeffi cient, degrees of freedom, and t—value are also given. The regression coefficients were all significant at the 5 per cent level or higher. The regression coefficients were rounded off and used to adjust the freshening weights to a common age of 28 months. Table 52 Regression of Weight on Age at First Freshening S, E. of Breed or Average Weight Average Age Regression Regression Degrees of Crossbred Co t s at Calving at Calving Coefficient Coefficient Freedom t-Value (no.) (lb.) (mo.) (no.) Guernsey 298 872.6 + 111.6a 28.93 + 3.3Ua 11.382 1.820 296 6.251* *** Holstein 398 1071.9 + 123.5 28.18 + 3.60 21.iV? 1.356 396 15.597 *** G x H 26 1031.7 + 122.5 27.73 i 2’?8 21.5U0 7.8iil 2ii 2.71*7 ** H x G 16 10U8.3 + 78.6 27.87 + 2.63 15.371 6.766 Hi 2.31*6 * Standard Deviation. # Signified af 5 per cent level (P<0.05). ** Significant at 2.5 per cent level (P<0.025). Significant at 0.1 per cent level (P<0.001), 2U0 Adjustment for Each Month Older Breed or Crossbred or Younger than 28 Months____ (lb.) Guernsey 1 1 . h Holstein 21.1 G x H 21.5 H x G 15.9 The -weights of all animals were adjusted by using the equation given below from Snedecor (136). Adjusted Y Y — bx where Y » weight at freshening b =* regression coefficient x =» deviation of the age of the cow from 28 months, in months. Estimates of heritability of weight at first freshening. The adjusted records of the Guernsey and Holstein cows were used to obtain estimates of heritability of weight at first freshening. The method used was that of intrasire regression of daughter’s weight on dam's weight, then the regression coefficient was doubled to obtain the estimate of heritability. The statistics obtained are given in Table 53o Table 53 Average Weights, Intrasire Regression Coefficients, and Heritability Estimates for Weight at First Freshening Wo. Average Average S. E, of Degrees of Weight Weight Regression Regression of Herit. Breed Pairs Sires Daughters Dams Coefficient Coefficient Freedom t-Value Estimate (no.) (lb.) (lb.) (no.) Guernsey 2i*2 25 861.U 825.8 0.1858 0.0612* 215 3.026 ## 0.372 Holstein 367 15 1069,0 101*0.7 0.1310 0.0581* 350 2.21*3 * 0.262 * Significant at 2,5 per cent level (P^ 0,025)# Significant at 0,5 per cent level (P 4.0,005)# 2k2 Analysis of weights at first freshening of G x H crossbreds. The basic data for the G x H females are given in Appendix Table 27. The data used to calculate H values, and the calculated H values are given in Table 5U. Table 5U Weights at First Freshening of G x H Crossbreds (A), Number and Average of First Freshening Weights of the Paternal Sisters (B), Genetic Values for Dams of the Crossbreds (C), Average Weight at First Freshening of Dams of Paternal Sisters (D), and Calculated H Values Herd No. No. Crossbred Paternal Sire Daughter A Sisters B c D H Holliston 3 958.0 2 691.7 10 )41.7 773. h 132.15 Majesty 7 906.0 7 78U.6 918.0 803.9 6)4.35 Hollibright 52 935.5 29 8U1.3 953.3 807.0 21.05 128 1111.0 29 8U1.3 1059.7 807.0 143.35 Honor 100 1290.0 32 902.3 IIOI4.6 792.1 231.U5 158 95U.O 32 902.3 1088.5 792.1 - 96.50 170 117U.5 32 902.3 9U9.8 792.1 193.35 17 U 1 1 6 )4.5 32 902.3 1102.5 792.1 1 0 7 . 0 0 189 1 2 1 3 . 0 32 902.3 936.2 792.1 238.65 200 993.0 32 902.3 1150.9 792.1 - 8 8 . 7 0 183 1 1 7 1 . 0 32 902.3 9 0 6 . 8 792.1 211.35 Trophy 15U 1099.0 8 926.5 1023.1 871.3 96.60 180 1 0 1 U .0 8 926.5 1003.9 871.3 21.20 19U 981.5 8 926.5 1066.7 871.3 - 142.70 198 93)4.5 8 926.5 10 )48.0 871.3 - 80.35 2U5 1008.0 8 926.5 1106.2 871.3 - 35.95 Main Stay 185 1021.5 12 89)4.1 1228.9 825.6 - 7)4.25 199 1006.5 12 89U.1 1102.8 825.6 - 26.20 Fame 232 106U.5 11 873.3 1030.7 9U8.7 150.20 251 10U3.0 11 873.3 1171.1 9U8.7 58.50 21+3 Table 51+ (continued) Herd No. No. Crossbred Paternal Sire Daughter A Sisters B CD H Raider 21+1 918.0 5 767.8 1136.9 866.3 H+.90 Foremost 21+2 1028.0 8 910.8 91+7.1 850.0 68.65 270 1071+.5 8 910.8 1132.2 850.0 2 2 . 6 0 Hollilier 1+3 998.5 11 850.0 827.2 71+0 .1+ 105.10 2l+ individuals, 10 sires. Sum of positive - negative H values in Table 51+ =* 1,1+35.80 Sum of squares of all H values =» 331,827.9900 Minus correction for sum of squares 3 85,896.7350 Corrected sum of squares =* 2i+5,931*2550 Mean of H - 11+35.80 + 21+ » 59.82 The analysis of variance of the H value is given in Table 55* Table 55 Analysis of variance of H values in Table 51+ Source of Degrees of Sum of Mean variation freedom squares square Total 23 21+5,931.26 sires J? 82,1+68.29 9,163.11+ Within sires ll+ 163,1+62.97 11,675.93 F =* 9,163.11+ * 11,675.93 = 0.78. Not significant. Mean square = 21+5,931.2550 + 23 = 10,692.6632 Variance of mean of H * 10,692.6632 -»■ 2)+ * 1+1+5.5276 , 59.82 59.82 t = ------=, „ 2 .83I+ 1+1+5.5276 21.1075 244 For 23 degrees of freedom the t-value was significant at the 1 per cent leve 1, Analysis of, weights at first freshening of H x G crossbreds. The basic data for the H x G females are given in Appendix: Table 28* The data used to calculate H values, and the calculated H values are given in Table 56. Table 56 Weights at First Freshening of H x G Crossbreds (A), Number and Average of First Freshening Weights of the Paternal Sisters (B ), Genetic Values for Dams of the Crossbreds (C), Average Weight at First Freshening of Dams of Paternal Sisters (D), and Calculated H Values Herd No* No. Crossbred Paternal Sire Daughter A Sisters B C D H Senor 5 1127.7 24 1027.5 844.0 984.3 170.35 6 919.5 24 1027.5 790.2 984.3 - 10.95 Madcap 94 1060.2 31 1093.0 740.5 1019.0 106.45 162 1055.1 31 10 9 3 . 0 911.5 1019.0 15.85 48 1044. 1 31 1093.0 795.1 101 9 . 0 63.05 112 1035.9 31 1093.0 854.6 1019.0 2 5.10 155 1150.3 31 1093.0 926.0 1019.0 103.80 Admiral 114 1087.8 17 1097.8 800.1 1086.4 133.15 Rotarian 225 1122.7 25 1075.8 786.6 1081.0 194.10 Chief 2U6 1092.7 25 1 0 9 6 .u 846.7 1097.7 121.80 Dean 253 992.3 8 1061.2 969.4 1115.5 4.15 JolHy 105 1034.4 42 1110.8 835.0 1037.1 24.65 117 1129.9 42 1110.8 . 916.2 1037.1 79.55 233 1 0 0 4 . 1 42 1110.8 894.4 1037.1 - 35.35 288 945.9 42 1110.8 859.8 1037.1 - 76.25 172 1010.2 42 1110.8 775.6 1037.1 30.15 16 individuals, 7 sires* 2.h& Sura of positive - negative H values in Table 56 * 9U9.60 Sum of squares of all H values 81 llj.1, 266 .3300 2 Minus correction for sum of squares ^ “ 56,358.7600 Corrected sum of squares ** 8U*907.5700 Mean of H » 9k9.60 16 =» 59*35 The analysis of variance of the H values is given in Table 57* Table 57 Analysis of variance of H values in Table 56. Source of Degrees of Sum of Mean variation freedom squares square Total 15 8U,907.57 Sires _6 U6,1*55.73 7,7U2.62 Within sires 9 38,U5l.8U U, 272.1)3 F “ 7 j 7U2.62 + L|,272.I>3 = 1.81. Not significant. Mean square =* 8U,907.57 ♦ 15 =* 5>660.5oU7 Variance of mean of H = 5*660.5ol|7 + 16 = 353*7815 . ^ 59.35 59.35 t 1 . ■ r— ^ = ------** 3.155 V353.7816 18.8091 For 15 degrees of freedom the _t-value was significant at the 1 per cent level. Maternal effects on weights at first freshening of G x H and H x G females. To determine the difference in maternal effects let H-j_ =» H for H x G females, and H2 = H for G x H females* The difference in maternal effects (M^ — Mg) can be estimated as H2 — H]_. Using the means obtained, 2U6 H2 - % 3 £9.82 - ^9.3£ - 0.1-7 The variance of the estimate is the sum of the variances of the two H's which = l4.U5.5276 + 353.7815 3 799.3091 - „ 0.017 >/ 799.3091 23.2721 For 38 degrees of freedom (23 + 15) the t-value was not significant. Test for,, heterosis. The average of \ \ estiHates the heterosis effect unconfounded by maternal effect. Hx + H2 „ 59.35 + 59.82 a 2 2 The variance of this average is ^ (UU5.5276 + 353.7815) “ 199.8273. Applying the t-test, 59.58 59.58 - U.215 v/199.8273 llu 33 60 The t-value was significant at the 0.3. per cent level for 38 degrees of freedom (23 + 15). Discussion. The regression coefficients for weight at first freshening on age ranged .from 21.5UO for the G x H crossbreds to 11.382 for the Guernseys. The coefficients for the G x H females, and Hol- steins were very c3.ose together, while the coefficient for the H x G females was approximately midway between the Guernsey and Holstein breeds. The coefficient from intrasire regression of daughter's weight on dam's weight was higher for the Guernseys than that obtained from the Holstein data. Both coefficients were significant, ( P < 0.005) and (P< 0.025), respectively. These coefficients were a reversal of the trend at l£0, and 180 days for weight. Possibly the Guernsey 2U7 daughters and their dams were affected more by the environment as calves tlian the Holstein daughters and dams* The G x H females averaged 1,0UU.2 + 100.6 pounds, compared to 1,01*0.9 + 100.6 for their Holstein dams. In terms of H they were above the parental mean by 59.62, and the difference was significant (KQ.01). The H x G females averaged 1,050.8 + 66.6 pounds, compared to 833*5 + 76.8 pounds for their Guernsey dams. In terms of H they were 59.35 above the parental mean, and this difference was significant (P<0.01). The H x G females were heavier than the G x H females by 6.6 pounds, but the difference in the mean H values was 0.1?7 In favor of the G x H crossbreds. Using the method employed to test maternal effects this difference was not significant or anywhere near signifi cant. These results indicate that the difference in weight from birth to 6 months of age, between female calves from reciprocal crosses is due to maternal effects, especially a depressing effect of the Guernsey dams. The results indicate that this effect is lost somewhere between 6 and 2 8 months of age. The average of the means of H of the two groups was 59.58, and this difference from the parental means was significant ( F < 0.001). When compared to the parental means the two groups showed heterosis for weight at 28 months of age. SUMMARY AND CONCLUSIONS Data on birth weights, gestation lengths, body weights and heart girth measurements at 90, 150, and 180 days of age, and mammary gland measurements of crossbred and purebred dairy calves were analyzed to determine if the crossbreds showed heterosis. Data on weight at first freshening of females from reciprocal crosses of the Guernsey and Holstein breeds, were compared to purebred animals of these breeds. The criterion for heterosis was that the mean of the data for a group of crossbreds be significantly (P< O.Of?) different from the parental mean. When data on reciprocal crosses were available, maternal effects were removed and the average of the means of the two groups of crossbreds tested for heterosis. Regression coefficients for weight of calf at birth on weight of dam at calving were determined for males, and females of the Brown Swiss, Guernsey, and Holstein breeds and four crossbred combinations. All coefficients were positive except one, which x^as based on a small number of pairs. Regression coefficients for the purebred calves ranged from 0.0232 to 0.0317* and all were significant (P<0.01). The results indicate that under the conditions in the Clemson herd, pure bred calves of the breeds named increase in birth weight two to three pounds for each 100 pound increase in the weight of the dam at calving* Male calves were heavier at birth than female calves in all groups. The differences between males and females were greater in the purebreds than in the crossbred groups* Estimates of the heritability of birth weight were obtained for males and females of the Brown Swiss, Guernsey, and Holstein 2U8 2h9 breeds. Those for Holsteins (females 0.199* males 0.156) were lowest* Guernseys intermediate (females 0.220* males 0.1*30) and the Brown Swiss highest (females 0.789* males 0.5U5)» Estimates of heritability of weight* and heart girth measurement at 90* 150* and 180 days were obtained for Guernseys and Ilolsteins. Intrasire regression coefficients for the Guernseys were positive only for 90 day weights* and heart girths. The heritability estimates were 0.260, and 0.1*56 for weight, and heart girth respectively. Heritability estimates for the Holsteins were 0.219* 0.536* and 0.1*33 for weight* and 0.1*1*1* 0.503* and 0.572 for heart girth at 90* 150* and 180 days. The estimate of the heritability of mammary gland grade in Holsteins was 0.220. The intrasire regression coefficient was negative for Guernseys. Regression coefficients for weight at first freshening on age ranged from 21.51*0 for G x H crossbreds to 11.382 for Guernseys. All coefficients were significant (P<,0.05). The estimates for heritability of weight at first freshening were 0.372 and 0.262 for Guernseys and Holsteins respectively. The G x H females were heavier at birth than the H x G females* and maintained their superiority through 180 days of age. The G x H females also had larger heart girths at 90, 150* and 180 days than the H x G females. The G x H females were significantly heavier than the parental mean for birth weight while the H x G females were not. In terms of H there was a significant (P<0.01) difference between the two groups of 7*17 which was attributed to the maternal effects of the Holstein dams. In testing for heterosis the two means of H were averaged* and the t-value was significant (P<0.01). This indicates 250 that both groups showed heterosis, however, the heterosis was shown by the G x H group* The G x H females were above the parental mean for weight at 90, 100, and 130 days, with the differences significant at 150 (P< There were no weights at 100 days for the H x G group. Maternal effects were not significant at 90 days, but were (P<0.01) at 180 days. The averages of the means of H at 90, and 180 days were tested for heterosis, but the t-values were not significant. The G x H females were above the parental mean for heart girths at 90, 150, 180 days with the differences significant at 150 (P<0.05), and 180 days (P< 0.025)* Sire differences were significant in the 90, and 180 day data. The H x G females were below the parental mean for heart girth at all ages, but the differences were not significant. In terms of H the differences in heart girth between G x H and H x G females at 90, 150, and 180 days were 3.5-5, 2.97, and 6.68 respective ly. The only significant difference was that at 180 days (P<0.02). "When the means of H were averaged there was no evidence of heterosis at any of the ages. The G x H females averaged 1,0UU.2 + 100.6 pounds compared to 1,050.8 + 66.6 pounds for the H x G females at first freshening. In terms of H both groups were above their parental means, and the differences were significant (P £.0.01). The difference between the two groups in terms of H was 0.57 • Using the method to test for maternal effects this difference was not significant. The average of the two means of H was 59*58, which was a significant difference 251 from the parental means (P<,0.00l). The two groups of females showed heterosis for weight at 28 months of age* The G x H females showed heterosis for weight at birth, 150, and 180 days, and for heart girth at 150, and 180 days of age. The Guernsey dams exerted a depressing influence on birth weight, and this influence on size was still apparent at 180 days, but not at 28 months of age. The G x H males averaged 93 .UO + 10.19 pounds, and the mean H value of iuU9 was significantly different (P<0.05) from the parental mean. The H x G males averaged 8 3 .U9 _+ 7.UU pounds, and the mean H value was - l.ijU. The difference from the parental mean was not significant. In terms of H the difference in maternal effects was 7.93, which was significant (P<0.01). When the two means for H were averaged the test for heterosis vjas not significant. The results are similar to those for the females from these reciprocal crosses. The G x H males showed heterosis, whereas the weights of the H x G males were depressed by the Guernsey dams. The S x H females averaged 9.29 in terms of H for birth weight* The t-value was not significant, but it was above the 10 per cent level. These calves did not retain their advantage, as the mean H value was - II4.5U at 150 days, and 0.5U at 180 days. The mean H values for heart girth were - 1.21, and 1.35. None of these values were significantly different from the parental means. The S x H males averaged 6.33 in terms of H above the parental mean for birth weight, and the difference was significant (P<,0.02). The males from this cross showed heterosis for birth weight* The S x G females were slightly above the parental mean for 252 birth weight, but the difference was not significant. At 180 days the average H value was 23.75* and the difference was significant (P<0.01). The conclusion is that heterosis was shown at 180 days. Th3se calves were above the parental mean for heart girth at 180 days, but the difference was not significant. The S x G males were below the parental mean for birth weight, but the difference was not significant. The average gestation length for first born calves was less than the average for second calves in all groups of purebreds except Brown Swiss males. The difference between the gestation lengths of male, and female calves was significant (P<.0.01) in the Brown Swiss, Guernsey and Holstein breeds. The effect of season when the year was divided into two periods, warm and cool was not clear cut. On an intrasire basis there were no significant differences between calves of the same sex born in the two seasons. Estimates of heritability of gestation length were obtained for the Brown Swiss (females 0.292, males 0.637)* Guernsey (females 0.613* males 0.619), Holstein (females 0.339* males 0.U03)* and Jersey (females, 0.318) breeds. All intrasire regression coefficients from which these estimates were obtained were significant (P<^0.01)* except for Brown Swiss females. The G x H females averaged 281*9 + 3 »h9 days, and were - 1.82 in terms of H below the parental mean, but the difference was not significant. The differences between sires were significant (P<.0.0l), therefore, the data were analyzed on a sire basis. The H x G females 253 averaged 280.9 + 3.81 days, and the average H value was - 1.50. The t-value was not significant. The data for both groups were analyzed on a sire basis to determine maternal, and heterosis effects. Maternal effects were not significant, but heterosis effects for a shorter gestation were significant (P<0.02). The G x H males averaged 286.1 + U.33 days, and the mean H value was 2 Jj.7. The difference from the parental mean was signi ficant (P<0.01). The H x G calves had gestation lengths that averaged 280.9 + 3*80 days. The average H value was — 1.76, and the difference from the parental mean m s significant (P<.0.02). The gestation lengths of males were characteristic of those of the breed of sire. Using the test used to test maternal effects the difference between the two groups was significant (P< 0.001). This difference is attributed to the sires, and to genes for gestation length on the Y chromosome. The S x H females averaged ~ $,27 in terms of H below the parental mean. The difference was significant (P^.0.001). The actual average was 280.3 + 3»8ii days, compared to 278.9 + 5.10 days for their dams. The S x H males averaged 28U.Q + 5.75 days for gestation length. The average H value was - 0.70, and the difference from the parental mean was not significant. If there are no differences in maternal effects between Holstein and Brown Swiss cows, the S x H females showed heterosis for a shorter gestation. This could not be determined because data were not available on five H x S females when this study was started. The S x G females averaged - 2.71 in terms of H below the parental mean. The S x G males were also below the parental mean 2$k by - 1.52. The differences were not significant. The H x J females averaged 277.U ± 3.91 days, compared to 280.0 + 3.9U for their Jersey dams. All of the H values were minus, the average being - 3.27, and. it was signifleantly below the parental mean. If there are no differences in maternal effects of Holstein and Jersey cows heterosis was shown. Data on animals from the reciprocal cross (J x H) were not available. Data on nine groups of crossbreds, five female and four male groups -mere analyzed, and all except one (G x . H males) were below the parental mean for gestation length. The estimate of heritability of mammary gland grade at five months of age was 0.220 for Holsteins. The intrasire regression co efficient obtained from the Guernsey data was negative. The G x H females were above the parental mean for mammary gland grade but the difference was not significant. APPENDIX 256 APPENDIX TABLE 1 Birth Weights and Adjusted Birth Weights of G x H Females and their Dams, Adjusted Birth Weights of Maternal Purebred Sisters, Averages of Adjusted Birth Weights of Paternal Sisters of Maternal Sisters and their Dams, and Number of Pairs of Paternal Sisters and Dams Sire Adjusted Average of Adj. and Herd Crossbreds Dams Wts. of Weights of Paternal Number of Adj. A d j . Maternal Sisters, their Dams, Crossbred Birth Birth Birth Birth Purebred Number of Pairs Daughter Weight Weight Weight Weight Sisters Sisters Dams Pairs ------(lb.) Holliston 1 83 90.28 105 1 1 0 .5U none 3 90 93.57 100 97.66 110.08 95.09 9 2 .3k 80 Majesty 7 79 82.U6 90 91.J+8 9U.62 95.13 93.75 25 100.53 95.13 93.75 25 83.72 91.02 93.31 27 86.51 92.50 92.31 8U Knight 18 106 107.60 90 9U.85 86.15 90. 8U 93.12 26 93.22 90. Bit 93.12 26 Hollllier U3 83 86. U6 75 81.01 91 .U2 91.0U 89 .kk i;8 Hollibright 52 77 7k.$k 82 83.72 88.58 92 .U8 9 2.U0 8k Honor 100 10U 101.08 90 86.73 97.22 92.36 92.UU 83 93.1*6 92.36 92.UU 83 93.51 91.00 89.32 h8 89.71 86.53 90.35 2k 99.68 93.08 91.87 16 1U0 80 80.53 91 86.80 95.73 90.96 89.32 U8 96.29 91.15 91.16 12 151 75 7lu63 86 83.15 90.55 91.15 89.53 kl 87.01 91.15 89.53 U7 257 APPENDIX TABLE 1 (continued) Sire Adjusted Average of Adj. and Herd Crossbreds Dams Wts. of Weights of Paternal Number of Adj. Adj. Maternal Sisters, their Dams, Crossbred Birth Birth Birth Birth Purebred Number of Pairs_____ Daughter Weight Weight Weight Weight Sisters Sisters Dams Pairs — UD.l ' Honor (continued) 158 102 101.1+0 81 80.98 87.76 90.66 89.36 1+3 92.68 91.02 89.1+1+ 1+8 170 102 101.86 89 92.1+6 none 183 86 85.?o 77 79.53 95.35 91.1+9 90.23 31 189 93 96.1+6 72 61+.32 95.22 90.97 89.79 1+8 196 76 73.66 82 80.12 89.1+8 90.65 93.23 32 200 82 81+.02 95 96.83 none Trophy 151+ 95 93.82 86 90.38 87.11+ 90.62 89.22 1+7 115.H+ 90.62 89.22 1+7 86.61 86.66 90.20 21+ 156 83 81+.31+ 82 80.58 80.99 91.26 89.1+5 1+8 86.08 90.32 90.02 11+ 180 101+ 102.93 90 88.12 86.30 91.08 85.56 31+ 19it 93 95.99 106 102.50 97.1+2 89.51 88.1+5 H+ 198 78 82.90 83 76.1+8 none 21+5 81+ 88.52 77 79.30 none Main Stay 181+ 79 83.20 112 103.16 none 185 7U 7U.21 101 92.39 lll+,3l+ 88.30 89.17 11+ 199 97 101.31+ 90 87.19 91.61 90.92 85.59 31+ 271 72 70.96 80 77.31 90.17 86.19 87.1+2 1+ Fame 232 92 95.83 89 95.22 none 251 , 93 95.53 101 102.09 none 2$8 APPENDIX TABLE 1 (continued) Sire Adjusted Average of Adj, a nd Herd Crossbreds Dams Wts. of Weights of Paternal Number of I3j7“ Adj. Maternal Sisters, their Dams, Crossbred Birth Birth Birth Birth Purebred Number of Pairs_____ Daughter Weight Weight Weight Weight Sisters Sisters Dams Pairs (1-b.) ------ Foremost 270 82 82.09 90 9^.73 81.92 86.86 89.98 2k 86.1*0 91.08 8$ .3U 3h Number, 28 Average 88.78 88.60 S. D. + 10.31* + 10.07 259 APPENDIX TABLE 2 Birth Weights and Adjusted Birth Weights of H x G Females and their Dams, Adjusted Birth Weights of Maternal Purebred Sisters, Averages of Adjusted Birth Weights of Paternal Sisters of Maternal Sisters and their Dams, and Number of Pairs of Paternal Sisters and Dams Sire Adjusted Average of Adj • and He I'd Crossbreds Dams Wts* of Weights of Paternal N umber of ■ a ------(lb.) Senor 5 72 77.15 95 88.21 78.26 63.72 60.08 10 63.30 66.51 69.39 23 6 82 85.91 62 66.22 none Madcap 18 92 9U.05 83 85.82 87. Ik 69.69 66.11 28 86.33 70.90 72.51 15 70.90 71.73 67.11 39 9l 106 10k.6h 65 71.08 77.01 71.29 67.12 38 82.10 71.29 67.12 38 73.06 70.20 67.37 13 109 81 81.65 70 66.62 79.16 69.98 67.10 28 66.05 70.98 68.96 9 112 78 76.02 58 65.78 70.50 71.71 67.65 39 73.81 70.18 67.13 28 155 86 80.92 72 77.77 66.61 70.70 66.86 13 162 93 88.20 89 82.99 70.75 68.51 71.09 13 177 92 87.6 9 65 70.77 71.37 77.61 65.92 9 Jolly 105 83 81.02 71 81.16 61.08 66.51 69.70 23 71.88 70.15 66.58 28 67.57 70.81 67.31 9 110 70 67.86 56 61.15 70.82 66.01 62.11 1 78.81 68.98 67.59 17 117 91 89.75 65 70.77 71.37 77.61 65.92 9 172 63 60.09 71 68.86 69.77 70.29 66.95 27 71.10 70.29 66.95 27 63.88 71.91 67.58 39 82.50 63.12 60.18 1 56.10 72.90 73.61 15 67.71 71.02 73.95 11 APPENDIX TABLE 2 (continued) Sire Adjusted Average of Adj* and Herd Crossbreds Dams Wts. of Weights of Paternal Number of Adj. Actj . Maternal Sisters, their Dams, Crossbred Birth Birth Birth Birth Purebred Number of Pairs Daughter Weight Weight Weight Weight Sisters Sisters Dams Pairs (lb.) Jolly (continued) 233 75 76.7k 87 82.5U none 239 92 9U.98 86 82.1*0 none 288 73 76.16 71 69.33 none Admiral 111* 78 75.37 62 70.56 73.88 71.65 67.53 39 67.89 71.01 73.83 11* Chief 212 78 8U .20 61 62.58 68.03 69.61 67.51 17 89.03 67.13 72.66 13 2U6 81* 82.51 68 67.57 73.19 69.31 67.22 17 80.65 70.10 7l*.0l* 11* 73.16 68.35 72.27 13 53.68 70.05 79.01 2 2^2 81* 86.57 71* 75.71* none Rotarian 225 90 90.71* 1*8 53.15 77.25 69.88 68.75 13 72.03 71.86 7U.68 15 Dean 253 81* 81.2? 50 1*8.02 51.1*1 70.89 65.69 1* 68.16 71.81 75.70 9 3l*l* 80 76.78 57 58.58 72.05 77.90 67.28 9 Alex 261 APPENDIX TABLE 2 (continued) Sire Adjusted Average of Adj. and Herd Crossbreds Dams Wts. of Weights of Paternal Number of Adj. Adj. Maternal Sisters, their Dams, Crossbred Birth Birth Birth Birth Purebred Number of Pairs Daughter Weight Weight Weight Weight Sisters Sisters Dams Pairs _____ (TV Topnan 332 80 78*17 78 78.81 none Number, 25 Average 82.38 71*01 S. D. + 9*09 + lO.Oii 9 262 APPENDIX TABLE 3 Birth Weights and Adjusted Birth Weights of S x H Females and their Dams, Adjusted Birth Weights of Maternal Purebred Sisters, Averages of Adjusted Birth Weights of Paternal Sisters of Maternal Sisters and their Dams, and Number of Pairs of Paternal Sisters and Dams Sire Adjusted Average of Adj. and Herd Crossbreds Dams Wts. of Weights of paternal Number of Adj. Adj. Maternal Sisters, their Dams, Crossbred Birth Birth Birth Birth Purebred Number of Pairs Daughter Weight Weight Weight Weight Sisters Sisters Dams Fairs — (, -i-D • y Gentleman 255 90 9U.06 90 86.82 none Trusty 260 9h 98.80 72 78.33 none Lucky- 261 98 98.90 90 81.25 none 287 91 9k* 87 110 IOU.97 none Ajax 31U 100 106.80 71 6U.25 none Duke Dan 315 88 9U.80 102 lOlwll 99.62 93.92 91.62 16 Jerry- 37^ 89 86.29 86 88.55 92.1|2 90.10 92.93 18 378 77 81.01 92 88.78 95.12 89.95 92.92 18 380 89 97.65 88 88.02 none Number, 9 Average 9U.80 87.23 S. D. + 7.U8 + 12.1;9 263 APPENDIX TABLE U Birth Weights and Adjusted Birth Weights of S x G Females and their Dams, Adjusted Birth Weights of Maternal Purebred Sisters, Averages of Adjusted Birth Weights of Paternal Sisters of Maternal Sisters and their Dams, and Number of Pairs of Paternal Sisters and Dams Sire Adjusted Average of Adj. and Herd Crossbreds Dams Wts. of Weights of Paternal Number of Adj. Adj. Maternal Sisters, their Dams, Crossbred Birth Birth Birth Birth Purebred Number of Pairs Daughter Weight Weight Weight Weight Sisters Sisters Dams Pairs ~ (lb.) Ajax 283 73 77.3U 66 61.78 7U.26 78.214 72.00 3 370 Ok 8li.?0 6h 66.51 70.01 71.60 73.65 9 Lucky 318 78 83.95 73 69.71 none Duke Dan 320 80 8iw6U 78 68.1k none 321 8U 82.?£ 79 77.95 72.16 68.U3 71.U8 13 Gentleman 32li 70 7k .53 61 62.58 68.03 69.61 67.51 17 89.03 67.13 72.66 13 Number, 6 Average 81.35 67.78 S. D. i k.3U + 5 *86 26k APPENDIX TABLE 5 Birth Weights and Adjusted Birth Weights of G x H Males and their Dams, Adjusted Birth Weights of Maternal purebred Brothers, Averages of Adjusted Birth Weights of Paternal Brothers of Maternal Brothers and their Dams, and Number of Pairs of Paternal Brothers and Dams Sire Adjusted Average of Adj• and Herd Crossbreds Dams Wts. of Weights of Paternal Number of A d j. A dj . Maternal Bros., their Dams, Crossbred Birth Birth Birth Birth Purebred Number of Pairs Son Weight Weight Weight Weight Brothers Bros. Dams j?airs ------(lb.) Holliston 1 92 96.72 110 120.37 10U.60 99.39 96.86 28 Royal Oak 3 102 99.12 113 120 ,k7 none Majesty 7 73 80.73 88 9 7.21 92 .lit 100.53 97.86 73 87.68 100.53 97.86 73 10U.16 100.53 97.86 73 9U.07 91.38 101.23 33 93.21 98.01 98.03 97 90.26 98.01 98.03 97 95.85 98.01 98.03 97 98.31 96.80 96.10 66 90.52 92.25 98.91 11* Hollibright 101* 90 91.21* 86 85.93 none 351 98 100.82 88 91.06 93.10. 95.13 95.89 50 Honor litl 101 95.33 100 107.70 92.56 97.60 93.02 39 IM 110 ioii.52 1*5 51.89 103.1*7 97.23 95.71 17 ll*9 118 117.1*6 96 103.35 lilt.75 91*.07 97.1*9 23 105.21 98.73 95.93 11 97.1*3 97-1*7 93.13 39 87.00 99.33 92.1*7 8 159 102 101.97 9k 96 .1*8 107.36 96.66 96.11 66 100.86 91* .93 97.71* 21* 103.62 97.31 93.31 39 265 APPENDIX TABLE 5 (continued) Sire Adjusted Average of Adj. and Herd Crossbreds Dams Wts. of Weights of Paternal Number of Adj. Adj. Maternal Bros., their dams, Crossbred Birth Birth Birth Birth Purebred Number of Pairs Son Weight Weight Weight Weight Brothers Bros. Dams Pairs (lb.) Honor (continued) 168 87 90.20 7k 86.22 92.76 92.09 99.70 li* 86.95 97.7U 93.57 39 169 83 90.58 86 90.22 86.53 99.53 93.7k 16 17*1 100 103.52 9U 97.06 7U.76 9 7.U7 96.52 U2 113.69 97.05 93.29 39 180 98 108.75 67 76.21 none 182 80 83.07 82 80.30 none Foremost 221 88 80.11 96 98.02 102 .kk 9U.82 95.70 k9 101.2k 9U.82 95.70 k9 101.22 99.09 9 6 .J4.2 11 95 *U5 97.52 93.27 39 238 87 78.79 88 91.06 9 3 .k l 95.13 95.89 50 Main Stay 153 86 90.U7 82 80 . 172 92 9 k .19 92 9U.71 none 177 90 82.0li 96 103.82 85 . I k 99.62 92.89 16 Fame 211 80 8 2 .3J4. 90 90.67 none 222 101 103.50 85 88.18 none 266 APPENDIX TABLE 5 (continued) Sire Adjusted Average of Adj• and Herd Crossbreds Dams Wts. of Weights of Paternal Number o f Adj. Adj . Maternal Bros*, their Dams, Crossbred Birth Birth Birth Birth Purebred Number o f Pairs Son Weight Weight Weight Weight Brothers Pros.' Earns Pairs (lb.) ------ Lucky Lad 322 76 75.21 102 100.68 none Balder 3M* 10U 98.90 100 101.78 none Number, 28 Average 93 .Uo 95.83 S. D. + 10.19 + 15.35 267 APPENDIX TABLE 6 Birth Weights and Adjusted Birth Weights of H x G Males and their Dams, Adjusted Birth Weights of Maternal Purebred Brothers, Averages of Adjusted Birth Weights of Paternal Brothers of Maternal Brothers and their Dams, and Number of pairs of Paternal Brothers and Dams Sire Adjusted Average of Adj. and Herd Crossbreds Dams Wts. of Weights of Paternal Number of Adj. Adj. Maternal Bros., their Dams, Crossbred Birth Birth Birth Birth Purebred Number of Pairs Son Weight Weight Weight Weight Brothers Bros. Dams Pairs — ------(lb.) Senor 4 92 94.81 58 61.20 71.30 69.97 69.97 6 88.32 72.42 68.78 23 Imperial 84 85 85.87 70 71.65 none 86 82 79.97 60 70.80 82.66 74.54 74.12 15 56.95 76.06 75.36 14 Jolly- 85 76 75.42 56 66.18 71.74 79.76 74.54 26 111 86 84.02 60 70.80 82.66 74.54 74.12 15 56.95 76.06 75.36 14 112 82 80.94 58 66.94 64.62 69.30 76.50 26 73.23 74.84 75.06 11 162 91 90.32 60 70.33 64.05 80.52 71.61 43 91.63 73.17 74.75 11 202 88 89.11 81 87.02 none 209 96 93.24 83 83.26 none 230 80 78.36 68 73.06 71*60 75.06 75.12 12 81.61 80.11 71.55 43 239 98 91.42 78 87.25 81.48 74.09 73.21 11 252 69 71.18 78 83.84 none Madcap 160 69 68.66 73 73.57 93.18 81.71 75.38 7 181 94 91.53 83 84.50 84.36 72.71 79.05 7 Chief 164 92 88.64 48 58.18 80.67 71.57 76.23 21 218 98 94.13 100 102.12 none 2 68 APPENDIX TABLE 6 (continued) Sire Adjusted Average of Adj• and Herd Crossbreds Dams Wts. of Weights of Paternal Number of Adj• Adj. Maternal Bros., their Dams, Crossbred Birth Birth Birth Birth Purebred Number of Pairs Son Weight Weight Weight Weight Brothers Bros.DamsPairs (lb.) Chits 2l6 80 80.19 7U 76.1;3 none 282 77 80.63 6I4. 75.01; none Topman 260 73 73.1a 75 78.23 7 9 .U2 71.63 75.27 21 Dean 263 83 83.27 80 79.95 65.55 75*10 75.18 8 Burk 372 78 77.78 72 80.914. none Genius 291* 85 85.63 76 79.39 none Captain 37k 89 81.76 76 79.39 none Number, 23 Average 83.U9 76.52 S. D. + 7.Ull + 9.57 269 APPENDIX TABLE 7 Birth Weights and Adjusted Birth Weights of S x H Males and their Dams, Adjusted Birth Weights of Maternal Purebred Brothers, Averages of Adjusted Birth Weights of Paternal Brothers of Maternal Brothers and their Dams, and Number of Pairs of paternal Brothers and Dams Sire Adjusted Average of Adj• and Herd Crossbreds Dams Wts. of Weights of Paternal Number of Adj. Adj. Maternal Brothers, their dams, Crossbred Birth Birth Birth Birth Purebred Number of Pairs Son Weight Weight Weight Weight Brothers Bros • Dams Pairs Gentleman 231 9h 95.62 109 110.70 none 2 3? 90 9 7 .6)4 86 9U.36 none 237 108 109.05 101* 108.95 116.77 97.59 93.1*9 17 308 120 115*50 90 92.63 none 310 98 102.79 91* 102.80 none 312 72 81; .52 89 99.29 none 325 9h 95.81* 110 110.78 none 379 90 90.73 101* 101.30 none Duke Dan 23h 109 115.09 86 97.21* 91.52 98.73 9U.1*0 39 381* 116 115.78 9h 102.80 none 317 96 99.1U 122 123.01 none 367 103 1 0 2 .1*6 83 91.08 108.01 98.31 9U.55 39 Ajax 296 96 105.98 88 9 0 M none 350 125 123.99 96 102.16 none 366 103 107.53 96 96.31 none 378 106 99.1*1* 101* 108.95 116.77 97.59 93.1*9 17 Lucky- 261 99 101* .01 91* 101* .38 none 330 113 10U.5U 87 92.30 90.10 98.21 97.71* 1*2 352 103 IO6 .7I* 88 90.1*2 none 368 89 97.81 9k 97.28 none 373 10l* 101.56 89 101.82 96.20 98.61 9k .28 39 Number, 21 Average 103.61 100.90 S. D. + 9.13 + 8.32 270 APPENDIX TABLE 8 Birth Weights and Adjusted Birth Weights of S x G Males and their Dams, Adjusted Birth Weights of Maternal Purebred Brothers, Averages of Adjusted Birth Weights of Paternal Brothers of Maternal Brothers and their Dams, and Number of Pairs of Paternal Brothers and Dams Sire Adjusted Average of Adj. and Herd Crossbreds Dams Wts. of Weights of Paternal Number of Adj. Adj. Maternal Bros., their Dams, Crossbred Birth Birth Birth Birth Purebred Number of Pairs Son Weight Weight Weight Weight Brothers Bros. Dams Pairs - (lb.) Lucky 268 80 82.2? 86 6U. 71 none 280 82 83.69 76 7U.09 80.30 73.25 7$ .91 8 289 96 96.92 81* 80 .5U 76.73 6U.77 73.76 6 Gentleman 3U0 78 72.82 79 86.39 76.87 7U.U5 7 3 .3U 18 36U 96 91.06 73 71* .51 86.73 76 .92 1$ .85 11 92.03 79.85 66.19 2 Number, 5 Average 85 «33> 80.11 S. D. + 9.16 + 5.£9 » 271 APPENDIX TABLE 9 Gestation Lengths and Adjusted Gest. Lengths of G x H Females and their Dams, Adjusted Gest. Lengths of Maternal Purebred Sisters, Averages of Adjusted Gestation Lengths of Paternal Sisters of Maternal Sisters and their Dams, and Number of Pairs of Paternal Sisters and Dams Sire Adjusted Average of Adj. Gest. and Herd Crossbreds Dams Gest. of Length of Paternal Number of Gestation Gestalt ion Maternal Sisters, their Dams, Crossbred Length Length Purebred Number of Pairs Daughter Actual Adj• Actual Adj • Sisters Sisters Dams Pairs ------(days) Holliston 1 278 2 7 8 J4 279 279.1; none 2 278 278 J4 281 281.0 276.0 280.1; 279.6 3k 286.0 276.7 279.6 33 3 2?8 278.ii 275 275.0 277.0 278.6 279.0 89 Majesty 7 280 280.0 276 276.0 278.0 2 8 0 .1; 279.9 33 279.0 2 8 0 .1; 279.9 33 276.0 277.0 279.8 33 271.0 276.8 278.8 9k Knight 18 278 278.0 281 281.1; 273.0 277.0 279.5 32 280.0 277.0 279.5 32 Hollilier 1;3 285 285 .U 278 278.1; 283.0 279.2 276.5 53 Hollibright 52 278 278.0 276 276.0 275.0 276.8 278.8 9k 128 27U 27U.0 277 277.0 277.1; 278.6 279.0 89 275.0 279.7 278.1 35 272.0 278.6 277.9 51 Honor 100 282 282.0 275 275.0 2 7 6 .1; 276.8 278.9 93 279.0 276.8 278.9 93 280.0 279.3 276.6 53 277.0 276.3 277.9 21; 272 APPENDIX TABLE 9 (continued) Sire Adjusted Average of Adj. Gest* and Herd Crossbreds Dams Gest. of Lengths of Paternal Number of Gestation Gestation Maternal Sisters, their Dams, Crossbred Length Length Purebred Number of Pairs Daughter Actual Adj• Actual Adj• Sisters Sisters Dams Pairs ------(days) Honor (continued) 283.0 277.9 278.5 18 137 285 285.0 2 8h 28U.lt 275.0 279.lt 276.lt 53 lUo 281* 28U.0 273 273.0 279.lt 279.3 276.6 53 279.0 276.7 279.9 13 151 283 283.0 277 277.0 2 7 6 .O 279.3 276.6 52 282.0 279.3 276.6 52 158 286 286.0 278 2 7 8 .O 278.lt 278.lt 277.8 51 279.0 279.3 276.6 53 170 282 282.0 272 272 *u none 17U 277 277.0 277 277.lt 283.0 279.U 278.1 35 280.0 279.3 276.6 53 283.0 278.3 277.8 51 183 282* 28U.0 2 76 2 7 6 .it 278.0 280.9 279.3 35 189 281 281.0 277 277.0 281. h 279.2 276.6 53 196 281t 28U.O 285 285.0 281.0 279.5 277.9 35 275.0 278.3 278.0 18 200 283 283 .it 28lt 28lt.lt none Trophy 15U 286 286.0 280 280.it 281.0 279.2 276.lt 52 279.0 279.2 276.it 52 280.0 278.lt 277.8 51 276.0 276,3 277.7 2lt 156 282 282.0 273 273.0 272.lt 279.lt 276.6 53 276.0 275.6 279.3 16 180 282 282.0 272 272.0 277.lt 280.6 276.7 37 19U 288 288.it 281 281.0 280.0 275.3 278.8 16 198 283 283.U 279 279.0 none 2it5 283 283.lt 277 277.lt none Main Stay l8lt 279 279.lt 283 283*0 none 185 281 28l.lt 278 278.0 287.0 27U.9 279.0 16 199 281t 28lt.U 275 275.0 277.0 280.6 276.6 37 271 289 289.U 288 288.0 281.0 273.6 278.8 It 273 APPENDIX TABLE 9 (continued) Sire Adjusted Average of Adj. Gest. and Herd Crossbreds Dams Gest. of Lengths of Paternal Number of Ge station Ge station Maternal Sisters, their Dams, Crossbred Length Length Purebred Number of Pairs Daughter Actual Adj • Actual Adj • Sisters Sisiers Dams Pairs (days) Fame 232 280 2 8 0 .1* 2 8 1 281.1* none 2^1 285 285.U 2 8 1 281.0 none Raider 2Ul 279 279.U 27 6 2 7 6 .O none Foremost 270 276 276.0 279 279.1; 272.2* 276.5 277.7 22* 276.0 280.6 276.5 37 Lucky Lad 371 283 283.0 289 289.0 289.0 280.6 278.9 35 Number, 3l* Average 281.9 278.8 S. D. + 3.U9 + 1*.20 27k APPENDIX TABLE 10 Gestation Lengths and Adjusted Gest. Lengths of H x G Females and their Dams, Adjusted Gest. Lengths of Maternal Purebred Sisters, Averages of Adjusted Gestation Lengths of Paternal Sisters of Maternal Sisters and their Dams, and Number of Pairs of Paternal Sisters and Dams Sire Adjusted Average of Adj. Gest, and Herd Crossbreds Dams Gest. of Lengths of Paternal Number of Gestation Gestation Maternal Sisters, their Dams, Crossbred Length Length Purebred Number of Pairs Daughter Actual Adj, Actual Adj Sisters Sisters Dams Pairs ------(days) Senor 5 279 280.7 286 286.0 285.6 286.2 2 8 6 .U 13 277.0 281.5 285.9 25 6 28U 285.7 277 278.7 none Miadeap UB 280 281.7 295 2 9 6 .6 29U.6 28U.3 283.3 35 2 8 9 .0 283.7 2 8 5 .0 18 29 0 .0 28U.O 28U.3 UU 9h 285 285.k 281 282.6 279.7 28U.3 28U.7 U3 281.0 28U.3 28U.7 U3 289.6 286.8 282.9 12 109 282 282.0 288 288.0 27U.7 28U.9 283.5 35 2 8 0 .6 289.3 28U.3 9 112 28U 28U.U 277 278.7 285.7 28U.1 28U.7 UU 2 8 6.6 28U.5 283.8 35 355 28U 28U.il 281 282.7 287.7 287 .0 282.9 12 162 28k 2 8 5 .6 290 290 .U 295.0 28U.3 2 8 5 .6 13 17? 283 283.0 279 279 .U 2 8 9 .6 28 7.2 286.2 8 Jolly 105 283 283.0 28U 28U.U 273.6 281.6 285.9 25 28U.O 28U.6 2 8 3 .6 35 2 7 8 .0 2 8 9 .6 28U.7 9 110 273 273.0 286 286.0 296.6 285.8 279.9 U 286.0 2 8 7 .8 283.2 18 117 282 282 .U 279 279.U 2 8 9 .6 287.2 286.2 8 172 275 275.0 279 2 7 9 .U 278.7 2 8 5 .0 283.9 3U 277.O 285.0 283.9 3U 28U.U 288.9 2 8 1 .6 U 2 7 6 .6 28U.3 28U.7 UU 273.0 28U.6 285.9 18 278.0 280.9 286.7 17 275 APPENDIX TABLE 10 (continued) Sire Adjusted Average of Adj. Gest* and Herd Crossbreds Dams Gest* of Lengths of Paternal Number of Gestation Gestation Maternal Sisters, their Dams, Crossbred Length Length purebred Number of Fairs Daughter Actual Adj• Actual Adj. Sisters Sisters Dams Pairs (days) Jolly (continued) 233 27 6 277.7 283 281*.6 none 239 27t 275.7 281 281.0 none 288 282 283.7 292 292.0 none Admiral lit 27t 27U.0 288 289.7 290 ,li 28l*.0 2 81* .5 1*1* 29t.O 286.3 283.8 12 289 .0 280.2 286.1 17 Chief 212 280 2 8 1 *6 281* 2 8 5 .6 293.7 287 .U 283.2 18 281*.l* 285.1 286.0 13 21*6 277 277*0 278 278.0 2 8 9 .6 267.6 283.7 18 283.lt 2 8 0 .6 286.8 17 2 9 0 .0 281* .6 286.6 13 277.0 2 7 6 .6 281*.7 2 2$2 280 281*7 281 282.6 none Botarian 225 280 280 .0 281 282.7 285.7 2 8 7 .2 282.9 12 281**6 2 8 7 .2 282.9 12 289.it 283.6 285.9 17 Dean 253 280 2 8 0 .0 281 282.7 291.7 287 .0 280.7 1* 2 8 5 .0 286.3 288.8 9 31*1* 285 285.0 290 291.7 288.6 287.U 281**7 8 Alec 280 275 276.7 279 280.7 none 276 APPENDIX TABLE 10 (continued) Sire Adjusted Average of Adj. Gest. and Herd Crossbreds Dams Gest. of Lengths of Paternal Number of Gestation Gestation Maternal Sisters, their Dams, Crossbred Length Length Purebred Number of Pairs____ Daughter Actual Adj, Actual Adj Sisters Sisters Dams Pairs ------(days)---- Topman 332 281 282.6 286 286.0 none Number, 25 Average 280.9 28U.U S. D. + 3.81 + li.8 6 277 APPENDIX TABLE 11 Gestation Lengths and Adjusted Gest. Lengths of S x H Females and their Dams, Adjusted Gest. Lengths of Maternal Purebred Sisters, Averages of Adjusted Gestation Lengths of Paternal Sisters of Maternal Sisters and their Dams, and Number of Pairs of Paternal Sisters and Dams Sire Adjusted Average of Adj. Gest. and Herd Crossbreds Dams Gest. of Lengths of Paternal Number of Gestation Gestation Maternal Sisters, their Dams, Crossbred Length Length Purebred Number of Pairs Daughter Actual Adj• Actual Adj♦ Sisters Sisters Dams Pairs (days) Duke Dan 2$0 281 281 .li 281* 28U.li none 315 279 279 .k 278 278.1; 277.0 278.2 278,3 18 Gentleman 25$ 279 279.U 280 280.0 none Trusty 2 60 279 279.k 275 275.1; none Lucky 261 275 275 .li 268 268.0 none 287 288 288.0 2 8U 28U.0 none £22 * 31i; 281; 281;.U 283 283.0 none Jerry 371; 282 282 .0 283 283.0 2780O 277.5 279.0 19 378 277 277.0 277 277.0 269.U 277.9 279.3 19 380 276 276.U 276 276.0 none Number, 10 Average 280.3 276.9 S. D. + 3.81; + $.10 278 APPENDIX TABLE 12 Gestation Lengths and Adjusted Gest. Lengths of S x G Females and their Dams, Adjusted Gest. Lengths of Maternal Purebred Sisters, Averages of Adjusted Gestation Lengths of Paternal Sisters of Maternal Sisters and their Dams, and Number of Pairs of Paternal Sisters and Dams Sire Adjusted Average of Adj. Gest. and Herd Crossbreds Dams Gest. of Lengths of Paternal Number of Gestation Gestation Maternal Sisters, their Dams, Crossbred Length Length Purebred Number of Pairs Daughter Actual Adj. Actual Adj. Sisters Sisters Dams Pairs — (days) ------ Ajax 283 286 287.7 279 279 .U 28U.6 287.3 287.6 3 370 283 283.0 28U 285.7 28U.7 286.3 288.5 9 Lucky- 318 287 288.7 287 288.6 none 361; 281; 281; .0 28h 28U.O 273.U 283.9 287.5 lit Duke Dan 320 286 287.7 298 298.1; none 321 281* 285.7 287 287.lt 283.6 285.1 285.8 13 Gentleman CO CO CM CM C-U\ 32U 281; 281wO 28U 285.6 293.7 • • 283.2 18 H 28lt.lt 286.0 13 Number, 7 Average 285.8 287.0 S. D. + 2.23 + 5.82 279 APPENDIX TABLE 13 Gestation Lengths of H x J Females and their Dams, Gestation Lengths of Maternal Purebred Sisters, Averages of Gestation Lengths of Paternal Sisters of Maternal Sisters and their Dams, and Number of Pairs of Paternal Sisters and Dams Sire Average of Gestation and Herd Crossbreds Dams Gestation Lengths of Paternal Number of Actual Actual of Maternal Sisters, their Dams, Crossbred Ge station Gestation Purebred Number of Pairs Daughter Length Length Sisters Sisters Dams Pairs ^ day b ) Chief 2U3 281 280 279 275.2 278.5 h 278 280 280 279.il 278.0 Hi 276 276.7 279.2 li 262 281 286 none Jolly 2hh 275 279 286 277.il 278.li 21 Chris 21*8 272 275 none Number, 5 Average 277.il 280.0 S. D. + 3.91 + 3.9U 280 APPENDIX TABLE li* Gestation Lengths and Adjusted Gest. Lengths of G x H Males and their Dams, Adjusted Gest. Lengths of Maternal Purebred Brothers, Averages of Adjusted Gest. Lengths of Paternal Brothers of Maternal Brothers and their Dams, and Number of Pairs of Paternal Brothers and Dams Sire Adjusted Average of Adj. Gest. and Herd Crossbreds Dams Gest. of Lengths of Paternal Number of Gestation Gestation Maternal Brothers, their dams, Crossbred Length Length Purebred Number of Pairs Son Actual Adj• Actual Adj. Brothers Brothers Dams Pairs ------(days) Holliston 1 279 280.7 29h 295.2 282.0 282.2 279.6 31 2 2 8U 285.7 281 282.6 281.0 278.0 281.7 38 Royal Oak 3 282 282.0 283 28U.2 282.0 279.0 280.3 83 Majesty 7 289 290.7 285 286.6 27U.O 279.1 280.1 81 278.0 279.1 280.1 81 285.0 279.1 280.1 81 280.0 278.0 281.6 38 281.0 277.8 280.1 111 277.0 277.8 2 8 0.1 111 279.0 277.8 280.1 111 2 7 6.0 280.3 279.1 68 279.0 279.U 279.5 17 Hollibright io U 28U 285.7 277 278.2 none 151 285 285.0 276 277.6 277.7 279.6 279.5 55 Honor lUl 288 288.0 27 6 277.2 278.0 280.it 279.1 UU lUU 287 287.0 2U8 2U9.2 283.0 281.7 278.9 21 1U9 289 289.0 279 280.6 287.0 279.7 278.6 2k 279.0 275.6 279.9 11 281.0 280.3 279.1 UU 279.0 276.U 276.3 9 359 286 286.0 280 281.2 289.7 280.1 279.2 68 28U.0 280.3 279.1 UU 281 APPENDIX TABLE lit (continued) Sire Adjusted Average of Adj. Gest. and Herd Crossbreds Dams Gest* of Lengths of Paternal Number of Gestation Gestation Maternal Brothers, their Dams, Crossbred Length Length Purebred Number of Pairs Son Actual Adj• Actual Adj. Brothers Brothers Dams Pairs (days) Honor (continued) 168 277 278.7 274 272.6 2 7 2 .0 279.8 2 8 0 .1 17 2 8 1 .0 280.3 279.2 lili 169 278 279.7 277 27 6.2 273.0 2 7 8 .0 281.5 16 17 li 283 28U.7 280 2 8 1 .2 2 7 0 .0 280.8 279.7 hS 278.0 280.lt 279.1 kh 180 280 281.7 278 279.6 none 182 286 287.7 277 2 7 8 .2 none Main Stay 153 290 2 9 0 .0 275 2 7 6 .2 277.0 279.6 279.5 5 5 2 7 8 .0 280.lt 279.2 Itii 171 288 289.7 279 2 8 0 .2 2 7 6 .0 280.6 2 7 9 .8 H5 175 295 296.7 289 2 9 0 .2 2 7 8 .0 277.7 280.7 16 176 289 289.0 282 283.2 283.7 261.7 277.3 21 28li.O 280.5 279.7 U5 281.0 2 7 8 .0 277.9 2 2U9 286 286.0 275 2 7 6 .2 277.0 280 .it 279.2 lili 2 7 8 .0 280.lt 279.2 Itlt 25U 286 287.7 279 280.2 282 .0 281.0 280.5 18 282.0 276.0 276.lt 9 Foremost 221 282 282.0 277 2 7 8 .2 281.7 279.6 279.5 51t 2 7 8.O 2 79.6 279.5 51i 2 7 6 .0 275.9 2 8 0 .1 11 281.0 280.3 279.1 lili 238 283 283.0 276 277.6 277.7 279.6 279.5 55 Trophy 172 28it 285.7 279 280.2 none 177 29lt 295.7 285 286.6 277.0 277.7 280.9 16 282 APPENDIX TABLE I k (continued) Sire Adjusted Average of Adj. Gest. and Herd Crossbreds Dams Gest. of Lengths of Paternal Number of Gestation Gestation Maternal Brothers, their Dams, Crossbred Length Length Purebred Number of Pairs Son Actual Adj. Actual Adj. Brothers Brothers Dams Pairs — (days) ------ Fame 211 281 282.7 280 281.2 none 222 289 290.7 273 27U.2 none 2 ia 285 286.7 278 279*2 273.0 280.5 279.1 1 * Lucky Lad 322 280 280.0 279 280.2 none Raider 31* 285 285*0 282 283.2 none Number, 30 Average 286.1 279.7 S. D. + U.33 + 7.27 283 APPENDIX TABLE 15 Gestation Lengths of H x G Males, Actual and Adjusted Gestation Lengths of their Dams, Gestation Lengths of Maternal Purebred Brothers, Averages of Gestation Lengths of Paternal Brothers of Maternal Brothers and Adjusted Gestation Lengths of their Dams, and Number of Pairs of Paternal Brothers and Dams Sire Av. of Gest. Lengths and Herd Crossbreds Dams Gest. of of Paternal Brothers, Number of Gestation Gestation Maternal Adj. Lengths of their Crossbred Length Length Purebred Dams, Number of Pairs Son Actual Actual Adj • Brothers Brothers Dams Pair6 ------(days) Senor h 286 283 283.9 297 288.1 285.7 7 288 285.5 285.8 31 285 282.8 285.8 30 Imperial 81* 279 288 288.9 none 86 282 277 279.5 286 290.9 281*.9 15 282 289.9 287.1 17 Jolly 85 283 286 286.9 281 283.8 285.6 28 111 278 277 279.5 286 290.9 281*. 9 15 282 289.9 287.1 17 112 281 280 281.3 285 285.6 285.9 31 281* 282.8 285.9 30 288 287.2 285.6 12 162 280 286 286.9 285 285 .8 281*.5 1*6 292 286.8 285.2 12 202 288 289 289.9 none 20? 285 287 287.9 none 230 282 286 287.3 286 288.7 281*. 7 12 281* 285.8 281* .5 1*6 239 282 283 285.5 287 287.2 285.3 12 252 276 286 286.9 none Madcap 160 275 285 285.9 287 281*. 1* 288.5 9 181 286 293 293.9 286 287.1 287.3 8 28H APPENDIX TABLE 15 (continued) Sire Av. of Gest. Lengths and Herd Crossbreds Dams Gest. of of Paternal Brothers, Number of Gestation Gestation Maternal Adj. Lengths of their Crossbred Length Length Purebred Dams, Number of Pairs Son Actual Actual Adj. Brothers Brothers Dams Pairs Chief 16h 285 281 28 3.6 287 281*.? 288.9 22 218 282 288 290.5 none Chris 216 276 277 277.9 none 217 282 288 289.3 290 281*.7 287.5 7 282 271* 283 285.6 none Dean 263 280 290 290.9 283 288.5 285.5 8 32*7 283 286 286.9 288 286.0 2 9 0 .5 2 Genius 291* 283 286 288.5 none Captain 372* 278 286 288.5 none Burk 372 276 281* 286.6 none Number , 22 * Average 280 e 9 286.1* S. D. + 3.80 ■i- 3.86 285 APPENDIX TABLE 16 Gestation Lengths and Adjusted Gest. Lengths of S x H Males and their Dams, Adjusted Gest. Lengths of Maternal Purebred Brothers, Averages of Adjusted Gestation Lengths of Paternal Brothers of Maternal Brothers and their Dans, and Number of Pairs of Paternal Brothers and Dams mrr.'------Sire Adjusted Average of Adj. Gest. and Herd Crossbreds Dams Gest. of Lengths of Paternal Number of Gestation Gestation Maternal Brothers, their Dams, Crossbred Length Length Purebred Number of Pairs Son Actual Adj. Actual Adj• Brothers Brothers Dams Pairs — (days) ------ Gentleman 231 283 2 8 3.0 287 288.2 none 235 279 280.7 283 28U.2 none 23? 280 280.0 279 280.2 280.0 281.9 277.5 21 308 288 288.0 280 281.2 none 310 286 287.7 286 287.2 none 312 266 267.7 280 281.2 none 325 282 282.0 28U 285.2 none 379 275 276.7 277 278.2 none Duke Dan 23U 280 281.7 275 276.6 27^.0 280.5 279.2 lUi 317 285 286.7 285 286.2 none 36? 282 282.0 272 273.6 279.7 280 .U 279*2 bh 381; 289 289.0 286 287.2 none 296 287 288.7 283 28U.2 none 350 296 296.0 282 283.2 none 366 281 281.0 277 278.2 none 378 285 285.0 279 260.2 280.0 281.9 277.5 21 Lucky- 261 281 282.7 285 286.6 none 330 28 9 289.0 283 28U.2 279.0 280.6 279.7 16 352 281; 28U.O 283 281;.2 none 368 290 291.7 276 277.2 none 373 28U 28U.0 281 282.6 283.0 280.3 279.0 Uh 286 APPENDIX TABLE 16 (continued) Sire Adjusted Average of Adj. Gest. and Herd Crossbreds Dams Gest. of Lengths of Paternal Number of Ge station Gestation Maternal Brothers, their Dams, Crossbred Length Length Purebred Number of Pairs Son Actual Adj. Actual Adj• Brothers Brothers Dams Pairs (days) Jerry 279 280.7 279 280.6 none Number, 22 Average 281**0 282.3 S. D. +5*75 + 3.92 287 APPENDIX TABLE 17 Gestation Lengths of S x G Males, Actual and Adjusted Gestation Lengths of their Dams, Gestation Lengths of Maternal Purebred Brothers, Averages of Gestation Lengths of Paternal Brothers of Maternal Brothers and Adjusted Gestation Lengths of their Dams, and Number of Pairs of Paternal B rothere and Dams Sire Av. of Gest. Lengths and Herd Crossbreds Dams Gest. of of Paternal Brothers, Number of Gestation Gestation Maternal Adj. Lengths of their Crossbred Length Length Purebred Dams, Number of Pairs Son Actual Actual Adj. Brothers Brothers Dams Pairs Lucky 268 289 281* 285.3 none 280 286 279 279.9 292 287.1* 286.9 8 28 9 281* 282 282.9 287 285.1 288.1* 7 Gentleman 3k 0 280 278 279.3 276 281*.0 285.9 28 283 285.9 285.2 19 361* 279 280 282.5 286 285.6 286.0 13 287 2 81* *5 281*.2 2 Trusty 365 290 289 289.9 none Number, 6 Average 281*.7 283,3 S . D. + 1**55 + 3.9 0 288 APPENDIX TABLE 18 "Weights at 90, 350 and 180 Days of G x H Females, their Dams and Maternal Purebred Sisters, Averages of Weights of Paternal Sisters of Maternal Sisters and their Dams, Number of Pairs of Paternal Sisters and Dams Wts. of Average Weights of Herd No. Maternal Paternal Sisters, their Crossbred Dams Purebred Dams, Number of Pairs Sire Daughter Weight Weight Sisters Sisters Dams Pairs ------(lb.) --- Weight at 90 Days Honor 170 239.2 211* .0 none 189 21*1 #0 175.0 222.7 236.3 21*1.1 1 200 239.7 209.1 none Main Stay 181* 198.0 195.1* none 189 218.1 19U. 1 265.0 231.9 221.6 5 271 222.3 213.8 none Trophy 191* 220.2 236.0 none 21*5 211.0 218.7 none Fame 232 211*.1 222.7 none 291 191.0 251.1 none Raider 2 1*1 192.9 187.1* none Foremost 21*2 230.0 186.8 none 270 208.8 227.3 229.1* 218.0 230.5 8 Number, 13 Average 217.1* 210.1 S. D. + 17.13 + 21.71* Weight at l90 Days Honor 200 390.0 318.8 none Main Stay 181* 316.3 271**5 none 189 328.8 29i*.6 375.7 315.0 301.5 5 199 312.0 333.8 362.1* 338.1 283.1* 8 Trophy 191* 291.9 329.2 308.2 328.5 291*.6 5 198 30I* .0 289.5 none 2U9 313.5 323.6 none 289 APPENDIX TABLE 18 (continued) Wts. of Average Weights of Herd No. Maternal Paternal Sisters, their Crossbred Dams Purebred Dams, Number of Pairs Sire Daughter Weight Weight Sisters Sisters Dams Pairs (lb.) Weight at 150 Days (continued) Fame 232 308.7 317.8 none 25>1 281.6 311.0 none Raider 2U1 295.0 287.3 none Foremost 2lj.2 318.2 277.3 none 270 311.5 321.9 322.1 317.8 326.2 10 Number, 12 Average 313.7 309.1 S. D. + 20.72 + 23.07 Weight at 180 Days Honor 170 395.0 295.0 none 189 118.5 263.1 371.1 375.6 331.3 1 200 108.5 375.6 none Main Stay 181 375.6 298.0 none 185 367.5 322.8 118.5 373.0 353.9 6 199 383.1 373.0 161.6 101.1 320.2 7 271 381.0 355.5 none Trophy 19k 337.2 361.2 337.1 391.6 317.0 6 198 362.1 338.2 none 215 317.6 365.3 none Fame 232 378.1 371.1 none 251 331.8 399.0 none Raider 210- 311.2 331.6 none Foremost 2k2 395.0 322.1 none Number, Hi Average 373.5 3 H . 3 S. D. + 26.17 + 38.07 290 APPENDIX TABLE 19 Weights at 90 and 180 Days of H x G Females, their Dams and Maternal Purebred Sisters, Averages of Weights of Paternal Sisters of Maternal Sisters and their Dams, Number of Pairs of Paternal Sisters and Dams Wts* of Average Weights of Herd No. Maternal Paternal Sisters, their Crossbred Dams Purebred Dams, Number of Pairs Sire Daughter Weight Weight Sisters Sisters Dams Pairs (lb.) Weight at 90 Days Chief 212 169.6 126.8 12*8.0 169.1* 11*6.3 7 186.7 186.1* 167.5 1* 21*6 201.6 135.5 182.0 161*.5 11*5.0 7 168.7 181* .5 183.7 1* 2£2 191*.6 166.8 none Jolly 233 198.8 193.0 none 239 237.1 169.0 none Topman 332 206.0 191.0 none Madcap 162 217.1 159.9 191. 1* 185.2 159.2 k Number, 7 Average 203.5 163.1 S. D. + 20.71 + 2 5.20 Weight at 180 Days Madcap 162 317.8 269.9 325.0 328.1* 277.8 6 Chief 212 273.5 219.6 27U.7 296.7 21*7.1 7 325.1 328.1* 286.2 6 21*6 35U.8 222.1 281*.l* 295.3 21*6.7 7 280.6 318.9 301.2 7 31*6.6 32l*.8 285.8 6 2£2 370.1 305.9 none Jolly 2 33 339.7 313.6 none 239 387.9 256.3 none Number, 6 Average 31*0.6 26U.6 S. D. + 1*0.82 + 1*0.09 2?1 APPENDIX TABLE 20 Weights at 150 and 180 Days of S x H Females and their Dams Herd No* Crossbred Dans Sire Daughter Weight Weight ----( l b . ) ----- Weight at 150 Days Duke Dan 250 330.0 361.8 315 365.1 361.8 Trusty 260 385.0 323.3 Lucky 261 322.2 356.5 Ajax 311* 367.0 31*0.2 Number, Average 353.9 31*8.7 S. D. + 26.65 + 16.71* Weight at 180 Days Duke Dan 250 383.6 1*20.8 315 1*11.0 396.5 Gentleman 255 1*12.0 386.9 Trusty 260 1*27.9 362.8 Lucky 261 360.7 1*11.1* Ajax 311 1*56.2 380.9 Number, 6 Average 1*13.6 393_.2 S. D. + 21.07 mm+ 35.97 APPENDIX TABLE 21 Weights at 180 Days of S x G Females, their Dams and Maternal Purebred Sisters, Averages of Weights of Paternal Sisters of Maternal Sisters and their Dams, Number of Pairs of Paternal Sisters and Dams Wts, of Average Weights of Herd Ho. Maternal Paternal Sistersi, their Crossbred Darns Purebred Dams, Number of Pairs Sire Daughter Weight Weight Sisters Sisters Dams Pairs ( l b . ) --- Weight at 180 Days Ajax 283 380.2 329.5 none Lucky 318 386.1* 288.9 none 361* 1*01.1 335.0 none Duke Dan 321 1*00.5 310.1* none Gentleman 321* 3li6.6 219.6 2714.7 296.7 21*7.1 7 325.1 328.1* 286.2 6 Number, 5 Average 383.0 292.7 S. D. + 22.21* + lj.3.37 293 APPENDIX TABLE 22 Heart Girths at 90, 15>0 and 180 Days of G x II Females, their Dams and Maternal Purebred Sisters, Averages of Heart Girths of Paternal Sisters of Maternal Sisters and their Dams, Number of Pairs of Paternal Sisters and Dams Heart Average Heart Girth Girth3 of of Paternal Sisters, Herd No. Dams Maternal their Dams, Number Crossbred Heart Heart Purebred of Pairs______Sire Daughter Girth Girth Sisters Sisters Dams Pairs' (cm.) Heart Girth at 90 Days Honor 170 102.5 97-2 none 189 10U 0O 97.9 102.5 106.3 105.7 1 200 110.2 101.1 none Main Stay 181; 97 .5 100.5 none 185 100.9 97.U 105*5 102.8 102.1 5 271 102.3 102.0 none Trophy 19k 103.1 103.5 none 2 b$ 100.8 101.3 none Fame 232 101.3 102 .5 none 251 97.8 107 .8 none Raider 2Ul 98.0 95.0 none Foremost 21*2 103.0 96,2; none 270 100.1 103.0 10U.2 101.0 i o U.i 8 Number, 13 Average 101.6 100 .it S. D. + 3.33 + 3.56 Heart Girth at 150 Days Honor 200 120.0 llli.O none Main Stay 181; 111; .6 110.1 none 185 116.0 115.0 122.5 H 5 .7 113.2 5 199 115 .h 117.9 122.7 119.6 112.9 8 29h APPENDIX TABLE 22 (continued) Heart Average Heart Girth Girths of of Paternal Sisters, Herd No. Dams Maternal their Dams, Number Crossbred Heart Heart Purebred of Pairs Sire Daughter Girth Girth Sisters Sisters Dams Pairs (cm.) Heart Girth at IgO Days (continued) Trophy 19k 113.6 115.5 Hit .5 117.3 113.1 5 198 11U.6 109.6 none 2lt5 11? .5 113.7 none Fame 232 H 5 . 2 115.8 none 251 111.5 121.8 none Raider 2 la 111.5 109.1 none Foremost 2k2 118.7 110.8 none 270 liit.i H 5 . 7 118.5 111* .6 116.3 10 Number, 12 Average 115.1 lUi.i S. D. + 2,1*8 + 3.7U Heart Girth at 180 Days Honor 170 119.0 lilt.3 none 189 125.0 110.7 122.8 121.1 119.3 1 200 12H.5 121.1 none Main Stay 181* 121.8 115.3 none 185 121.8 116.0 127.9 122.3 119.2 6 199 122.3 123.2 131.0 125.9 117.3 7 271 12i*.l 120.5 none Trophy 19U 121.0 121.2 119.5 123.7 ll8.lt 6 198 120.3 116 .1* none 21*5 120.8 119.5 none Fame 232 121.1 122.8 none *51 118.8 128.1 none 2 9$ APPENDIX TABLE 22 (continued) Heart Average Heart Girth Girths of of Paternal Sisters, Herd No. Dams Maternal their Dams, Number Crossbred Heart Heart Purebred of Pairs Sire Daughter Girth Girth Sisters Sisters Dams Pairs Heart Girth at 180 Days (continued) Raider 21*1 117.1 116.3 none Foremost 21*2 123.7 116.3 none Number, ll* Average 121*5 118.7 S. D. + 2.30 + U.U5 APPENDIX TABLE 23 Heart Girths at 90, 350 and 180 Days of H x G Females, their Dams and Maternal Purebred Sisters, Averages of Heart Girths of Paternal Sisters of Maternal Sisters and their Dams, Number of Pairs of Paternal Sisters and Dams Heart Average Heart Girth Girths of of Paternal Sisters, Herd No. Dams Maternal their Dams, Number Crossbred Heart Heart Purebred of Pairs Sire Daughter Girth Girth Sisters Sisters Dams Pairs ( cm.) Heart Girth at 90 Days Chief 212 95.6 86.5 89.9 9U.0 91.1* 7 95.3 97.8 97.2 i* 2U6 101.2 88.3 96.3 93.0 91.2 7 95.0 96.8 96.5 1* 252 96.1* 9l*. 6 none Jolly 233 97.8 97.0 none 239 105.3 96.8 none Topman 332 99.0 98.3 none Madcap 162 101.0 93.U 100.U 96.5 95.5 k Number, 7 Average 99.5 93.6 S. D. + 3.33 + U.53 Heart Girth at 150 Days Chief 212 105.6 98.6 103 .li 108. 3 103.7 5 111.0 110.9 110.3 1* 252 111.5 108.8 none Jolly 233 113.2 109.7 none 239 117 .U 106.5 none 288 113.5 108. h none Number, 5 Average 112.2 1 0 6 .U S. D. + 1*.29 + U.51 297 APPENDIX TABLE 23 (continued) Heart Average Heart Girth Girths of of Paternal Sisters, Herd No. Dams Maternal their Dams, Number Crossbred Heart Heart Purebred of Pairs Sire Daughter Girth Girth Sisters Sisters Danis Fair's (cm.) Heart Girth at 180 Days Madcap 162 113.5 109.6 118.1; 117.2 112.2 Chief 212 112.1 105.0 109.0 11U.3 108.5 11U-7 117.7 112.8 21*6 121.1 107.7 111.9 113.9 108.2 111.0 116.0 lli;.2 120.1 117.0 H2.it 252 118.8 11lw9 none Jolly 233 119.0 lli.ij. none 239 12l*.3 110.3 none 288 117.8 115.2 none Number, 7 Average 118.1 111.0 S. D. + li.20 + 3.9£ 298 APPENDIX TABLE 21* Heart Girths at 15>0 and 180 Days of S z H Females and their Dams Herd No. Crossbred Daughters Dams Sire Daughter Heart Girth Heart Girth ■ (cm.) Heart Girth at 150 Days Duke Dan 250 llU.O 118.0 31$ 119.0 118.0 Trusty- 260 116.6 117.0 Lucky 261 113.6 116.0 Ajax 31h 122.3 117.1* Number,> 5 Averages 117.1 117.3 S. D. + 3.63 + 0.83 Heart Girth at 180 Days Duke Dan 2$0 121.5 121*.7 315 126.5 123.3 Gentleman 2^5 125.6 123 .i* Trusty 260 12U.7 122.6 Lucky 261 117.9 121.9 Ajax 311* 129.1 123.7 Number , 6 Average 121* .2 123.3 S. D. + 12.53 + O .96 2 99 APPENDIX TABLE 25 Heart Girths at 180 Days of S x G Females, their Dams and Maternal Purebred Sisters, Averages of Heart Girths of Paternal Sisters of Maternal Sisters and their Dams, Number of Pairs of Paternal Sisters and Dams Heart Average Heart Girth Girths of of Paternal Sisters, Herd No. Dams Maternal their Dams, Number Crossbred Heart Heart, Purebred of Pairs Sire Daughter Girth Girth Sisters Sisters Dams Pairs Heart. Girth at 1 8 0 Days Ajax 2 8 3 1 2 1 .9 1 1 7 .6 none Lucky 3 1 8 1 2 1 .6 1 1 3 .7 none 36U 1 2 2 .1 1 1 5 .5 none Duke Dan 3 2 1 1 2 1 .3 115.14 none Gentleman 32U 1 1 8 .2 1 0 5 .0 1 0 9 .0 llii.3 108.5 7 H U . 7 117.7 112.8 7 Number, 5 Average 121.0 113 «U S. D. + 1 .6 0 + U .9 2 300 APPENDIX TABLE 26 Mammary Gland Grades and Coded Grades of G x H Crossbreds and their Dams, Coded Grades of their Maternal Purebred Sisters, Averages of Coded Grades of Paternal Sisters to Maternal Sisters and their Dams, Number of Pairs of Paternal Sisters and Dams Sire Coded Average of Coded and Herd Grades of Grades of Paternal Number of Crossbreds Dams Maternal Sisters , their dams, Crossbred Actual Coded Actual Coded Purebred Number of Pairs Daughter Grade Grade Grade Grade Sisters Sisters Dams Pairs Honor 1 58 6 17 h - 10 16 1 6 .2 1 6 .1 ; 5 1 85 6 + 18 5 + 15 15 l6 .h 15 . l i 5 Trophy- 1 80 6 17 5 + 15 1 7 1 5 *2 1 6 .5 8 198 5 H i 6 + 1 8 none Main Stay- 181; 6 - 16 l i + 12 none 185 6 17 i i + 12 17 1 5 .6 1 6 .2 9 1 99 7 - 19 9 26 1 6 15 .ii. 15-1 8 271 5 + 15 5 l i l none Fame 232 5 H i 5 + 15 none 2 5 1 6 - 1 6 6 - 1 6 none Raider 2 l i l 5 + 15 6 - 1 6 none Foremost H 270 5 H i 7 - VO none F 1 Number, 12 Average 16.0 15.7 S. D. + 1.65 + ii.12 301 APPENDIX TABLE 27 Freshening Weights and Adjusted Freshening Weights of G x H Females and their Dams, Adj. Freshening Wts. of Maternal Purebred Sisters, Averages of Adjusted Freshening Weights of Paternal Sisters of Maternal Sisters and their Dams, and Number of Pairs of Paternal Sisters and Dams Sire AdjustedAverage of Adj. and Herd Crossbreds Dams Wts. of Weights of Paternal Number of Adj • Adj. Maternal Sisters, their dams, Crossbred Fresh. Fresh. Fresh. Fresh. Purebred Number of Pairs Daughter Weight Weight Weight Weight Sisters Sisters Dams pairs (lb.) Holliston 3 915 9!? 8.0 1105 102*1.? none Majesty 7 820 906.0 910 888.9 982.2 1025.7 993.0 22 1112.7 1025.7 993.0 22 953.3 966.9 1027.7 19 901* .5 1025.2 1 0 0 2 .2* 61 Hollibright 52 1000 935.5 890 953.3 none 128 H 5 U 1111.0 1100 1057.8 1063.9 1076.3 1082.0 22* 1119.1 1092. 1 1017.7 30 Honor 100 1290 1290.0 1120 1077.8 1220.0 1020.0 999.3 61 1021*.0 1102.5 1086.9 16 158 lOliO 951* .0 111*0 1097.8 nil* .5 1110.7 1035.6 2a 170 1196 1171* .5 992 91*9.8 none 172* 1186 1161* .5 1135 1092.8 1168.1* 1071.9 1080.5 22* 1081*.7 1111.5 1035.7 ia 183 1128 1171.0 1160 906.8 none 189 1170 1213.0 991 91*8.8 1030.7 1112.8 1039.2 2a 200 950 993.0 1172 1150.9 none Trophy 152* 111*2 1099.0 995 1037.2 91*1.8 lllli.O 1037.1 2*0 1152.7 1112*.0 1037.1 2*0 1137.8 1091.5 1018.2* 30 110l*.5 1097.2* 1089.2* 16 180 1012* 101i*.0 1160 991.2 1155.7 1156.3 1067.6 27 302 APPENDIX TABLE 27 (continued) Sire Adjusted Average of Adj. and Herd Crossbreds Dams Wts. of Weights of Paternal Number of Adj. Adj. Maternal Sisters, their Dams, Crossbred Fresh. Fresh. Fresh. Fresh. Purebred Number of Pairs Daughter Weight Weight Weight Weight Sisters Sisters Dams Pairs _ f-ty. Trophy (continued) 19h 960 981.5 1130 1066.7 none 198 870 93k.5 10U8 10U8.0 none 2l;5 965 1008.0 106U 1106.2 none Main Stay 185 1000 1021.5 1250 1228.9 none 199 1200 1006.5 1072 lllU.2 III48.3 1156.5 1063.0 27 Fame 232 1000 1061; .5 10 9h 1030.7 none 251 1000 10U3.0 1150 1171.1 none Raider 2 la 875 918.0 1158 1136.9 none Foremost 2U2 985 1028.0 926 9 k 7 .1 none 270 1010 107U.5 1090 1132.2 none Hollilier U3 1020 998.5 1100 801; .6 1059.1 1112 . 1 10U2.7 la Number, 21; Average IOI4I1..2 10l;0.9 S. D. + 100.6 + 100.6 303 APPENDIX TABLE 28 Freshening Weights and Adjusted Freshening Weights of H x G Females and their Dams, Adj. Freshening Wts. of Maternal Purebred Sisters, Averages of Adjusted Freshening Weights of Paternal Sisters of Maternal Sisters and their Dams, and Number of Pairs of Paternal Sisters and Dams Sire Adjusted Average of Adj. and Herd Crossbreds Dams Wts. of Weights of Paternal Number of Adj. Adj. Maternal Sisters, their Dams, Crossbred Fresh. Fresh. Fresh. Fresh. Purebred Number of Pairs Daughter Weight Weight Weight Weight Sisters Sisters Dams Pairs (lb.) Senor 5 1080 1127.7 830 830.0 830.0 777.0 799.6 6 81I1.6 771.5 780.3 20 6 82iO 919.5 870 790.2 none Madcap U8 1060 lOlOwl 930 759.0 86 7 . 8 8lt0.it 808.7 28 96b .h 900.3 793.2 31 9k 1092 1060 .2 770 758.6 7U2.2 831.0 801.0 5 877.2 903.1 793.2 31 112 1020 1035.9 980 85U.6 none 155 1198 1150.3 1 0 I4.0 926.0 none 162 1 07 1 1055.1 960 91U.U 897.2 903.7 906.7 6 Admiral llii 1056 1087.8 770 781.it 898.6 887.7 886.0 11 Rotarian - - 225 1075 1122.7 730 752.8 999.2 931.0 8U6.7 10 Chief 2U6 10U5 1 0 9 2 .7 862 839.2 892.8 89it.2 82it.it 11 858.8 891.it 880.7 11 917.8 900.3 919.3 6 Dean 253 10U0 992.3 1015 969.ii none 30U APPENDIX TABLE 28 (continued) Sire Adjusted Average of Adj. and Herd Crossbreds Dams WtSo of Weights of Paternal Number of Adj. Adj . Maternal Sisters, their Dams, Crossbred Fresh. Fresh. Fresh. Fresh. Purebred Number of Pairs Daughter Weight Weight Weight Weight Sisters Sisters Dams Pairs (lb.) Jolly 10^ 1098 103k.k 7k0 77k.2 931.6 765.7 783.1 20 892.2 839.5 808.2 28 839.2 875.2 8 7 6 .I k 117 H l b 1129.9 970 92k. k 926.0 89k. 7 803.2 6 172 IOI4.2 1010.2 810 707 .k 75k.k eko.o 81k. k 27 965.2 8 k 0 .0 8lk*k 27 981.6 899.7 79k.8 31 896. k 877.5 780.1 2 868.0 9kk.l 851.3 10 873 .k 890.0 892.7 11 233 1020 lOOli.l 9k0 89k.k none 288 930 9k5.9 8 9k 859.8 none Number, 16 Average 10^0.8 833.5 S. D. + 66.6 + 76.8 LITERATURE CITED 1. ALBERTS, H. W. Report of the Alaska Agr. Expt. Stas., 1930 U. S. Dept. Agr. 16-19. 1931. 2. BAKER, A. L., and QUESEMEERRY, J. R. Comparison of Growth of Hereford and F-. Hereford x Shorthorn Heifers. J. Animal Sci., 3: 322-329. 19UIi. 3* BEADLE, G. W., and COONRADT, V. L. Heterocaryosis in Neurospora crassa. Genetics, 29: 291-308. 19UU. ii. BEARDSLEY, J. P., BRATTON, R. ¥., and SALISBURY, G. W. The Curvilinearity of Heritability of Butterfat Production* J. Dairy Sci., 33: 93-97. 1990. 5* BLACK, V/. H. Beef and Dual-Purpose Cattle Breeding. U. S. Dept. Agr. Yearbook. 863-886. 1936. 6* BONNIER, G. The Sire Index. Acta Agr. Suecana, 1: 321-33U- 19U6. 7. BONNIER, G., HANSSON, A., and SKJERVOLD, H. Studies on Monozygous Cattle Twins IX. The Interplay of Heredity and Environment on Growth and Yield. Acta Agr. Suecana, 3: 1-97* 19ii8. 8. BRAKEL, W. J., RIFE, D. C., and SALISBURY, S. M. Factors Associated with the Duration of Gestation in Dairy Cattle. J. Dairy Sci., 39: 179-19U. 1992. 9« BRIEGER, F. G. The Genetic Basis of Heterosis in Maize. Genetics, 39 s U20-U1+9* 1990. 10. ERUCE, A. B. The Mendelian Theory of Heredity and the Augmentation of Vigor. Science, 32 N.S.: 627-628. 1910. 11. BUZZATI-TRAVERSO, A. A. Heterosis in Population Genetics. Heterosis. Chapter 9« The Iowa State College Press, Ames. 1992. 12. BYCKOV, N. P. Povysenie /irnomolocnosti jzfstfrizskogo $kota. (Increasing the Butterfat Yield of East Friesian Cattle) Sovetsk. Zooteh., 1990 (8). 18-23. 1990 An. Abstracts, 18: 381* 1990. 13* CAMPBELL, M. K., and YAPP, W. W. Findings on Size of Fat Globule in Milk Confirmed. 111. Agr. Expt. Sta., UUth. Annual Report. 129. 1931* 309 306 ill. CARROLL, W. E., and ROBERTS, E. Crossbreeding in Swines Does it Offer an Effective Method for the Improvement of Market Hogs? 111. Agr. Expt. Sta., Bull. U89. 19U2. 15. CARTER, H. W., and HENNING, W. L. The Effect of Heterosis on the Birth Weight of Lambs. J. Animal Sci., 10: 1023-102li. 1951. 16. CASIDA, L. E., and CHAPMAN, A. B. Factors Affecting the Incidence of Cystic Ovaries in a Herd of Holstein Cows. J. Dairy Sci., 3k: 1200-1205. 1951. 17. CASTLE, W. E. Inheritance of Quantity and Quality of Milk Production in Dairy Cattle. Proc. Nat. Acad. Sci., 5s U28-U3U- 1919. 18* CASTLE, W. E, The Explanation of Hybrid Vigor. Proc. Nat. Acad. Sci., 12: 16-19. 1926. 19* CASTLE, W. E. Mammalian Genetics. Harvard University Press, Cambridge, Mass. I9 C0 . 20. CASTLE, W. E., and WRIGHT, S. Studies of Inheritance in Guinea-Pigs and Rats. Carnegie Institution of Washington. Pub. No. 2lilt 3-55. 1916. 21. CHAMBERS, D., and WHATLEY, J. A. Jr. Heterosis in Crosses of Inbred Lines of Duroc Swine. J. Animal Sci., 10: 5o5-£l5>. 1951. 22. COFFMAN, F. A., and DAVIS, L. L. Heterosis or Hybrid Vigor in Oats. J. Am. Soc. Agron., 26: 318-32?• 193k- 23. COLE, L. J. The Wisconsin Experiment in Crossbreeding Cattle. Proc. World's Dairy Congr., 2: 1383-1388. Govt. Printing Office, Washington, D. C. 1921;. 2li. COLE, L. J. The Wisconsin Experiment in Crossbreeding Cattle. Proc. of the Scottish Cattle Breeding Conference, July 192li. Chap. 26. Cattle Ereeding. Oliver and Boyd. Edinburgh• 1925 • 25. COLE, L. J., and JOHANSSON, I. Inheritance in Crosses of Jersey and Holstein-Friesian with Aberdeen-Angus Cattle. Ill Growth and Body Type, Milk Yield and Butterfat Percentage. Am. Naturalist, 82: 265-280. I9I18. 26. COLE, L. J., and JOHANSSON, I. Inheritance in Crosses of Jersey and Holstein-Friesian with Aberdeen-Angus Cattle. I Horns and Shape of Skull. Am* Naturalist, 82: l*l5-170 . 1 9 U8 . 307 27* COLLINS, G. N. Dominance and the Vigor of First Generation Hybrids. Am. Naturalist, 55: 116-133* 1921. 28. COMSTOCK, R. E. Personal Communications of December 6, 1996, . January 2l+, 1957, and November 26, 1997* 29* CROW, J. F. Alternative Hypotheses of Hybrid Vigor. Genetics, 33: 1+77-1+87. 191+8. 30. CROW, J. F. Dominance and Overdominance. Heterosis. Chapter 18. The Iowa State College Press, Ames. 1952. 31* DAVIS, H. P. Influence of Season of the Year and Sire upon the Birth Weight and the Six - and Twelve - Month Gains in Weight For Holstein Females. (Abs.) J. Dairy Sci., hOz 631. 1957. 32. DICKERSON, G. E., LUSH, J. L., and CULBERTSON, C. C. Hybrid Vigor in Single Crosses Between Inbred Lines of Poland China Swine. J. Animal Sci., 5: 16-21+. 191+6. 33* DOBZHANSKY, T. Genetics of Natural Populations. XIX. Origin of Heterosis Through Natural Selection in Populations of Drosophila pseudoobscura. Genetics, 35: 288-302. 1950. 3l+» DOBZHANSKY, T. Nature and Origin of Heterosis. Heterosis. Chapter 13. The Iowa State College Press, Ames"! 1952"” 35* DODGE, B. 0. Heterocaryotic Vigor in Neurospora. Bull. Torrey Bot. Cl., 69: 75-91. 191+2. 36. DUNBAR, R. S. Jr., and HENDERSON, C. R. Heritability of Fertility in Dairy Cattle. (Abs.) J. Dairy Sci., 33: 377. 1950. 37. EAST, C. M. Inbreeding in Corn. Conn. Agr. Expt. Sta., Report for 1907 and 1908. 1+19-1+28. 1908. 38. EAST, E. M. The Distinction Between Development and Heredity in Inbreeding. Am. Naturalist, 1+3: 173-181. 1909. 39. EAST, E. M. Heterosis. Genetics, 21: 375-397* 1936. 1+0• EAST, E. M., and HAYES, H. K. Heterozygosis in Evolution and in Plant Breeding* U. S. Dept. Agr. Bur. Plant Ind. Bull. 21+3* 1912. 1+1# EATON, 0. N. Effect of Crossing Inbred Lines of Guinea Pigs. U. S. Dept. Agr. Tech. Bull. 765» 191+1. 1+2. ELLINGER, T. The Variation and Inheritance of Milk Characters. Proc. Nat. Acad. Sci., 9: 111-116. 1923. 308 1+3* EDLINGER, T.. U. Causes of Variation in Milk Secretion and Their Bearing on Practical Breeding Methods* Proc* World’s Dairy Cong., 2; 1396-lUOl. Govt. Printing Office, Washington* D. C. 1921+. 1+1+. EMERSON, R. A., and EAST, E. M. The Inheritance of Quantitative Characters in Maize. Nebr. Agr. Expt. Sta., Research Bull. 2. 1913. 1+5* FOREMAN, M. H. Some Results of Research on Dairy Cattle Breeding. Proc. 12th. Int. Dairy Congr., Is 656-661. 19i+9* 1+6. FOHRMAN, M. H., McDOWELL, R. E., MATTHEWS, C. A., and KILDER, R. A. A Crossbreeding Experiment with Dairy Cattle. U. S. Dept. Agr. Tech. Bull. 1071+. 195U* 1+7• FREDERICKSEN, L. Foreljzfbige Oplysninger om nogle Fors^g med Malkeleper i Vinteren 1923-21+. Plan for nogle Fors/g med Malkek^fer i Vinteren 1921+-25* (Preliminary Information on Some Experiments with Milk Cows in the Winter of 1923-21+. Plan for some Experiments with Milk Cows in the Winter of 1921+-25.) Meddel. Fors^fgslab. Husdyrbrug. K. Vet. og Landboh^jskole (Denmark), 2. 1925. (Original not read. Cited by Gaines -1+8-) . 1+8. GAINES, W. L. The Energy Basis of 24easuring Milk Yield in Dairy Cows. 111. Agr. Expt. Sta., Bull* 308. 1928. 1+9* GAINES, W. L., and DAVIDSON, F. A. Relation Between Percentage Fat Content and Yield of Milk. Ill* Agr. Expt. Sta., Bull* 21+5. 1923* 50. GASSER, G. W. Progress Report. Uni. Alaska Agr. Expt. Sta., No. 5: 20. 1935. 51. GE0RGES0N, C. C. Report of the Alaska Agr. Expt. Stas., 1925* U. S. Dept. Agr. 17-20. 1927. 52. GERIAUGH, P., KUNKLE, L. E., and RIFE, D. C. Crossbreeding Beef Cattle. Ohio Agr. Expt. Sta*, Research Bull* 703* 1951* 53* GOWEN, J. W. Studies in Inheritance of Certain Characters of Crosses Between Dairy and Beef Breeds of Cattle* J. Agr* Research, 15: 1-58. 1918. 5U* GOWEN, J. W. Inheritance Studies of Color and Horn Characteristics. Maine Agr. Expt. Sta., Bull* 272. 1918* 55* GOWEN, J. W. Inheritance in Crosses of Dairy and Beef Breeds of Cattle* II On the Transmission of Milk Yield to the First Generation. J. Heredity, 11: 300-316. 1920. 309 56. GOWEN, J. W. Inheritance in Crosses of Dairy and Eeef Breeds of Cattle. Ill Transmission of Butter-fat Percentage to the First Generation. J. Heredity, 11: 365-376. 1920. 57« GOWEN, J. W. The Influence of Inheritance and Environment on the Milk Production and Butterfat Percentage of Jersey Cattle. J. Agr. Research, 49: 433-465• 1934. 58* GOWEN, J. W. An Analysis of the Genic or Cytoplasmic Basis of Heterosis. (Abs.) Genetics, 30: 7* 1945* 59• GOWEN, J. V/. Significance of Additive, Dominant, Complementary Gene Action to Hybrid Vigor in Drosophila. (Abs.) Genetics, 31: 217-218. 1946. 60. GOWEN, J. W., STABLER, J., and JOHNSON, L. E. On the Mechanism of Heterosis - The Chromosomal or Cytoplasmic Basis for Heterosis in Drosophila melanogaster. Am. Naturalist, 80: 506-531. 194FT 6 1. GOWEN, J. W. Hybrid Vigor in Drosophiliao Heterosis. Chapter 29. The Iowa State College Press, Ames. 1952. 62. GUSTAFSSON, A. The Effect of Heterozygosity on Variability and Vigour. Hereditas, 32: 263-286. 1946. 63. GUSTAFSSON, A. The Advantageous Effect of Deleterious Mutations. Hereditas, 33: 573-575* 1947 64. HAXES, H. K. Development of the Heterosis Concept. Heterosis. Chapter 3. The Iowa State College Press, Ames. T952. 65. HILDSR, R. A., and FOHRMAN, M. H. Growth of First Generation Crossbred Dairy Calves. J. Agr. Research, 7 8 : 457-469* 1949* 66. H0RLACH3R, L. J. A Comparison of the Growth of Purebred Cheviot and Crossbred Ryeland X Cheviot Lambs. (Abs.) Proc* 26th. Meeting Amer. Soc. Animal Prod., 1 6 3 . 1933* (Original not read. Cited by Miller and Dailey -100-.) 67* HULL, F. H. Recurrent Selection for Specific Combining Ability in Corn* J. Am. Soc. Agron., 37: 134-145* 1945* 68. HULL, F. H. Overdominance and Corn Breeding Where Hybrid Seed is not Feasible. J. Am. Soc. Agron., 38: 1100-1103. 1946. 69* HULL, F. H. Recurrect Selection and Overdominance* Heterosis. Chapter 28. The Iowa State College Press, Ames. 1952. 310 70. JOHANSSON, I. The Heritability of Milk and Butterfat Yield. An. Br. Abstracts, 18: 1-12. 1950. 71. JOHANSSON, I., and HANSSON, A. Causes of Variation in Milk and Butterfat Yield of Dairy cows. K. Lantbr Akad. Handl. (Stockh.), 19y Nr. 6i: 127 p. 19U0. (Original not read. Cited by Johansson -70-.) 72. JONES, D. F. Dominance of Linked Factors as a Means of Account ing for Heterosis. Genetics, 2: 1*66-1*79. 1917* 73. JONES, D. F. The Effects of Inbreeding and Crossbreeding Upon Development. Conn. Agr. Expt. Sta., Bull. 207. ‘ 1918. 7lu JONES, D. F. Heterosis Resulting From Degenerative Changes0 Genetics, 30: 527-51*2. 191*5* 75* JONES, D. F. Plasmagenes and Chromogenes in Heterosis. Heterosis. Chapter ll*. The Iowa State College Press, Ames. 1952. 76. JONES, D. F. Gene Action in Heterosis. Genetics, 1*2: 93-103. 1957. 77. KARPER, R. S. The Effect of a Single Gene Upon Development in the Ileterozygate in Sorghum. J. Heredity, 21: 187-192. 1930. 78. KARPER, R. S., and QUINBY, J. R. Hybrid Vigor in Sorghum. J. Heredity, 28: 83-91. 1937. 79« KEEBLE, F., and PELLEW, C. The Mode of Inheritance of Stature and of Time of Flowering in Peas (Pisum sativum). J. Genetics, 1: 1*7-56. 1910-11. 80. KIRCHNER, W. Uber die Vererbung des Fettgehaltes der Milch beim Rinde. Mitt. Landw. Inst. Univ. Lpz., No. 2: 129-139. 1910. 81. KUHLMAN, A. II. Jersey-Angus Cattle. J. Heredity, 6: 68-72. 1915. 82. LABEN, R. C., and HERMAN, H. A. Genetic Factors Affecting Milk Production in a Selected Holstein-Friesian Herd. Mo. Agr. Expt. Sta., Bull. 1*59. 1950. 83. LAMBERT, ¥. V. Terminology to Describe the Progeny from Various Systems of Breeding. Proc. 33rd. Meeting Amer. Soc. Anim. Prod., 378. 19i*0. 81;. LARSON, C. J., CHAPMAN, A. B., and CASIDA, L. E. Butterfat Production Per Day of Life as a Criterion of Selection in Dairy Cattle. J. Dairy Sci., 3l*: 1163-1169. 1951* 311 85. LEGATES, J. E. Genetic Variation in Services per Conception and Calving Interval in Dairy Cattle. J. Animal Sci., 13: 81-88. 1951*. 86. LIVESAY, E. A. An Experimental Study of Hybrid Vigor or Heterosis in Rats. Genetics, lf>: 17-51** 1930. 87. LUCKWILL, L. C. Studies in the Inheritance of Physiological Characters. IV. Hybrid Vigour in the Tomato. Ann. Bot., H. S. 1: 379-1*08. 1937. 88. LUCKWILL, L. C. Observations on Heterosis in Lycoperslcum. J. Genetics, 3 7 1 1*21-1+1*0. 1938-39. 89- LUSH, J. L. Intra-Sire Correlations or Regressions of Off spring on Dam as a Method of Estimating Heritability of Characteristics. Proc. 33rd. Meeting Amer. Soc. Anim. Prod., 293-301. 191*0. 90. LUSH, J. L. Animal Breeding Plans. 3rd. ed. The Iowa State College Press, Ames'! 19l*5» 91. LUSH, J. L. The Genetics of Populations. Mimeographed Book. 361* p. Copyright by J* L. Lush, June, 191*8. 92. LUSH, J. L. Inheritance of Susceptibility to Mastitis. J. Dairy Sci., 33s 121-125. 1950. 93. LUSH, J. L., NORTON, H. W., and ARNOLD, F. Effects which Selection of Dams May Have on Sire Indexes. J. Dairy Sci., 21*: 695-721. 191+1. 9lw LUSH, J. L., SHEARER, P. S., and CULBERTSON, C. C. Cross breeding Hogs for Pork Production. Iowa Agr. Expt. Sta., Bull. 380. 1939. 95. LUSH, J. L., and SHULTZ, E. N. Heritability of Butterfat Percentage and Butterfat Production in the Bata with which Sires have been Proved in Iowa. (Abs.) J. Dairy Sci., 19s 1*29-1*30. 1936. 96. LUSH, J. L., and STRAUS, F. S. The Heritability of Butterfat Production in Dairy Cattle. J. Dairy Sci., 25: 975-982. 19l*2. 97. MARTIN, T. G. Factors Affecting Birth Weight of Calves in a Crossbreeding Experiment. (Abs.) J. Dairy Sci., 39s 931. 1956. 98. MATHER, K. Dominance and Heterosis. Am. Naturalist, 80: 91-96. 191*6. 312 99. MATHER, K. A Discussion on Hybrid Vigour. Px*oc. Royal Society of London. Series B - Biological Sciences* lltU: 11*3-150. 1955-56. 1 0 0 . MILLER, K. P., and DAILEY, D. L. A Study of Crossbreeding Sheep. J. Animal Sci., 10s 1*62-1*68. 1951* 1 0 1 . MURPHY, R. P. Convergent Improvement With Four Inbred Lines of Corn. J. Am. Soc. Agron., 31*: 138-150. 19l*2. 1 0 2 . NELSON, R. H., and LUSH, J. L. The Effects of Mild Inbreeding on a Herd of Holstein-Friesian Cattle. J. Dairy Sci., 33: 186-193* 1950. 103. OLIVER, C. P., and GREEN, M. M. Heterosis in Compounds of Lozenge Alleles in Drosophila melanogaster. Genetics, 29: 331-31*7. 19UU. 101*. OLSON, T. M. Cross Breeding Experiments. S. Dak. Agr. Expt. Sta., An. Rpt. ll*. 1928. 1 0 5 . OLSON T. M. Crossbreeding. S. Dak. Agr. Expt. Sta., An. Rpt. li*. 1929* 1 0 6 . OLSON, T. M. Cross Breeding Experiment. S. Dak. Agr. Expt. Sta., An. Rpt. 22. 1933. 107. PARLOUR, W. Jersey-Angus Cattle. Live Stk. J. Lond., 77: 85. 1913. 108. PHILLIPS, R. ¥., BLACK, W. H., KNAPP, B. Jr., and CLARK, R. T. Cross-Breeding For Beef Production. J. Animal Sci., 1: 213-220. 191*2. 109. PLUM, M. Causes of Differences in Butterfat Production of Cows in Iowa Cox* Testing Associations. J. Dairy Sci*, 18: 811-825. 1935. 1 1 0 . POWERS, L. Inheritance of Quantitative Characters in Crosses Involving Two Species of Lycopersicon. J. Agr* Research, 63: ll*9-17U. 191*1. 111. POWERS, L. An Expansion of Jones's Theory for the Explanation of Heterosis. Am. Naturalist, 78: 275-280. 19UU* 1 1 2 . POWERS, L. Gene Recombinations and Heterosis. Heterosis. Chapter 19. The Iowa State College Press, Ames. 1952• 113* PRENTICE, E. P. Mount Hope and Its Dairy Cattle. Agr. Hist., 20* 193-209. 191*6. 313 ill*. QUINBY, J. R., and KARPER, R. E. Heterosis in Sorghum Resulting from the Heterozygous Condition of a Single Gene that Affects Duration of Growth. Am. J. Bot., 33: 716-721. 191*6. 115. RALSTON, N. P., MEAD, S. W., and REGAN, V/. M. Preliminary Results from the Crossing of Two Inbred Lines of Hoisteins on Growth and Milk Production. (Abs.) J. Dairy Sci., 31* 657-658. 191*8. 1 1 6 . RANDOLPH, L. F. The Influence of Heterozygosis on Fertility and Vigor in Autotetraploid Maize. (Abse) Genetics, 27: 163. 191*2. 117. RASMUSSON, J. A Contribution to the Theory of Quantitative Character Inheritance. Hereditas, 18: 2l*5-26l. 1933-3U. 118. REGAN, W. M. Crossbreeding Within the Breed. Guernsey Breeders' Journal, 70: 705-707, 916. 191*6. 119. RICHEY, F. D., and SPRAGUE, G. F. Experiments on Hybrid Vigor and Convergent Improvement in Corn. U. S* Dept. Agr* Tech. Bull. 267. 1931. 120. RICHEY, F. D. Hybrid Vigor and Corn Breeding. J. Am. Soc. Agron., 38: 833-81*1. 191*6. 1 2 1 . RICHEY, F. D. Corn Breeding. Advances in Genetics, 3: 159-192. Academic Press, New York, N. Y. 1950. 122. ROBBINS, W. J. Growth of Excised Roots and Heterosis in Tomato. Am. J. Bot., 28: 216-225. 19l*l. 123. ROBERTS, E., and CARROLL, W. E. A Study of Hybrid Vigor in a Cross Between Poland China and Duroc Jersey Swine. J. Agr. Research, 59: 81*7-851*. 1939* 121*. ROBERTSON, A. Crossbreeding Experiments with Dairy Cattle* An. Br. Abstracts, 17: 201-208. 19l*9. 125. ROLLINS, V/. C., LABEN, R. C., and MEAD, S. V. Gestation Length in an Inbred Jersey Herd. J. Dairy Sci., 39: 1578-1593. 1956. 126. SCHMIDT, J. Die bisherigen Ergebnisse und die zukunftige Gestaltung der Rinder-Kreuzungsversuche des Kaiser- Wilhelm-Instituts fur Tierzuchtforschung* (Previous Results and Future Form of the Cattle Crossing Experiments at the Kaiser Wilhelm Institute for Animal Breeding Research). Mitt. Landw. (Berl.), 59: 776-777. 191*1*. 311+ 127*' SCHMIDT, J. Scirwarzburite Niederungs-Kuhe und Jersey-Bullen. Kreuzungsversnche -und. i h r e Auswertung. (Black Pied Lowland Cows sxid J e r s e y B u l l s . Crossing Experiments and their Evaluation.) Z u c h t u n g s k u n d e , 20: 29-39. 191+8. 128. SHULL, G. H. Tine Composition, o f a Field of Maize. Rep. Am. Br. Ass., 1+: 296-301* 1908. 129. SHULL, G. H. H ^ r b r i d i z a t i o n M e t h o d s In Corn Breeding. Am. Br. Mag., Is 98-107. 1910. 130. SHULL, C-. K. Tixe G e n o t y p e s of* Maize. Am. Naturalist, 1+5: 231+-252. 19ID. • 131. SHULL, G. H. ‘Draplicate Genes for Capsule Form in Bursa bursa-p-a.storis. Zeits. Ind. Abst. Ver. 12: 97-li+9"^ l^lli- • ( O r i g i n a l not read. Cited by Shull -132-.) 132. SHULL, G. H. Wliat Is ,fHeterosis”? Genetics, 33: 1+39-1+1+6. 191+-8. 133. SIERK, C. F., a n d W I N T E R S , 1. M. A Study of Heterosis in Swine. J. A n i m a l Sci., 10: 101+-111. 1951* 13U. SINGLETON, W. R • B r e e d i n g E e h a v i o r of C 30 a Diminutive P 39 Mutant IVInose H y b r i d s S h o w Increased Vigor. (Abs.) Genetics, 2 8 s 89* 191+3. 135. SMITH, A. D. B U C H A N A N . I n h e r i t a n c e of Milking Capacity in Dairy Cattle . J. F a r m e r s 1 Club), (Lond.) , 191+8(7): 86-91. Discxassion: 91—98. 191+8. 136. SNEDECOR, C*. W * S t a t i s t i c a l Me t h o d s . 1+th. ed. The Iowa State College Press, Ames". 191+6. 137. SNEDECOR, G. W. S t a t i s t i c a l Me t h o d s . 5th. ed. The Iowa State College Press, Ames. 1956. 138. SPRAGUE, G. F. The P r o b l e m of Heterosis. Chronica Botanica, 7: 1418-1+19. J-91+3. 139. STADLER, L. J- Some Observations on Gene Variability and Spontaneous M u t a t i o n . S p r a g g Memorial Lectures, Michigan State College * 1 —15 . 1939. (Original not read. Cited by Crow -30- . } 1U0. STALLCUP, 0. T . , HORTON, O. H., a n d BROWN, C. J. The Duration of G - ^ s t a t i o n i n D a i r y Cattle. Ark. Agr. Expt. Sta., Bull. 5 7 6 . 1 9 5 6 . 315 11*1 * STRAUS, F. S., and GOWEN, J. W. Heterosis: Its Mechanism in Terms of Chromosome Units in Egg production of Drosophila melanogaster» (Abs.) Genetics, 28: 93* 19k3* l1*2. STUEBE, H., and PIRSCHLE, K. Uber Sinen Monogen Bedingten Fall von Heterosis bei Antirrhinum majus. Ber. Deutsch. Bot. Ges., 58: 5U6. 19lEU (Original not read. Cited by Gustafsson -62- and Winters -157 — .) 11*3. SWETT, W. W. A Cow a Calf Will Be. Tbe Yearbook of Agricul ture, 191*3-191*7 • 195-200. Govt. Printing Office, Washington, D. C. 19l*7 • 11*1*. THOMPSON, N. R., CRANEK, L J. Sr., and RALSTON, N. P. Genetic and Environmental Factors in the Development of the American Red Danish Cattle. J . Dairy Sci., 1*0: 56-66. 1957. ll*5. TQUCHBERRY, R. W. Genetic Correlation^ Between Five Body Measurements, Weight, Type, and Product Lon in the Same Individual Among Holstein Cows. J. Hairy Sci., 3hi 21*2-255. 1551. 11*6 . TOUCHBERRY, R. W., and TABLER, K. A. Variations in the Birth Weights of Purebred and Crossbred Holstein and Guernsey Calves. (Abs.) J. Animal Sci*, 13: 961*• 1951*. 1U7. TYLER, W. J., CHAPMAN, A. B., and DICRH:I£0N, G. E. Sources of Variation in the Birth Weight of Holstein-Friesian Calves. J* Dairy Sci*, 30 1 1*83-1*98. 19l*7« 11*8 . TYLER, W. J., and HYATT, G. Jr. The Heritability of Milk and Butterfat Production and Percentage of Butterfat in Ayrshire Cattle. (Abs.) J. Animal Sc::.*, 6: 1*79-1*80. 191*7 • ll*9. TYLER, W. J., and HYATT, G. Jr. The Heritability of Official Type Ratings and the Correlation Eet/ween Type Ratings and Butterfat Production of Ayrshire Cou/£. J* Dairy Sci., 31s 63-70. 191*8. 150. TYLER, W. J., HYATT, G. Jr., CHAPMAN, A. B., and DICKERSON, G. E. The Heritability c?f Body Size of Holstein- Friesian and Ayrshire Cattle. (Abs.-) J* Animal Sci., 7: 516. 191*8. 151. WHALEY, W. G. Physiology of Gene Acti-on in Hybrids. Heterosis. Chapter 6. The Iowa St^te College Press, Ames. 1952. 152. WHITE* W. T. Report of the Alaska Agl*. Expt. Stas., 1931* and 1932. U. S. Dept. Agr. 19-20. 1933. 316 153* WHITE, W. T. Eirth-Weight, Gestation Period, and Sex Ratio of Alaskan Hybrid Holstein-Galloway Calves. J. Dairy Sci., 17: 709-716. 1931*. 151*. WHITE, W. T., and IBSEN, H. L. Color Inheritance in Galloway Holstein Crosses. J. Heredity, 26: 75-81*. 1935. 155. WILCOX, C. J., PFAU, K. 0., and BARTLETT, J. V/. An Investigation of the Inheritance of Female Reproductive Performance and Longevity, and their Interrelationships Within a Holstein-Friesian Herd. J. Dairy Sci., 1*0: 91*2-91*7. 1957. 156. WILSON, J. W. A Cross-Breeding Experiment. S. Dak. Agr. Expt. Sta., An. Rpt. 9. 1925* 157. WINTERS, L. M. Animal Breeding 5th. ed. John Wiley and Sons. New York. 1951*. 158. WINTERS, L. M., JORDAN, P. S., HODGSON, R. E., KISER, 0. M., and GREEN, W. W. Preliminary Report on Crossing of Inbred Lines of Swine. J. Animal Sci., 3: 371-379* 191*1*. 159. WINTERS, L. M., KISER, 0. M., JORDAN, P. S., and PETERS, W. H. A Six Years’ Study of Crossbreeding Swine. Minn. Agr. Expt. Sta., Bull. 320. 1935. 1 6 0 . WOODWARD, T. E., and GRAVES, R. R. Results of Inbreeding Grade Holstejn-Friesian Cattle. U. S. Dept. Agr. Tech. Bull. 927. 191*6. 1 6 1 . WRIGHT, S. The Effects of Inbreeding and Crossbreeding on Guinea Pigs. III. Crosses Between Highly Inbred Families. U. S. Dept. Agr. Bull. 1121. 1922. 162. YAPP, W. W. The Inheritance of Per Cent Fat Content and other Constituents of Milk in Dairy Cattle. Proc. of the Scottish Cattle Breeding Conference, July, 1921*- Chap 27. Cattle Breeding. Oliver and Boyd. Edinburgh. 1925* 163. YAPP, W. W. Crossbred Herd Supplies Important Facts on Inheritance. 111. Agr. Expt. Sta., 1*2 »d An. Rpt. 123-125. 1929. 161*. YAPP, W. W. Scientific Breeding Advanced try Inheritance Studies. 111. Agr. Expt. Sta., l*l*th. An. Rpt. 123-121*. 1931. AUTOBIOGRAPHY I, - William Brandt, was born in Pittsfield Township, Lorain Co^ Ohio, August 21, 1911. I received my elementary training V' Pittsfield Township Schools and graduated from Wellington School. I received my undergraduate training at The Ohio S ' Jniversity, which granted me the Bachelor of Science degree in ! ffrom the University of Nebraska I received the < Master of ‘ ce degree in 1938. While in residence there, I was an Assist3' the Dairy Husbandry Department. In September, 1937? ( I was appn- - American Guernsey Cattle Club Fellow in the Department animal Husbandry, The Ohio State University. On July 1, 1938, i ■ appointed Instructor in the Department of Animal Husbandry* eft this position in June 19Ul for commercial work. I was app3 : Instructor in the Animal Husbandry Department, Cornell it’" ' uity in April, 19^4.. In May, 19u8, I was appointed Agent in ' ireau of Dairy Industry. TJ. S. D. A. and Associate Dairy Hus1 ^ an in the Dairy Department, Clemson Agricultural College. ve been at the Clemson Agricultural College since May, I9bt> - now hold the position of Associate Professor and Associate ■y Husbandman# 317