THE EFFECT OF GESTATION ON MILK AND

BUTTEKFAT PRODUCTION IN DAIRY

CATTLE

DISSERTATION

Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University

By

WILLIAM MATHIAS ETGEN, B. S., M. S.

The Ohio State University 1958

Approved by

Adviser Department of Dairy Science ACKNOWLEDGMENTS

I wish to express my sincere appreciation to my adviser and friend, Dr. Thomas M. Ludwick, Professor in the Department of

Dairy Science, Ohio State University, and Project Leader of the

Ohio NC-2 Dairy Cattle Breeding Project. I am greatly indebted to Dr. Ludwick for the inspiration, time, guidance, and technical assistance in planning this project and editing the manuscript.

My sincere thanks are expressed to Dr. Fordyce Ely, Chair­ man of the Department of Dairy Science, Ohio State University, for his interest in this project and for his help in editing the manuscript.

To Dr. George R. Johnson, Chairman of the Department of

Animal Science, Ohio State University, I extend my thanks for his reading of the manuscript.

I wish to express my appreciation to Dr. D. Ransom Whitney,

Professor in the Department of Mathematics and Director of the

Statistics Laboratory, Ohio State University, for his assistance in the statistical analysis of this project.

Also, I am greatly indebted to Herman Rickard, Earl Rader,

Don Richardson, Ervin Akins, Dr. Edwin Hess, Harry Barr, Dr.

Harry Donoho, and Dr. C. M. Clifton. These persons have given unsparingly of their time and efforts in all phases of the study.

ii CONTENTS

PAGE

INTRODUCTION...... 1

REVIEW OF LITERATURE...... 3 Effect of Gestation on Production ...... 3 Other Factors Affecting Production ...... 9 Production Record Evaluation ...... 12 Physiological Aspects of the Effect of Gestation on Lactation ...... l4

MATERIALS AND M E T H O D S ...... 19

RESULTS AND DISCUSSION ...... 26

SUMMARY AND C O N C L U S I O N S ...... 4?

LITERATURE CITED ...... 49

APPENDIX...... 55

AUTOBIOGRAPHY ...... 94 TABLES

TABLE PAGE

1 AGE-CONVERSION FACTORS ...... 21

2 SUMMARY OF THE MULTIPLE REGRESSION ANALYSIS OF MILK AND BUTTERFAT PRODUCTION WITH DAYS OPEN IN HOLSTEIN COWS (1,508 OBSERVATIONS) ...... 28

3 SUMMARY OF THE MULTIPLE REGRESSION ANALYSIS OF MILK AND BUTTERFAT PRODUCTION WITH DAYS OPEN IN TWO-YEAR-OLD HOLSTEIN COWS (680 OBSERVATIONS) . . 30

4 SUMMARY OF THE MULTIPLE REGRESSION ANALYSIS OF MILK AND BUTTERFAT PRODUCTION WITH DAYS OPEN IN THREE- AND FOUR-YEAR-OLD HOLSTEIN COY/S (480 OBSERVATIONS)...... 31

5 SUMMARY OF THE MULTIPLE REGRESSION ANALYSIS OF MILK AND BUTTERFAT PRODUCTION WITH DAYS OPEN IN FIVE-YEAR-OLD OR OVER HOLSTEIN COWS (348 OBSERVATIONS) ...... 33

6 SUMMARY OF MULTIPLE REGRESSION COEFFICIENTS AND CALCULATED DIFFERENCES IN PRODUCTION DUE TO DAYS OPEN BETWEEN THOSE COWS CONCEIVING 85 DAYS AFTER FRESHENING AND THOSE NOT CONCEIVING DURING THE 305 DAY LACTATION ...... 37

7 FACTORS TO CORRECT FOR INFLUENCE OF GESTATION ON PRODUCTION OF HOLSTEIN COWS (ALL A G E S ) ...... 4l

8 FACTORS TO CORRECT FOR INFLUENCE OF GESTATION ON PRODUCTION OF HOLSTEIN COWS (TWO-YEAR-OLDS). . . . 42

9 FACTORS TO CORRECT FOR INFLUENCE OF GESTATION ON PRODUCTION OF HOLSTEIN COWS (THREE- AND FOUR- YEAR-OLDS) ...... 43

10 FACTORS TO CORRECT FOR INFLUENCE OF GESTATION ON PRODUCTION OF HOLSTEIN COWS (FIVE-YEARS-OLD OR OVER) ...... 44

11 ORIGINAL DATA FROM THE LONDON H E R D ...... 56

12 ORIGINAL DATA FROM THE TOLEDO H E R D ...... 76

iv ILLUSTRATIONS

FIGURE PAGE

1 Regressions of milk production on days o p e n ...... 35

2 Regressions of butterfat production on days o p e n ...... 36

v INTRODUCTION

Production records of dairy cows are influenced by many variable factors. Some of these are age, live weight, number of times milked daily, length of lactation period, level of nu­ trition, housing conditions, care, previous calving interval, previous dry period, and length of gestation. Numerous attempts have been made by many investigators to correct for these vari­ able factors that have had an influence on the amount of milk and butterfat produced during a lactation. Some of these correction factors are in general use today. The factors developed by the

United States Department of Agriculture (51,32,33) to correct production records to a standardized 2X, 305 day, mature equiva­ lent basis are valuable in correcting for age differences, for differences in the number of times a cow is milked daily and for differences in the length of the lactation period.

It has been thought by many that the number of days a cow is pregnant during her lactation may have considerable influence on the amount of milk and butterfat she produces during that lac­ tation. Several investigators (14,23,24,26,28,29,52,53,55) have shown that a definite inhibitory effect of gestation on lactation exists. However, most of these investigations were conducted before the standardized 305 day mature equivalent factors were adopted. Because of the lack of standardization in these 2

studies, there was considerable variation in the length of lac­

tation that was considered. In some of the studies, allowances

were made for age, and in others, age differences were not

considered.

There is a wide difference of opinion concerning the amount

of variation in production due to gestation. Some investigators

feel that the effect is considerable (as great as 2,500 pounds

of milk), while others feel there is very little effect (200-500

pounds of milk).

A study conducted under standardized conditions, and de­

signed to measure the effect of gestation on production should

be of value to researchers in evaluating production records.

This study should also be valuable to farmers and dairymen in

analyzing production records of cows in their own herds and

records of cows in other herds, from which they plan to purchase breeding stock.

The object of this study is to determine the effect of

gestation on milk and butterfat production in Holstein-Friesian cattle. REVIEW OF LITERATURE

Effect of Gestation on Production

The thought that the interval of time which a cow carried a calf during lactation might have some effect on the amount of milk and butterfat she produced is not a new one. As early as

1913, Gavin (26) studied the effect that time of service might have on daily milk yield. He found that the rate of decline in production seemed to increase 16 to 20 weeks following service.

He also concluded from his investigation that longer periods of gestation definitely lowered the cow's annual production.

Soon after this work was published, Eckles (1^) conducted a study to determine the amount of nutrients required to develop a bovine fetus. He concluded that the nutrients required to develop a Jersey calf were equivalent to approximately 110 to 170 pounds of Jersey milk and those required for a Holstein calf were equiva­ lent to approximately 200 to 275 pounds of Holstein milk.

Brody et al. ( k ), in 1923, studied the effect of gestation on production and body weight in Guernsey and Jersey cows. In this study, they divided the production records into two groups, those records from cows which conceived during the third and fourth month of lactation and those which did not conceive during the lactation. They reported that the level of production de­ creased rapidly in the pregnant cows after the third or fourth 4 month of lactation. The pregnant cows averaged approximately 450 pounds less milk per lactation than the non-pregnant ones. These workers also reported that the pregnant cows' body weight started increasing about the same time that the rapid decline in pro­ duction occurred.

Sanders (52) correlated service period and lactation pro­ duction (using the total lactation as long as 500 days) and derived factors to correct for the effect of gestation on pro­ duction. His factors varied from + 22 percent for production records from cows bred back in less than 20 days to - 35 percent for production of cows that were open from 480 to 499 days.

Hammond and Sanders (29) analyzed the production records of

1,410 cows of eight breeds from four herds in England in an effort to determine the effect of gestation on production. They divided the animals into groups according to their service periods (the time between freshening and rebreeding) by 20 day intervals (0-19, 20-39, etc.) and averaged the production records of each of these groups. They found a correlation of .33 between service period and total milk yield. They also concluded that the association of service period and total milk yield was not linear. The level of production seemed to rise more rapidly when the service period was very short and then tended to level out somewhat as the service period grew longer. Correction factors were calculated using 100 days as a standard service period.

These factas ranged from + 30 percent for animals with less than a 20 day service period to - 28 percent for those animals with a

service period from 480 to 499 days.

In 1924, Ragsdale et al. (49) studied Advanced Registry Pro­

duction records of Guernsey cows, using yearly milk production

as a measure of productivity. They divided the records into two

groups, those records from cows bred back in the third or fourth

month of lactation and those which did not conceive during the

year’s production. They found no difference in the two groups

in the first five months production, but they observed that the

production of the pregnant cows declined more rapidly than the

non-pregnant cows after the fifth month of lactation. From their

work, they estimated that gestation caused a reduction of 480 to

800 pounds of milk per 12 month lactation in Guernsey cattle.

Sanders (55)i in 1928, analyzed 3*918 lactations from four

breeds of cattle in England. He divided the lactations into two

groups: first lactations, and not first lactations. The records

were then divided into groups with service periods of 20 day

intervals. The regression coefficient of service period on

total lactation yield was calculated. The coefficient was .40

and indicated a significant association between service period and total lactation production. The regression line was tested

for linearity, and it was found to be not linear. He then calculated a curvilinear line and derived correction factors

from this line using an 85 day service period as the standard. 6

A brief summary of these correction factors is given below:

Correction Factors

■vice Period First Lactation Others

of /O %

0-19 28.2 33.9

20-39 18.4 21.3

40-59 10.6 11.9

60-79 4.2 4.6

80-99 -1.1 -1.1

100-119 -5.5 -5.9

120-139 -9.2 -9.7

140-159 -12.4 -12.9

160-179 -15.2 -13.5

180-199 -17.6 -17.8

280-299 -25.8 -25.1

480-499 -33.3 -30.8

A study was also conducted to determine whether there were breed differences or whether there were differences between high and low yielders. He could find no significant differences in either case.

Gowen (28) used Advanced Registry Guernsey records to conduct a study of the effect of gestation on production. He corrected the records somewhat for age differences by grouping the records of the cows by six months age intervals (2-0 to 2-6, 2-6 to 3-0, 7

etc.). A significant correlation was found between milk pro­

duction and the days a cow carried calf during her 3&5 day lac­

tation. He estimated a difference of 400 to 600 pounds of milk between cows carrying calf nine months and cows standing open during the entire lactation. He also concluded from this study

that gestation effects were least on young and old cows and greatest on five-year-old cows.

Gaines and Davidson (2*0 reported no differences in records of cows which carried calf less than five months compared with those not carrying calf during their 3&5 day lactation. These investigators also used Advanced Registry Guernsey records in this study.

Eckles and Anthony (15) conducted a study of the effect of gestation on production. Lactation records from 19 cows, which had a calving interval of one year or less for one lactation and then did not conceive for six months or more during another lactation, were compared. They reported that in the lactation where conception did not take place for at least six months, the

365 day records of the animals averaged 1,1**2 pounds more of milk and 56 pounds more of butterfat. The decline in production seemed to increase more rapidly in the pregnant cows after the fifth or sixth month of gestation. Hevens (47) also reported that the production decreasing effect of gestation seemed to begin after the first five months of pregnancy. He concluded that a ten-month lactation was depressed no more than 200 to 8

500 pounds of fat-corrected milk, due to the effects of ges­ tation.

Erb et al. (17) studied the effect of gestation on pro­ duction by using 82 intra-herd records, which were made under conditions where the cows were fed and managed for near maximum production. Daily production records from 40 Holsteins, eight

Jerseys and five Guernseys were included in the study. These authors reported that production of the Jerseys and Guernseys dropped rapidly for the first ten days after conception. They also observed the first noticeable effect of gestation on pro­ duction about 180 days after conception, regardless of the number of days after calving. The records were grouped by production levels and a variation in the intensity of decline in production was noticed; however, these differences in rate of decline were insignificant. They also observed less effect of gestation on production in two- and three-year-old cows than in older cows.

No difference in effect of gestation was observed when records from cows milked two- and three-times per day were considered.

The rate of decline in milk production 180 days after conception was twice as fast in cows conceiving in April and May as compared with those conceiving in June.

In a later study which involved 2,491 Dairy Herd Improve­ ment Association records, Erb (16) studied the effect of ges­ tation on production records that were adjusted for dry period and length of lactation. He observed an average difference in 9 production of 1,111 pounds of four percent milk between cows carrying calf 230 to 239 days compared with thoBe not carrying calf during the 305 day lactation. He concluded that a 305 day record was reduced about three quarts of four percent milk

(approximately 6.^5 pounds) for each day a cow was in calf over

100 days during the lactation.

Thompson et al. (58)* while studying the effects of several non-genetic factors on production, did not find a significant difference in production due to gestation.

Espe and Smith (18) estimated that cows in the tenth month of lactation, which have been pregnant for eight months, will give possibly 20 percent less milk than open cows.

Other Factors Affecting Production

As early as 1913i Carrol (7) studied the effect of varying length of dry period on production. He compared production records made after a one-month dry period, a two-month dry period, and a three-month dry period. He observed that a two-month dry period appeared more beneficial than either one-month or three- months. Numerous other investigators (1,2,3,11,16,29,3*0 agree that a dry period of something over 30 days but under 90 days is optimum. Goodwin and Erb (27) concluded that cows with a 0-9 day dry period averaged l,*t-59 pounds less of milk and 62 pounds less of butterfat in the following lactation than did cows that had a dry period of 50-59 days. 10

Tyler and Hyatt (60) analyzed the standardized mature

equivalent records of 2,203 cows to determine if length of calv­

ing interval had any effect on production. They reported sig­

nificantly lower production for those animals having a ten- or

eleven-month calving interval, when compared with those having a

calving interval of 12 months or more. They did not observe any

significant difference between those cows having a 12 or 13

months' calving interval and those having a 1^ or 15 months'

calving interval. Erb (l6) observed a considerable 305 day pro­

duction loss in cows having a calving interval of less than 360

days, but very little difference between cows having a calving

interval of 360 days or more. These investigators agree very

closely with the findings of other researchers (7 ,11,25) who have studied the effect of calving interval on production.

Carrol (7), in 1913, reported that cows freshening in the

fall produced more milk per lactation than did cows freshening in the spring. A few years later McDowell (39) also observed

that cows freshening in the fall had a higher average production

than those freshening at any other time of the year. Cows

freshening in the winter had the second highest production,

those freshening in the spring ranked third, and those which calved in the summer had the poorest production. Other investi­ gators (2,6,11,30,^8,53,58,59) have reported finding seasonal differences in production as great as 1,000 pounds of fat- 11 corrected milk, and generally agree that the fall or early winter months are the best times to freshen cows for optimum production.

Some investigators (63,6*0, however, report only minor differences due to season of freshening.

The influence of age at freshening on production has been demonstrated by numerous workers (2,9,11,15»22,31,32,33i58)•

Kendrick (31>32,33) calculated correction factors which are now commonly accepted and are popularly known as the standardized

2X, 305 day, mature equivalent factors. It was shown that two- year-old dairy cows generally produce a smaller amount of milk and butterfat than older cows and gradually increase in pro­ duction until they reach their maximum performance at six or seven years of age. They then slowly decline in level of pro­ duction as age increases.

It is generally agreed by those who have investigated the influence of times-milked per day on production that the more frequently a cow is milked per day (to as many as four-times per day), the more milk she produces (10,31,32,33,35,3 6 ,37). There is some disagreement, however, on the magnitude of the difference in production between cows milked two-times daily compared with those milked three- or four-times daily. Some workers (10) believe that .8 is the best factor to use to convert a three- time record to a two-time record, while others are of the opinion that .833 (32) is a better factor. Still others (36) feel that because of the greater persistency of two-year-old cows, their 12 three-time records should be multiplied by .8 while the three­ time records of older cows should be multiplied by .833 to convert them to a two-time basis* Some workers (8) also report an increased butterfat percentage when cows were milked three- times daily as compared to those milked twice daily, while others

(10) report a smaller increase in butterfat production than in milk production.

Production Record Evaluation

As early as 1920, McCandlish and Winters (38) computed factors that were used to standardize the production records of dairy cows. These investigators conducted a study comparing the production of the daughters of a bull with their dams. In order to make a more accurate comparison, they introduced age-al- lowance factors for records of the younger cows, and factored their records to a mature or five-year-old basis.

Ragsdale et al. (50), in 1924, analyzed 46,000 yearly records and 104,000 seven day records in a study designed to correct for age differences. They classified these records by yearly intervals based on age at freshening. The classified groups of records were averaged and plotted, and mature equiva­ lent factors were calculated from this plotted line. Other investigators (9,19) performed similar studies and also computed correction factors for age differences. Others (6,23,52,53,54, 13

55) computed factors to correct for differences in length of dry period, season of freshening, and days carried calf.

In 1935* when the proved sire program was inaugurated, a set of all-breed age-conversion factors were calculated by the

United States Department of Agriculture (31)• These factors were based on a study of the Dairy Herd Improvement Association pro­ duction records available at that time. By the use of these factors, an attempt was made to standardize for differences in age, length of lactation period, times milked per day and influ­ ence of gestation. These factors were revised in 19^1 (32), and individual factors were computed for each of the different breeds

(Ayrshire, Brown Swiss, Guernsey, Holstein, Jersey, and Short­ horn) . It was found that the age-conversion factors obtained for the Ayrshire, Jersey, and Guernsey breeds were not significantly different from each other, so they were combined. There were relatively few Shorthorn cows reported, so Brown Swiss data were used to develop factors for Brown Swiss and Shorthorn cows.

In 1955 (33)i the factors for standardized 2X, 305 day, mature equivalent production records were revised again. The factors published at that time were calculated from more than

500,000 records from dairy cows representing six breeds.

There has been some criticism of the standardized factors developed by the United States Department of Agriculture (36), but most dairymen and researchers have accepted these factors as 14

a valuable tool in the evaluation of dairy production records

which are used in the sire proving program and in research in

the field of dairy science.

Factors have also been computed (21,37,61) which are valu­

able in calculating partial records to 305 day completed records.

Records adjusted by the use of these factors have been shown to

have a high correlation with the actual completed records.

Physiological Aspects of the Effect of Gestation on Lactation

Within the last four decades, considerable research has been

conducted in an effort to determine the role of the various hor­

monal and other physiological factors that control lactation.

Some of this research has been performed with dairy cows and some with laboratory animals. Most researchers in the field of milk

secretion are of the opinion that production in dairy cattle is adversely affected, to some degree at least, by gestation. There is, however, considerable disagreement among these investigators as to the cause of this inhibition, and several theories have been proposed in an effort to explain this decreased production due to gestation.

One of the early theories was that decreased production due to gestation was caused by competition for nutrients by the grow­ ing fetus (14,24,28,47). Gowen (28) computed the nutrients required to produce a bovine fetus on an energy basis and con­ cluded that the requirement was 125-200 therms. This would be 15

equivalent to 400-600 pounds of milk. Brody et al. (4,5)

observed that the body weight of the gestating cow increased more

rapidly approximately the same time that the rate of decline in milk production increased. These researchers concluded that the

demand for nutrients required for the growth of the gestating

cow and those required to nourish the fetus, reduced by an equiva­

lent amount the supply available for the mammary gland, and

thereby reduced the production of the gestating cow.

Another of the earlier theories (15) on the effect of ges­

tation on production is that halfway through pregnancy, the

corpus luteum secretion stimulates some of the secretory cells of the mammary gland to grow rather than to secrete. These authors were of the opinion that as pregnancy advances, there is more growth and less secretion by these secretory cells and as a result milk yield decreases. At parturition, or shortly before, the corpus luteum degenerates and the secretory cells gradually become functional again. The experimental evidence leading to the development of this theory was obtained from experiments performed on goats.

The possibility that a hormone which inhibited milk pro­ duction was present during gestation, was advocated by Gaines and Davidson (24). Since then, there have been numerous experi­ ments in which the workers have tried to determine whether there were inhibitory effects of the various hormones present during pregnancy. 16

Folley (20) found that large doses of estrogenic hormones administered to dairy cows (as much as 485 milligrams of oestrone and 6? milligrams of dihydro-follicular-benzoate injected in five

doses over a period of two- and one-half days) had a temporary

inhibitory effect on production. However, when administration

of these estrogenic substances ceased, milk production returned

to normal. He also observed an increase in butterfat percentage and in solids-not-fat following the administration of these

estrogenic substances to dairy cows.

Spielman et al. (57) injected ten to 100 milligrams of

diethylstilbestrol at irregular intervals to four lactating

cows. These workers did not observe any effect on milk yield, but did observe an increased butterfat and lactose percentage.

These increased percentages returned to normal within five days after the last injection. Reece and Murphy (51) injected four lactating cows with diethylstilbestrol proprionate and observed

a decline in production in all four animals for a period of ten

days following injection. Meites and Turner (43) reported decreased lactation in rats due to injections of diethylstilbest­ rol. Donker and Peterson (12) found that ten milligrams of diethylstilbestrol given every second day to dairy cows increas­ ed production. When the same dosage was given every day, pro­ duction was either greatly inhibited or stopped entirely. Other workers (44,46) found that small doses of estrogen stimulated lactation in goats, but that large doses inhibited lactation. 1?

Nelson (^5) found that large amounts of oestrin were inhibitory to milk production in guinea pigs, while small amounts had little or no effect. He believed that oestrin may have inhibited the production of the lactogenic hormone or may have acted directly on the mammary gland.

Meites et al. (^2) has indicated that estrogen and pro­ gesterone may act together to inhibit the action of prolactin on the mammary gland. In his work with rabbits, he found that when either estrogen or progesterone was administered with prolactin, milk production remained high, but when both of these ovarian hormones were given with prolactin, milk production was decreased.

In later studies, Meites and Sgouris (40,4l) found that when rabbits were given amounts of estrogen and progesterone which were optimal for udder development, along with large doses of prolactin, a fair degree of lactation was obtained. When lesser amounts of the ovarian hormones were given, moderate amounts of prolactin were effective in initiating lactation. They con­ cluded that the level of estrogen and progesterone which is optimal for mammary growth does not completely inhibit lactation if a sufficient amount of prolactin is present. They were of the opinion that as pregnancy continues, the level of prolactin remains high as a result of continued milking stimulus, but as the level of progesterone and estrogen increases during later pregnancy, the action of prolactin in maintaining lactation is impaired and the level of milk production decreases. Walker and Mathews (62) observed that simultaneous in­ jections of estrogen and progesterone did not prevent the initi­ ation of lactation in rats, but that it did inhibit established lactation in this species.

One could conclude, from the literature reviewed, that the competition for nutrients is partially responsible for decreased production due to gestation in dairy cattle, but that the fluctuation in the levels of the various hormones present in the dairy cow during lactation and gestation is also partially responsible for this effect. MATERIALS AND METHODS

These data were taken from the Ohio North Central Dairy

Cattle Breeding Project.'*' This is a long-range project with the over-all objective of improving dairy cattle through breeding.

An objective of this nature necessitates a long-range program; therefore, many important additional projects have developed.

This analysis of the effect of gestation on production is one of these additional projects.

The cattle used in this project are owned and managed by the Ohio Department of Mental Hygiene and Correction. They are purebred Holstein-Friesians but registrations have not been kept up to date on all cattle. These cattle were in two herds located in different sections of the state. One herd is located at a mental institution and the other at a correctional insti­ tution. The management conditions in these herds are standard­ ized to the extent that both herds are under the supervision of the state's chief agriculturist. Management conditions do vary, however, because there are differences between the individual herdsmen. Also, management conditions vary from one herd to the other because of the differences in type and kind of feed availa-

------VA cooperative dairy cattle breeding project with the United States Department of Agriculture, the Ohio Agricultural Experiment Station and the Ohio Department of Mental Hygiene and Correction.

19 20 ble. Herd I (London Prison Farm) has somewhat better management conditions than herd II (Toledo State Hospital), but both herds are under relatively good management conditions.

Both of these herds are enrolled in a combination Herd Im­ provement Registry and Dairy Herd Improvement Association test­ ing program. All production records used in this study were obtained from these two sources, and were standardized to a 2X,

305 day, mature equivalent basis. All cows were milked three- times a day except those animaLs in herd II which freshened after January 1, 1956. These animals were milked twice a day.

The records of all cows milked three-times a day were adjusted to two-times by multiplying by .8. The Holstein Conversion

Factors shown in Table I (32) were used to standardize the records for age differences. The record of any cow going dry before 305 days was assumed to be a complete record. Any record that was started by or interrupted by an abortion (any calving of more than 151 days or less than 250 days gestation) was not used. Any record, other than first lactation records, that was preceeded by less than a ^fO day dry period or more than a 90 day dry period was not used. Any first lactation record from an animal that freshened before two years of age or over three years of age was not included in this study. This age restriction eliminated less than five percent of the records.

If other environmental influences were known to severely influence (if a decline in production of at least 50 percent 21

TABLE 1

AGE-CONVERSION FACTORS

Age Factor Age Factor Age Factor

2-0 1.377 5-0 1.017 8-0 1.018 2-1 1.360 5-1 1.015 8-1 1.021 2-2 1.343 5-2 1.013 8-2 1.024 2-3 1.326 5-3 1.011 8-3 1.027 2-4 1.309 5-4 1.009 8-4 1.030 2-5 1.292 5-5 1.007 8-5 1.033 2-6 1.275 5-6 1.006 8-6 1.036 2-7 1.263 5-7 1.005 8-7 1.039 2-8 1.251 5-8 1.004 8-8 1.042 2-9 1.239 5-9 1.003 8-9 1.045 2-10 1.227 5-10 1.002 8-10 1.048 2-11 1.215 5-11 1.001 8-11 1.051

3-0 1.203 6-0 1.000 9-0 1.054 3-1 1.191 6-1 1.000 9-1 1.057 3-2 1.179 6-2 1.000 9-2 1.060 3-3 1.167 6-3 1.000 9-3 1.063 3-4 1.155 6-4 1.000 9-4 1.066 3-5 1.143 6-5 1.000 9-5 1.069 3-6 1.131 6-6 1.000 9-6 1.072 3-7 1.122 6-7 1.001 9-7 1.075 3-8 1.113 6-8 1.002 9-8 1.078 3-9 1.104 6-9 1.003 9-9 1.081 3-10 1.095 6-10 1.004 9-10 1.084 3-11 1.086 6-11 1.005 9 - U 1.087

4-0 1.077 7-0 1.006 10-0 1.090 4-1 1.070 7-1 1.007 10-1 1.094 4-2 1.063 7-2 1.008 10-2 1.098 4-3 1.056 7-3 1.009 10-3 1.102 4-4 1.049 7-4 1.010 10-4 1.106 4-5 1.042 7-5 1.011 10-5 1.110 4-6 1.035 7-6 1.012 10-6 1.114 4-7 1.032 7-7 1.013 10-7 1.118 4-8 1.029 7-8 1.014 10-8 1.122 4-9 1.026 7-9 1.015 10-9 1.126 4-10 1.023 7-10 1.016 10-10 1.130 4-11 1.020 7-11 1.017 10-11 1.134 22 occurred at the time of obvious accident, injury, sickness etc. and the decline persisted) a production record, this record was eliminated from this study.

A preliminary survey showed approximately an equal distri­ bution of calvings by months and seasons of the year. Since this equal distribution existed, no effort was made to adjust for season of freshening.

This study involves 1,508 standardized 2X, 305 day, mature equivalent records. Of these, 680 were records from two-year- old cows, **80 were from three- and four-year-olds, and 3^8 were records made by cows five-years-old or older. The records were made in two herds over a period of ten years. The number of days open (that is, the number of days during the 305 day lactation that the cow was not pregnant) was calculated from the day of freshening to the day of conception. Since the term "days open" is easily and accurately computed, it will be used in all further discussions. It is understood that "days open" is inversely related to the period of gestation during lactation. If con­ ception did not occur within 305 days of the date of freshening, the animal was credited with 305 days open regardless of the eventual date of conception.

A multiple regression analysis, as explained by Snedecor

(5 6 ), was considered a logical approach to this study. The regressions of production on days open squared and days open cubed, as well as production on days open, were calculated. 23

This was done to determine whether the relationship might be represented better by an exponential function than a linear one.

The data were punched on IBM cards to facilitate the analysis.

There were 15 independent variables involved in this analysis:

1 . the year 19^7

2 . the year 19^8

3. the year 19^9

k . the year 1950

5- the year 1951

6 . the year 1952

7. the year 1953

8 . the year 195^

9. the year 1955

1 0 . the year 1956

1 1 . herd

1 2 . age

13- days open

l*f. days open. squared

15. days open. cubed

The two dependent variables were milk and butterfat pro­ duction. z b

The multiple regression formula for case 1 (the regression

of milk production on days open) follows:

Y1 = blXla + b2X2a + b3X3a------b15X15a + bl6 where:

b.X.. thru b_X_. = variance due to years 19^7 thru 1956 1 la 9 9a bn_.Xn_ = variance due to herd 10 10a b^i^lla = variance due to age

b^^X^2a = variance due to days open

b ^ X ^ a = variance due to days open squared

b ^ X ^ a = variance due to days open cubed

b ^ X ^ ^ = milk production

bl6 =! cons^an'*' Case 2, where butterfat production was the dependent variable, was calculated using the same formula as that used when milk production was the dependent variable.

Multiple regression coefficients were obtained for milk production and for butterfat production on days open, days open

squared and days open cubed. These coefficients were calculated with the influences of year, herd, and age removed. These co­ efficients measured the effect of gestation on production devoid of many environmental influences which might bias the results.

The data were also sorted into three groups according to age at freshening. The groups were (1) two-year-olds, (2) three- and four-year-olds, and (3) five-year-olds and over. A 25 multiple regression was calculated on each of these groups using the same basic formula described earlier.

The "t” test was used to test the significance of the multiple regression coefficients and an F-ratio was calculated to test the significance of the multiple correlation coefficients.

Correction factors were calculated from the regressions by dividing the daily increase due to days open by mean lactation production, and adding this amount for each day open less than

85, and subtracting this amount for each day open over 8 5 . This period of 85 days was used as the standard because those cows bred back about 85 days after freshening have a calving interval of approximately one year. This annual calving interval is considered optimum by most dairymen. RESULTS AND DISCUSSION

In a study of this nature it is difficult to control all environmental factors that might influence the data or the in­ terpretation of the results. In this study, year, herd, and age differences were corrected by the use of the multiple regression analysis. Length of previous dry period was corrected to a large extent, by elimination of those records that were not preceeded by a 40-90 day dry period. The production records were not corrected for differences due to season or month of freshen­ ing since these influences were assumed to be very minor because of equal distribution. The records were factored to a 2X, 305 day, mature equivalent basis. This procedure adjusted for differences due to age at freshening, times milked daily, and length of lactation. Elimination of records in which an a- bortion, severe accident or injury, disease, etc. occured should also help eliminate other environmental influences that might bias the data.

It is possible that other unobserved environmental influ­ ences could have affected the data. Some of these might have been changes in types, amount and quality of feed available, changes in milking procedure and management personnel, changes in genetic composition of the herds, and unrecorded health conditions. In this study, however, an effort was made to

26 27 standardize the data so that the results would be an accurate estimate of the effect of days open on milk and butterfat pro­ duction in Holstein dairy cows.

Table 2 gives a summary of the results of the multiple regression analysis of milk and butterfat production with days open of all records included in the study (1,508 observations).

The multiple regression coefficients measured the effect of days open on milk and butterfat production, after the records had been corrected for effect of year, herd and age at freshening.

It can be observed from Table 2 that the regressions for the squared and cubed values were smaller than the regressions for the unit values for production on days open. The standard deviations for the exponential functions were also much higher than the standard deviations for the linear values. For this reason, the remainder of the analysis and evaluations was con­ cerned only with the linear regression of milk and butterfat pro­ duction on days open.

A highly significant relationship (.01 level of probability) was observed both in the multiple correlations and in the multiple regressions between milk and butterfat production and days open. The multiple regression coefficient of 8.3265 for milk and .2633 for butterfat indicated that for each additional day open, the average cow in this study produced 8.3265 pounds more of milk and .2633 pounds more of butterfat during that lactation. At the level of production of the cows in this study TABLE 2

SUMMARY OF THE MULTIPLE REGRESSION ANALYSIS OF MILK AND BUTTERFAT PRODUCTION WITH DAYS OPEN IN HOLSTEIN COWS (1,508 OBSERVATIONS)

X Sx B^ Sx of B]_ t r R F

Days Open 131.16 76.3 Milk 12702.8 208U.7 Butterfat UU3»6 62.59 Days Open with Milk 8.3265 .8253 10.0892b .2363 .3609 18.6562b Days Open with Butterfat .2633 .0299 8.7983b .1967 .3832 2i.lUi.Ol4b (Days Open) 2 with Milk 2.768U 1.0693 2.5889b .2123 .3662 17.8023b (Days Open) 2 with Butterfat .0905 .0388 2.33U3a .1767 .3872 20.2692b (Days Qpen)3 with Milk 1 .08US 10.05U5 1.0786 .1920 .3662 16.5206b (Days Open) 3 with Butterfat .09IIU .36U7 2.5892b .I60U .3873 18.811M b

a - significant at .05. Sx of Bn - standard deviation of multiple regression. b - significant at .01. t - t-value for multiple regression. X - mean. r - simple correlation coefficient. Sx - standard deviation. R - multiple correlation coefficient. B]l - multiple regression coefficient.. F - F-ratio for multiple correlation.

ro 00 29

(average 12,703 pounds of milk and 443.6 pounds of butterfat), the difference in production due to gestation between a cow that conceived 85 days after freshening and one that did not conceive during the 305 day lactation was 1,832 pounds of milk and 58 pounds of butterfat.

The results of the multiple regression analysis of milk and butterfat production with days open on two-year-old, first lac­ tation records are given in Table 3« The multiple regression and correlation coefficients were smaller for this group than they were when all cows were considered. These values were 5*74l4 pounds of milk and .1595 pounds of butterfat per day open.

However, they did indicate a highly significant (.01 level of probability) relationship between days open and milk and butter­ fat production in two-year-old Holstein cows. The average pro­ duction, 13,202 pounds of milk and 461.9 pounds of butterfat, was higher for this group than the group which included all cows.

The average days open was about the same for both groups (131.16 days for all cows and 134.14 for the two-year-olds). The average difference in production, attributable to gestation, of cows which conceived 85 days after calving and those which did not conceive during the 305 day lactation was 1,263 pounds of wriIk and 35 pounds of butterfat per lactation.

In Table 4, a summary is given of the results of the multi­ ple regression analysis of milk and butterfat production.with days open of three- and four-year-old Holstein cows. Regressions TABLE 3

SUMMARY OF THE MULTIPLE REGRESSION ANALYSIS OF MILK AND BUTTERFAT PRODUCTION WITH DAYS OPEN IN TWO-YEAR-OID HOLSTEIN CCMS (680 OBSERVATIONS)

X Sx Bi Sx of B^ t r RF

Days Open 13U«lU 68.1U

Milk 13201.9 1967.2

Butterfat I46I.9 72.7

Days Open with Milk 5.7U1U I.D4OI 5.0358b .1687 .2605 U.2il98b

Days Open with Butterfat .1595 .0U12 3 .870i;b .1056 .3313 7.U876b

b - significant at .01. Sx of B^ - standard deviation of multiple regression. X - mean. t - t-value for multiple regression. Sx - standard deviation. r - simple correlation coefficient. B^ - multiple regression coefficient. R - multiple correlation coefficient. F - F-ratio for multiple correlation. TABLE 1+

SUMMARY OF THE MULTIPLE REGRESSION ANALYSIS OF MILK AND BUTTERFAT PRODUCTION WITH DAYS OPEN IN THREE- AND FOURr-YEAR-OID HOLSTEIN CONS (U80 OBSERVATIONS)

X Sx B^ Sx of B^ t r R F

Days Open 121+.9 55.0

Milk 12072.6 2071.0

Butterfat 1+25.0 78.1+

Days Open with Milk 8.571+5 1.6081 5 *3320b .2217 .3910 9.i£63b

Days Open with Butterfat .30U0 .0399 5.0768b .2082 .1+237 ll.l+280b

b - significant at .01. Sx of Bj - standard deviation of multiple regression. X - mean. t - t-value for multiple regression. Sx - standard deviation. r - simple correlation coefficient. B]_ - multiple regression coefficient. R - multiple correlation coefficient. F - F-ratio for multiple correlation. 32 of 8.5745 pounds of milk and .304-0 pounds of butterfat daily were observed in this group of cows. The multiple regression and correlation coefficients again indicated a highly significant

(.01 level of probability) relationship between days open and production. The mean days open was 124.9 days which was lower than that of the previous groups. The mean production of 12,073 pounds of milk and 4-25.6 pounds of butterfat was also lower than that of the previous groups. In this study the mean difference in production due to days open between a cow that conceived 85 days after calving and one which did not conceive during the lac­ tation was 1,887 pounds of milk and 67 pounds of butterfat per

305 day lactation. The magnitude of the effect was very similar to that obtained for all animals.

A summary of the results of the multiple regression analysis on the five-year-old and over group is given in Table 5* The multiple regression coefficients of 12.2057 pounds per day for days open and milk and .4189 pounds per day for days open and butterfat, as well as the multiple correlation coefficients, were highly significant (.01 level of probability). The means for milk and butterfat production as well as that for days open, were nearly the same as those for the overall group. The regression coefficients were the highest for this group, indi­ cating that gestation probably has more effect on older cows than on younger cows. In this group of cows, the difference in production due to days open between cows conceiving 85 days TABLE 5

SUMMARY OF THE MULTIPLE REGRESSION ANALYSIS OF MILK AND BUTTERFAT PRODUCTION WITH DAYS OPEN IN FIVE-YEAR-OLD OR OVER HOISTEIN COWS (3U8 OBSERVATIONS)

X Sx Bi Sx of B-l t r R F

Days Open 133*9 60.6

Milk 12^96.9 2080.9

Butterfat k 3 3 •7 72.3

Days Open with Milk 12.2057 1 .631a 5.0525b .370I4. .5028 12.707Ub

Days Open with Butterfat •U189 *0581 7 .2072b .3600 •I4.668 10.U638b

b - significant at .01. Sx of Bt - standard deviation of multiple regression, X - mean. t - t-value for multiple regression, Sx - standard deviation. r - simple correlation coefficient. B^ - multiple regression coefficient. R - multiple correlation coefficient. F - F-ratio for multiple correlation. after freshening and those not conceiving was 2,685 pounds of milk and 92 pounds of butterfat for each 305 day lactation.

Figures 1 and 2 are graphic presentations of the regressions of milk production on days open and butterfat production on days open for two-year-old cows, three- and four-year-old cows, five- year-old or over cows, and for all cows.

A summary of the regression coefficients of all studies and the calculated differences in production due to days open between cows which conceived 85 days after freshening and those which did not conceive during the 305 day lactation is given in Table

6. It can be observed from this table that the regression co­ efficients and the differences in production due to an additional

220 days open for the all-cows group and for the three- and four- year-old group is very similar. The regression coefficients and the difference in production for the two-year-old group are con­ siderably less than any of the other groups. This difference is probably due, in part, to the higher persistency of first lac­ tation cows. The regression coefficients and production differ­ ences in the five-year-old group were more than twice as high as the two-year-old group and somewhat higher than that of the three- and four-year-old group. Decreased persistency in older cows probably accounts for part of this difference.

It is also shown in Table 6 that the mature equivalent pro­ duction level was the highest in the two-year-old group, second highest in the five-year-old and over group, and lowest in the Pounds of Kilk 11000 12000 13000 15000 16000 O O O h l r- Figure1. Regressions of Kilk Production on Days Open. All Cows Two-Year-OldCows Five-Year-Old and Over Cows. Three-and Four-Year-OldCows 60 .... 120 as Open Days _L

...... 180 _L

2ii0 300 35 Pounds of Butterfat U00 hhO hQO 520 560 600 Figure 2# Regressions of Butterfat Productionon DaysOpen. All Cows Five-Year-Oldand . . Over Cows Three- and Four-Year-Old , CowsTwo-Year-Old Cows 60 ...... 120 as Open Days

......

...... 180 -L

21*0 * *- -* 300 36 TABLE 6

SUMMARY OF MULTIPLE REGRESSION COEFFICIENTS AND CALCULATED DIFFERENCES IN PRODUCTION DUE TO DAYS OPEN BETWEEN THOSE COWS CONCEIVING 85 DAYS AFTER FRESHENING AND THOSE NOT CONCEIVING DURING THE 305 DAY LACTATION

MILK BUTTERFAT Age Group N X Prod. % Pounds X Prod. Bp Pounds Difference Difference

1. Two-Year-Olds 680 13202 5.7U1U 1263 : 1*61.9 .1595 35.1

2. Three- and Four-Year-Olds U80 12073 8.575U 1886 U25-0 .30L0 66.9

3. Five-Year-Olds or Over 3U8 12597 12.2057 2685 1*33.7 .1089 92.2

1|. All Cows 1508 12703 8.3265 1832 1*1*3.6 .2633 57.9

N - number of cows. X - mean. Bp - multiple regression coefficient. 38 three- and four-year-old group. This fact indicates that possibly the age-conversion factors used in this study were slightly high for the two-year-old cows and somewhat low for the three- and four-year-old cows.

A difference in production from 1,263 to 2,685 pounds of milk and from 35 to 92 pounds of butterfat per 305 day lactation due to the effect of carrying calf 220 days or not carrying calf during the lactation could be important to many people. Those in charge of selecting bulls for use in artificial insemination could more accurately evaluate the performance of the animals involved. At present, much time and effort is expended by bull selection personnel in evaluating environmental conditions under which the daughters of a bull have made their production records.

At best, these evaluations are somewhat of an estimate of hov; much the daughters' records were influenced by varied environ­ mental conditions. It is the opinion of the author that it would be time well spent to correct these records for effect of days open on production. This would discourage breeders from the practice of delayed breeding which is sometimes used in an effort to obtain an impressive proof on a bull.

Farmers and breeders would also do well to consider the effects of days open on production when selecting young bulls or female replacement stock for their herds. Many cows are not rebred or fail to conceive until they are well along in their lactation, thus giving them an opportunity to make a more im­ 39

pressive record. Many times bull calves or female offspring are

sold from these cows because they have made this high record. If

these records had been adjusted to correct for effect of days

open, certainly the prospective buyer would have had a better

indication of the producing ability of these cows.

Production records of dairy cows are the criteria used to

evaluate many research projects in the field of dairy science.

Feeding programs are often tested on the difference in production

of small groups of cows receiving the different rations to be

tested. Results of these feeding trials could be biased con­

siderably, if there were a wide variation in days open between

the groups of cows and if production differences due to vari­ ations in days open were not adjusted in the analysis. The difference in production due to effect of days open could be as large or larger than the difference in production due to the effect of the different rations. Results of other dairy cattle research projects such as breeding experiments, housing projects, grazing trials, and many others could be misinterpreted if there were large variations in days open between the groups being compared.

Because of the magnitude of the effect of days open on miIV and butterfat production in dairy cattle, it was thought that correction factors, based on the results of this study should be calculated. It is realized that the number of animals (1,508) in this study is not exceedingly large and that only one breed kO of dairy cattle (Holstein-Friesian) is represented. However, be­

cause of the controlled conditions of the experiment and the analysis used, these correction factors should be relatively un­ influenced by environmental factors.

In Tables 7» 8, 9i and 10, the correction factors are pre­ sented that were calculated from the data on all-cows, two-year- olds, three- and four-year-olds, and five-year-olds and over, respectively. Correction factors are given for milk, butterfat, and fat-corrected milk.

The correction factors for each group were calculated by dividing the multiple regression coefficients (milk and butterfat) by the mean production (milk and butterfat). The percent-per- day increase due to days open was obtained by this calculation.

The days open, from 21 to 305» were divided into five-day inter­ vals (21-25, 26-30, etc.). The 81-85 day interval was designated as the standard (1.000) because cows which conceive 81-85 days after calving freshen again in approximately 12 months. This 12 month calving interval is considered optimum and is the goal of most dairymen. The correction factors were calculated by adding five-times the percent-per-day increase to each five-day inter­ val which was less than 81-85 days, and subtracting the same amount from each five-day interval more than 81-85 days.

Since there is only a small difference between the cor­ rection factors for milk and those for butterfat, one might question the practicability of two sets of factors. For this TABLE 7

FACTORS TO CORRECT FOR INFLUENCE OF GESTATION ON PRODUCTION OF HOLSTEIN COWS (ALL AGES)

Correction Factors Correction Factors Days Days Milk Fat F.C.M. Milk Fat F.C.M. Open Open

21-25 1.039 1.036 1.037 166-170 .944 .950 .947 26-30 1.036 1.033 1.034 171-175 .941 • 947 .944 31-35 1.033 1.030 1.031 176-180 .937 .944 .941 36-40 1.030 1.027 1.028 181-185 .934 .941 .938

41-45 1.026 1.024 1.025 186-190 .931 • 938 .935 46-50 1.023 1.021 1.022 191-195 .928 .935 .932 51-55 1.020 1.018 1.019 196-200 .924 • 932 .929 56-60 1.016 1.015 1.016 201-205 .921 .929 .925

61-65 1.013 1.012 1.012 206-210 .918 .926 .922 66-70 1.010 1.009 1.009 211-215 .914 .923 .919 71-75 1.007 1.006 1.006 216-220 .911 .920 .916 76-80 1.004 1.003 1.003 221-225 .908 .917 .913

81-85 1.000 1.000 1.000 226-230 .905 .914 .910 86-90 .997 .997 .997 231-235 .901 .911 .907 91-95 .993 .994 .994 236-240 .898 .908 .904 96-100 .990 .991 .991 241-245 .895 .905 .901

101-105 .987 .988 .988 246-250 .891 .902 .897 106-110 .984 .985 .984 251-255 .888 .899 .894 111-115 .980 .982 .981 256-260 .885 .896 .891 116-120 .977 • 979 • 978 261-265 .882 .893 .888

121-125 .97^ .976 .975 266-270 .878 .890 .885 126-130 .970 .973 .972 271-275 .875 .887 .882 131-135 .967 .970 .969 276-280 .872 .884 .879 136-140 .964 .967 .966 281-285 .868 .881 .876

141-145 .961 .964 .963 286-290 .865 .878 .873 146-150 .957 .961 .960 291-295 .862 .875 .869 151-155 • 95^ .958 .956 296-300 .859 .872 .866 156-160 .951 .955 .953 301-305 .855 .869 .863

161-165 • 947 • 952 • 950 42

TABLE 8

FACTORS TO CORRECT FOR INFLUENCE OF GESTATION ON PRODUCTION OF HOLSTEIN COWS (TWO-YEAR-OLDS)

Correction Factors Correction Factors Days Days Milk Fat F.C.M. Milk Fat F.C.M. Open Open

21-25 1.026 1.021 1.023 166-170 .963 .971 .967 26-50 1.024 1.019 1.021 171-175 .961 .969 .965 31-35 1.022 1.017 1.019 176-180 .959 .967 .964 36-40 1.020 1.016 1.017 181-185 .957 .965 .962

41-45 1.017 1.014 1.015 186-190 .954 .964 .960 46-50 1.015 1.012 1.013 191-195 .952 .962 • 958 51-55 1.013 1.010 1.012 196-200 • 950 .960 .956 56-60 1.011 1.009 1.010 201-205 .948 • 959 .954

61-65 1.009 1.007 1.008 206-210 .946 • 957 • 952 66-70 1.007 1.005 1.006 211-215 .943 .955 • 950 71-75 1.004 1.003 1.004 216-220 .941 .953 .948 76-80 1.002 1.002 1.002 221-225 • 939 • 952 .946

81-85 1.000 1.000 1.000 226-230 • 937 .950 .944 86-90 .998 .998 .998 231-235 .935 .948 .942 91-95 • 996 .997 .996 236-240 .933 .947 .940 96-100 .993 .995 .994 241-245 • 930 .945 .939

101-105 .991 • 993 .992 246-250 .928 .943 .937 106-110 .989 .991 • 990 251-255 .926 .941 .935 111-115 .987 .990 .988 256-260 .924 .940 • 933 116-120 .985 .988 • 987 261-265 .922 .938 .931

121-125 .983 .986 .985 266-270 .920 .936 • 929 126-130 .980 .984 .983 271-275 .917 • 934 .927 131-135 .978 .983 .981 276-280 • 915 • 933 .925 136-14-0 .976 .981 .979 281-285 • 913 • 931 .923

14-1-14-5 • 974 .979 • 977 286-290 .911 .929 .921 14-6-150 • 972 .978 .975 291-295 .909 .928 .919 151-155 • 970 • 976 .973 296-300 .906 .926 .917 156-160 .967 .974 .971 301-305 .904 .924 .916

161-165 .965 • 972 .969 TABLE 9

FACTORS TO CORRECT FOR INFLUENCE OF GESTATION ON PRODUCTION OF HOLSTEIN COWS (THREE- AND FOUR-YEAR-OLDS)

Correction Factors Correction Factors Days Days Milk Fat F.C.M. Milk Fat F.C.M. O-pen Open

21-25 1.043 1.043 1.043 166-170 .940 .939 • 939 26-30 1.039 1.039 1.039 171-175 • 936 • 936 .936 31-35 1.036 1.036 1.036 176-180 .933 .932 .932 36-40 1.032 1.032 1.032 181-185 • 929 .928 .929

41-45 1.028 1.028 1.028 186-190 .925 .925 .925 46-50 1.025 1.025 1.025 191-195 .922 .921 .922 51-55 1.021 1.021 1.021 196-200 .918 .918 .918 56-60 1.018 1.018 1.018 201-205 .915 .914 .914

61-65 1.014 1.014 1.014 206-210 .911 • 911 .911 66-70 1.011 1.011 1.011 211-215 .908 • 907 .907 71-75 1.007 1.007 1.007 216-220 .904 .903 • 904 76-80 1.004 1.004 1.004 221-225 .901 .900 .900

81-85 1.000 1.000 1.000 226-230 .897 .896 .897 86-90 .996 .996 .996 231-235 .893 .893 .893 91-95 .993 .993 • 993 236-240 .890 .889 .889 96-100 .989 .989 .989 241-245 .886 .886 .886

101-105 .986 .986 .986 246-250 .883 .882 .882 106-110 .982 .982 .982 251-255 .879 .878 .879 111-115 .979 • 979 .979 256-260 .876 .875 .875 116-120 .975 • 975 .975 261-265 .872 .871 .872

121-125 .972 .972 .972 266-270 .869 .868 .868 126-130 .968 .968 .968 271-275 .865 .864 .865 131-135 .964 .964 .964 276-280 .861 .861 .861 136-140 .961 .961 .961 281-285 .858 .857 .857

141-145 .957 .957 .957 286-290 .854 .853 .854 146-150 .954 .954 • 954 291-295 .851 .850 .850 151-155 .950 .950 .950 296-300 .84? .846 .847 156-160 .947 .946 .947 301-305 .844 .843 .843

161-165 .943 .943 .943 TABLE 10

FACTORS TO CORRECT FOR INFLUENCE OF GESTATION ON PRODUCTION OF HOLSTEIN COWS (FIVE-YEARS-OLD OR OVER)

Correction Factors Correction Factors Days Days Milk Fat F.C.M. Milk Fat F.C.M. Open Open

21-25 1.058 1.058 1.058 166-170 .918 .918 .918 26-30 1.053 1.053 1.053 171-175 .913 • 913 .913 31-35 1.048 1.048 1.048 176-180 .908 .908 .908 36-40 1.044 1.043 1.044 181-185 • 903 .903 .903

41-45 1.039 1.039 1.039 186-190 .898 .899 .898 46-50 1.034 1.034 1.034 191-195 .893 .894 .894 51-55 1.029 1.029 1.029 196-200 .889 .889 .889 56-60 1.024 1.024 1.024 201-205 .884 .884 .884

61-65 1.019 1.019 1.019 206-210 .879 .879 .879 66-70 1.015 1.014 1.015 211-215 .874 .874 .874 71-75 1.010 1.010 1.010 216-220 .869 .870 .869 76-80 1.005 1.005 1.005 221-225 .864 .865 .865

81-85 1.000 1.000 1.000 226-230 .860 .860 .860 86-90 • 995 • 995 .995 231-235 .855 .855 .855 91-95 • 990 • 990 • 990 236-240 .850 .850 .850 96-100 .985 .986 .985 241-245 .845 .845 .845

101-105 .981 .981 .981 246-250 .840 .841 .840 106-110 .976 • 976 • 976 251-255 .835 .836 .836 111-115 .971 .971 .971 256-260 .830 .831 .831 116-120 .966 .966 .966 261-265 .826 .826 .826

121-125 .961 .961 .961 266-270 .821 .821 .821 126-130 .956 • 957 .956 271-275 .816 .816 .816 131-135 .952 .952 .952 276-280 .811 .812 .811 136-140 .947 .947 .947 281-285 .806 .807 .807

141-145 .942 .942 .942 286-290 .801 .802 .802 146-150 • 937 .937 .937 291-295 .797 .797 • 797 151-155 • 932 • 932 .932 296-300 .792 .792 • 792 156-160 • 927 .928 .927 301-305 .787 .788 .787

161-165 .922 .923 .923 h5 reason, a set of factors was also calculated for fat-corrected milk. This was done by calculating a fat-corrected milk multiple regression coefficient from the milk and butterfat multiple regression coefficients for each group and dividing this by the mean fat-corrected milk for each group. The correction factors were then calculated from this percent-per-day increase in the same way as were the factors for milk and butterfat.

It is the opinion of the author that, due to the wide difference between the effect of days open on production at the different ages, the correction factors derived from the all ages study would not be accurate enough for general usage. They could be useful, however, where only a rough estimate is needed, or in cases where the age of the cow is in question.

The correction factors calculated for the individual age groups will be of considerable value in future analysis at the

Ohio North Central Regional Breeding Project. It is believed that these factors should also be helpful to other researchers and to dairymen, especially in evaluating records of Holstein dairy cows. It is believed, even though the records used in this study were all from Holstein cows from two herds, that the correction factors should be of considerable aid in evaluating production records from dairy cows other than Holsteins and in locations other than Ohio. The factors may not be as accurate for other breeds, however, it is believed that the physiological effect of days open on production should be similar for all dairy k6 breeds. It is hoped that future investigations with other breeds will determine if there are breed differences or differences due to variable climates. SUMMARY AND CONCLUSIONS

The number of days between calving and conception (days open) was obtained for a group of Holstein-Friesian cows which had 1,508 production records. These cows were located in two different herds owned by the Ohio Department of Mental Hygiene and Correction, and the production records were made over a period of ten years. A multiple regression analysis was used to correct for yearly, herd, and age differences. Production records from cows that did not have a *K)-90 day dry period preceding the lactation were eliminated from the study in an effort to standardize the data.

The multiple regression coefficients for milk production on days open and for butterfat production on days open for all cows with 1,508 production records were 8.3265 for milk and .2633 for butterfat. These values for two-year-old cows (680) were 5*7^1^ for milk and .1595 for butterfat. Regressions of the production on days open of three- and four-year-old cows (480) were 8.57^5 for milk and .30^0 for butterfat. For five-year-olds or over

(3^8 ), the regressions were 12.2057 for milk and .4l89 for butterfat. All of these values were significantly different from zero at the .01 level of probability. ^7 k8

Under the conditions of this study, it was found that as days open increased, milk and butterfat production also in­ creased. This production increase was the least for two-year-old cows, somewhat larger for three- and four-year-olds, and the largest for older cows. Because of the magnitude of the effect of days open on production, correction factors were calculated.

These factors are presented for milk, butterfat, and fat-correct­ ed milk for each of the different age groups as well as for all cows. LITERATURE CITED

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25. Gaines, W. L. and Palfrey, J. R. Length of calving interval and average milk yield. J. Dairy Sci., 14: 294-306. 1931.

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28. Gowen, J. W. Intrauterine development of the bovine fetus in relation to milk yield in Guernsey cattle. J. Dairy Sci., 7: 311-317. 1924.

29. Hammond, J. and Sanders, H. G. Some factors affecting milk yield. J. Agr. Sci., 13: 74-117* 1923.

30. Johnston, J. E., Lewis, C., Stone, E. J. and Branton, C. The influence of season of freshening on production records of Jersey and Holstein cows in Louisiana. J. Dairy Sci., 39: 933* 1956.

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34. Klein, J. W. and Woodward, T. E. Influence of length of dry period upon the quantity of milk produced in the subsequent lactation. J. Dairy Sci., 26: 705-713* 1943.

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37. Madden, D. E., McGilliard, L. D. and Ralston, N. P. Relations between monthly test-day milk production of Holstein-Friesian cows. J. Dairy Sci., 39s 932. 1956.

3 8 . McCandlish, A. C. and Winters, L. M. A study in bulls. J. Dairy Sci., 3s 529-539. 1920.

39* McDowell, J. C. Influence of season of freshening on production and income from dairy cows. United States Department of Agriculture Bulletin 1071. 1922.

40. Meites, J. and Sgouris, J. T. Can the ovarian hormones inhibit the mammary response to prolactin? Endocrin., 53: 17-23. 1953.

41. Meites, J. and Sgouris, J. T. Effect of altering the balance between prolactin and ovarian hormones on initi­ ation of lactation in rabbits. Endocrin., 55: 530-534. 1954.

42. Meites, J., Reineke, E. P. and Cairy, C. F. Induction of lactation in dairy cattle by diethylstilbesterol-pro- gesterone implants. J. Dairy Sci., 35: 506. 1952.

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45. Nelson, W. 0. Concerning the anterior pituitary-gonadal interrelations. Endocrin;, 19: 187-198. 1935*

46. Nelson, W. 0. Studies on the physiology of lactation. III. Reciprocal hypophyseal-ovarian relationship as a factor in the control of lactation. Endocrin., 18: 33-46. 1934.

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48. Plum, M. Causes of differences in butterfat production of cows in Iowa cow testing associations. J. Dairy Sci., 18: 811-825. 1935. 53

49. Ragsdale, A. C., Turner, C. W. and Brody, S. The effect of gestation upon lactation in the dairy cow. J. Dairy Sci., 7: 24-30. 1924.

50. Ragsdale, A. C., Turner, C. W. and Brody, S. The relation between age and fat production in dairy cows. J. Dairy Sci., ?: 189-196. 1924.

51. Reece, R. P. and Murphy, J. M. Influence of diethylstil- besterol diproprionate on the lactating mammary gland of the cow. J. Dairy Sci., 26: 748-749. 1943*

52. Sanders, H. G. The shape of the lactation curve. J. Agr. Sci., 13: 169-179. 1923.

53* Sanders, H. G. The variations in milk yields caused by season of the year, service, age and dry period, and their elimination. J. Agr. Sci., 17: 339-379* 1927*

54. Sanders, H. G. The variations in milk yields caused by season of the year, service, age and dry period, and their elimination. Part II. Service. J. Agr. Sci., 17: 502-523. 1927.

55* Sanders, H. G. The variations in milk yields caused by season of the year, service, age and dry period, and their elimination. J. Agr. Sci., 18: 209-251. 1928.

5 6 . Snedecor, G. W. Statistical Methods. The Iowa State College Press, Ames, Iowa. 1946.

57* Spielman, A., Ludwick, T. M. and Peterson, 7/. E. Effect of diethylstilbesterol on milk secretion. J. Dairy Sci., 24: 499. 1941.

5 8 . Thompson, N. R., Reaves, P. M., Kramer, C. Y. and Graf, G. C. Effects of seven non-genetic factors on butterfat production in a Guernsey herd. J. Animal Sci., 14: 1189. 1955.

59* Turner, C. W. Seasonal variations in milk and fat pro­ duction. J. Dairy Sci., 6 : 198-203. 1923*

60. Tyler, W. J. and Hyatt, G. Jr. Some of the effects of calving interval on milk and butterfat production of Ayrshire cattle. J. Dairy Sci., 33: 375* 1950.

61. Voelker, H. H. Use of extended incomplete lactation records. J. Dairy Sci., 40: 6 3 1 . 1957. 5^

62. Walker, S. M. and Mathews, J. I* Observations on the pre- partal and postpartal estrogen and progesterone treatment on lactation in the rat. Endocrin., ^4: 8-17* 19^9.

6 3 . Woodward, T. E. Some studies of lactation records. J. Dairy Sci., 28: 209-218. 19^5.

6*f. Wylie, C. E. The effect of season on the milk and fat pro­ duction of Jersey cows. J. Dairy Sci., 8 : 127-131. 1925. xicmaadv TABLE 11

ORIGINAL DATA FROM THE LONDON HERD

Cow No. Year Age Days Open Milk Butterfat

1284 1947 2 220 13090 471 1286 1947 2 305 14900 536 1295 1947 2 251 14320 530 1302 1947 2 255 15310 475 1503 1947 2 94 13490 513 1507 194? 2 196 12020 409 1315 1947 2 117 9450 303 1316 1947 2 119 11150 412 1318 1947 2 224 12970 428 1320 1947 2 299 13530 433 1321 1947 2 300 12180 390 1324 1947 2 263 13160 421 1325 1947 2 98 12430 435 1330 1947 2 305 14040 421 1331 1947 2 135 14850 475 1332 1947 2 243 15140 469 1334 1947 2 100 10320 361 1335 1947 2 202 10440 376 1336 1947 2 198 11060 365 1337 1947 2 98 12300 381 1374 1948 2 74 12800 415 1376 1948 2 158 11450 378 1377 1948 2 183 13420 403 1382 1948 2 180 11570 393 1383 1948 2 140 16230 536 1385 1948 2 161 13460 471 1389 1948 2 130 13970 510 1390 1948 2 255 13430 449 1392 1948 2 105 12860 4i8 1393 1948 2 90 15140 500 1398 1948 2 105 14070 459 1402 1948 2 78 10460 348 1404 1948 2 87 13520 473 1405 1948 2 107 13890 410 1407 1948 2 78 11150 375 1409 1948 2 137 14330 422 1412 1948 2 174 13490 407 1414 1948 2 165 11150 386 1417 1948 2 99 13390 407 1426 1948 2 131 11270 349 1435 1948 2 61 12150 4o4 56 57

TABLE 11 (Continued)

Cov No. Year Age Days Open Milk Butter:

1429 1948 2 98 13000 411 1419 1949 2 256 17840 457 1424 1949 2 124 12600 399 1425 1949 2 131 13430 408 1427 1949 2 140 13120 415 1436 1949 2 175 12740 41? 1437 1949 2 84 9140 294 1439 1949 2 101 11630 444 1440 1949 2 96 11390 331 1441 1949 2 102 11130 356 1443 1949 2 122 14250 432 1445 1949 2 95 14440 431 1446 1949 2 83 11180 375 1447 1949 2 107 12010 398 1448 1949 2 l4l 11200 353 1451 1949 2 194 11440 360 1452 1949 2 80 12570 383 1458 1949 2 122 13690 449 1459 1949 2 100 13230 429 1460 1949 2 122 13330 427 l46l 1949 2 92 13260 424 1462 1949 2 86 12280 409 1463 1949 2 102 13530 433 1464 1949 2 127 12070 389 1466 1949 2 233 12760 415 1467 1949 2 90 16900 603 1469 1949 2 85 13890 448 1470 1949 2 89 12690 398. 1471 1949 3 69 11090 375 1473 1949 2 114 12310 451 l4?4 1949 2 l4o 11830 498 1477 1949 2 172 12940 421 l48l 1949 2 127 13290 425 1484 1949 2 109 14650 476 1485 1949 2 129 13280 412 1487 1949 2 244 13490 473 1489 1949 2 l4l 12500 422 1490 1949 2 77 12150 380 1491 1949 2 115 13010 455 1492 1949 2 77 13290 447 1493 1949 2 103 12220 403 58

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

1494 1949 2 220 9650 305 1496 1949 2 85 12620 4l4 1^98 1949 2 132 15380 491 1499 1949 2 96 10640 352 1505 1949 "2 111 13560 422 1507 19^9 2 132 11270 374 1508 1949 2 97 14210 414 1509 1949 2 110 15230 489 1510 1949 2 91 12490 409 1497 1950 3 102 11380 370 1504 1950 2 103 12400 409 1506 1950 2 145 13350 454 1528 1950 2 149 10220 349 1531 1950 2 128 14350 454 1535 1950 2 154 10940 369 1538 1950 2 76 13780 444 1544 1950 2 86 14150 431 1549 1950 2 159 13590 485 1545 1950 2 112 13050 450 1547 1950 2 86 13000 430 1552 1950 2 99 9230 337 1554 1950 2 136 11910 407 1555 1950 2 104 13360 459 1558 1950 2 93 12190 385 1559 1950 2 113 13740 409 1560 1950 2 82 14010 509 1562 1950 2 161 11900 433 1563 1950 2 ill 11980 411 1564 1950 2 91 13050 478 1565 1950 2 98 11950 440 1566 1950 2 235 16170 591 1568 1950 2 129 13960 490 1570 1950 2 102 12030 444 1571 1950 2 120 13260 383 1573 1950 2 144 16150 578 1575 1950 2 150 loo4o 366 1582 1950 2 93 13940 454 1583 1950 2 83 15240 485 1588 1950 2 84 13660 488 1589 1950 2 156 16170 545 1574 1951 2 164 11490 413 59

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

1577 1951 2 111 12920 467 1585 1951 2 91 12220 437 1590 1951 2 85 12790 454 1595 1951 2 167 13250 434 1596 1951 2 90 17310 569 1597 1951 2 91 13170 446 1599 1951 2 95 11490 382 1600 1951 2 105 10620 406 1601 1951 2 103 11070 455 1602 1951 2 120 13210 506 1603 1951 2 80 11570 392 1606 1951 2 108 17980 567 1607 1951 2 116 14470 527 1609 1951 2 156 12300 415 1610 1951 2 161 16500 510 1613 1951 2 144 14800 523 1615 1951 2 305 15670 535 1625 1951 2 124 13600 480 1627 1951 2 97 12750 424 1632 1951 2 98 13080 447 1637 1951 2 79 12320 448 l64o 1951 2 103 13510 467 1642 1951 2 l4l 14520 503 1644 1951 2 107 11070 413 1645 1951 2 168 15190 489 1646 1951 2 242 9060 315 1649 1951 2 104 13580 462 1655 1951 2 179 14100 476 1660 1951 2 132 13360 515 1666 1951 2 87 11740 434 1668 1952 2 305 12540 463 1670 1952 2 305 14110 533 1674 1952 2 169 14660 559 1675 1952 2 122 12540 476 1678 1952 2 149 12350 558 1683 1952 2 116 11340 424 1684 1952 2 110 13070 482 1686 1952 2 184 13510 456 I687 1952 2 122 12910 466 1689 1952 2 211 8710 335 1690 1952 2 116 17820 612 60

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

1691 1952 2 104 15310 579 1692 1952 2 112 12120 426 1694 1952 2 92 14170 550 1695 1952 2 81 12100 425 1703 1952 2 84 11340 363 1707 1952 2 88 12590 . 436 1708 1952 2 160 13480 496 1711 1952 2 86 10220 363 1713 1952 2 106 13000 434 1716 1952 2 . 134 15080 577 1717 1952 2 151 12910 4ll 1719 1952 2 104 14760 535 1720 1952 2 125 14510 563 1723 1952 2 91 14280 478 1724 1952 2 82 13850 484 1725 1952 2 99 14680 494 1731 1952 2 133 14420 517 1735 1952 2 88 12220 477 17^3 1952 2 182 16420 603 1746 1952 2 145 15980 605 1747 1952 2 166 14330 524 1748 1952 2 108 11800 435 1738 1952 2 131 12620 431 1754 1953 2 83 12880 526 1753 1953 2 85 16120 615 1755 1953 2 246 14030 524 1757 1953 2 86 13110 471 1759 1953 2 77 11210 383 1762 1953 2 85 14560 554 1766 1953 2 96 10490 389 1767 1953 2 111 12600 478 1770 1953 2 85 12610 482 1772 1953 2 97 13000 500 1776 1953 2 92 13710 523 1777 1953 2 230 16730 603 1779 1953 2 115 13960 478 1780 1953 2 148 14440 563 1783 1953 2 125 15210 511 1784 1953 2 68 12590 479 1786 1953 2 78 12300 4ll 1789 1953 2 95 12790 524 61

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

1791 1953 2 112 15640 530 1794 1953 2 100 13300 526 1798 1953 2 305 14350 499 1799 1953 2 118 17770 608 1800 1953 2 151 15280 541 1801 1953 2 175 12810 421 1802 1953 2 83 9550 353 1803 1953 2 161 13880 521 l8o4 1953 2 132 13810 494 1808 1953 2 214 11500 438 1813 1953 2 92 13080 499 1817 1953 2 105 11980 394 1820 1953 2 77 13700 475 1823 1953 2 157 15070 511 1829 1953 2 106 11620 4o6 1830 1933 2 137 11890 422 1806 1954 2 97 11810 484 1828 1954 2 102 12640 450 1832 1954 2 103 15600 555 1834 1954 2 265 17170 592 1836 1954 2 166 13060 427 1845 1954 2 197 14070 480 1848 1954 2 84 12900 432 1853 1954 3 132 14400 508 1855 1954 2 81 15440 572 i860 1954 2 87 14110 450 1862 1954 2 100 13890 505 1864 1954 2 89 12450 474 1865 1954 2 96 14560 467 1868 1954 2 153 14010 519 1870 1934 2 75 11770 410 1871 1954 2 166 12780 486 1876 1954 2 98 13990 498 1881 1954 2 135 12560 479 1885 1954 2 108 14280 505 1886 1954 2 72 12800 509 1891 1954 2 93 12600 456 1897 1954 2 88 11680 438 1898 1954 2 168 12880 391 1899 1954 2 113 13460 436 1900 1954 2 109 13680 439 62

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

1901 1954 2 133 14870 461 1915 1954 2 89 l4l4o 504 1925 1954 2 76 13140 451 1933 1954 2 176 11450 371 1913 1955 2 156 13530 503 1924 1955 2 84 13740 498 1928 1955 2 186 13920 480 1930 1955 2 104 15210 573 1934 1955 2 92 12240 434 1937 1955 2 96 18670 651 1938 1955 2 111 16050 511 1939 1955 2 89 13680 481 1940 1955 2 78 13650 522 1942 1955 2 76 10000 385 1944 1955 2 122 13820 466 1946 1955 2 86 14350 499 1947 1955 2 85 15020 547 1948 1955 2 85 15120 501 1949 1955 2 107 14880 561 1950 1955 2 80 13470 511 1951 1955 2 87 12120 459 1953 1955 2 101 13330 4?8 1955 1955 2 90 16650 591 1957 1955 2 130 13260 509 1958 1955 2 87 12260 377 1959 1955 2 103 12100 443 I960 1955 2 273 13020 502 1962 1955 2 91 14470 554 1965 1955 2 79 13960 458 1969 1955 2 91 13680 503 1970 1955 2 97 9970 366 1971 1955 2 95 13880 545 1972 1955 2 305 14850 505 1973 1955 2 129 13620 471 1975 1955 2 91 13280 443 1976 1955 2 89 10540 435 1977 1955 2 96 12610 376 1989 1955 2 80 13490 4o6 1999 1955 2 79 13800 521 2001 1955 2 l4l 14600 547 2008 1955 2 106 13040 489 63

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

2020 1955 2 96 12010 423 1994 1956 2 219 14700 528 2000 1956 2 121 16780 535 2006 1956 2 187 14270 512 2015 1956 2 156 12460 455 2004 1956 2 86 12100 437 2018 1956 2 87 16570 563 2022 1956 2 89 17590 591 2026 1956 2 137 10500 425 2028 1956 2 115 12970 486 2032 1956 2 102 13260 474 2034 1956 2 158 14110 509 2035 1956 2 104 12580 472 2038 1956 2 89 13140 514 2039 1956 2 72 10690 376 2040 1956 2 93 11680 396 2041 1956 2 118 12680 463 2043 1956 2 100 10650 356 2046 1956 2 110 14690 525 2048 1956 2 113 11250 413 2049 1956 2 110 10270 426 2050 1956 2 237 12680 423 20 52 1956 2 248 13780 482 2056 1956 2 89 11480 4l4 2075 1956 2 99 13980 530 2076 1956 2 87 12930 479 2078 1956 2 88 12230 422 2082 1956 2 144 10330 401 2083 1956 2 96 10320 402 2092 1956 2 84 11870 438 2094 1956 2 98 10870 413 2094 1956 2 135 15730 544 2100 1956 2 105 11590 386 1287 1949 4 177 14260 485 1287 1950 5 305 12410 430 1287 1953 5 100 14800 517 1287 1954 5 99 13120 442 1288 1949 5 79 14950 530 1288 1950 5 78 13770 501 1288 1952 5 284 17260 635 1289 1949 4 81 12410 390 64

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

1289 1950 5 145 11120 364 1289 1951 5 206 14360 461 1289 1952 5 123 14760 493 1289 1953 5 144 17500 601 1290 1948 4 234 13170 446 1290 1950 5 130 11600 405 1293 1949 4 155 13000 440 1294 1952 5 111 13990 459 1295 1949 5 142 15820 529 1295 1951 5 126 14470 527 1295 1952 5 91 12640 415 1295 1953 5 100 14830 521 1295 1954 5 183 17850 574 1300 1949 4 230 12040 376 1300 1951 5 102 10790 381 1302 1950 5 282 16210 536 1307 1949 4 249 11380 398 1308 1949 5 176 17270 492 1308 1951 5 305 14630 504 1308 1954 5 247 18090 623 1309 1948 4 162 13780 449 1309 1950 5 131 13500 496 1309 1951 5 67 13370 455 1309 1953 5 167 11500 426 1314 1949 4 108 11320 361 1321 1952 5 256 15830 539 1328 1950 5 176 16530 543 1328 1951 5 189 12200 385 1330 1951 5 86 13230 429 1331 1949 4 167 16260 546 1331 1951 5 128 13400 452 1332 1950 4 123 13680 459 1332 1951 5 108 13170 460 1332 1952 5 102 12690 429 1342 1948 3 126 12300 376 1342 1950 4 149 12710 400 1342 1951 5 114 12970 4l4 1342 1953 5 94 11690 392 1342 1954 5 145 13130 446 1343 1952 5 98 12740 446 1343 1953 5 143 12670 439 65

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

13^-6 19^9 131 lOififO 32if 13^8 1950 if 9*f 120if0 if 36 13^8 1951 5 191 10120 36if 13*f8 1953 5 8if 12350 k z s 1352 1950 5 9**- 10050 3^1 1352 1951 5 101 10770 357 1355 1950 5 69 llif90 if2if 1365 1951 5 87 11560 355 137^ 1950 if 77 13620 i+66 137^ 1953 5 118 12lif0 391 1376 1950 if 108 10180 369 1376 1951 5 72 lOOifO 367 1377 19^9 if 73 llif 20 369 1377 1950 5 lifl 12250 385 1377 1952 5 122 12650 ^13 1377 1953 5 1^3 12810 ifll 1379 1951 5 98 13090 if52 1379 1952 5 160 lif920 if92 1379 1953 5 lif7 126ifO 399 1385 1950 if 9^ 11620 if31 1385 1951 5 87 10180 312 1385 1952 5 115 11000 38if 1385 195^ 5 86 13870 513 1390 1950 if 9if 12880 if5if 1390 1951 5 79 13^10 if 61 1390 1952 5 305 139^0 if8o 1393 1950 if 2 lif 11850 iflO 1393 1951 5 252 12770 if62 1393 1953 5 303 13190 if6if 1395 1950 if 169 12670 if02 1393 1951 5 138 12if30 if36 1395 1953 5 lif9 152if0 506 1398 19^9 3 lif2 lif020 if35 i k o k 1951 5 llif 12ifl0 if57 i k o k 1952 5 2if7 15550 539 i k o k 195*f 3 178 15610 521 i k o k 1955 5 179 15190 508 I k O ? 1950 if 112 11100 ifl3 l k 0 7 1952 5 92 12if50 ifif2 l k 0 7 1953 5 127 13850 k 7 & l k 0 9 1952 5 97 Iif5*f0 66

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

14-09 1953 5 118 11910 338 1409 1954 5 203 15240 502 1414 1951 4 125 10420 381 1414 1952 5 81 11550 4l4 14-14 1955 5 91 11610 415 1424 1951 5 126 12450 400 1424 1952 5 77 9510 292 1424 1953 5 145 12280 379 1424 1954 5 98 13810 430 1425 1950 4 156 15540 500 1425 1951 5 98 14410 471 1425 1953 5 145 12680 428 1425 1954 5 123 14810 511 1426 1950 3 79 13670 443 1426 1951 4 161 13590 444 1426 1952 5 134 13860 412 1426 1953 5 84 11510 356 1427 1950 3 121 12310 395 1427 1951 5 138 12520 413 1427 1952 5 79 9030 345 1429 1950 4 107 12640 437 1429 1951 5 305 14960 490 1429 1955 5 131 13420 480 1435 1949 3 127 12790 421 1435 1950 4 90 11830 418 1435 1951 5 83 11600 403 1435 1952 5 110 11670 389 1436 1952 5 91 11790 401 1439 1950 3 89 13700 432 1439 1951 4 182 12600 4l6 1439 1952 5 178 14640 473 1441 1950 3 125 12410 374 1441 1951 4 109 12810 356 1441 1952 5 255 12300 402 1445 1951 4 99 13810 451 1445 1954 5 96 l4o8o 430 1446 1950 3 190 12730 417 1446 1953 5 258 12250 417 1448 1951 4 105 11150 375 1448 1953 5 96 IO630 359 1448 1954 5 162 12230 386 67

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

14-51 1950 3 196 12990 399 14-51 1951 5 71 11750 388 14-51 1952 5 76 11970 387 14-51 1955 5 90 13480 437 1458 1951 4 148 13740 494 1458 1952 5 119 14120 488 1458 1955 5 115 14060 475 1458 1954 5 242 16230 565 1459 1952 5 96 13340 442 1459 1955 5 155 14350 463 1459 1954 5 179 14830 502 1461 1955 5 154 15780 556 1461 1956 5 121 15230 514 1462 1951 5 107 12480 443 1462 1954 5 305 14830 519 1463 1950 5 96 11830 385 1463 1951 4 112 11890 386 1463 1952 5 87 12680 422 1463 1953 5 164 14780 468 1463 1954 5 80 15060 495 1464 1950 4 174 12460 400 1466 1950 5 67 10470 382 1466 1951 4 126 12000 445 1466 1952 5 86 12070 433 1466 1953 5 139 13910 488 1466 1954 5 89 13060 460 146? 1955 5 139 10290 341 1467 1954 5 128 13830 454 1467 1955 5 107 13760 449 1467 1956 5 117 13110 415 1470 1951 4 93 12270 381 1470 1952 5 93 12240 357 1475 1951 4 90 10960 368 1475 1952 5 163 12660 432 1474 1951 4 138 10080 370 1474 1952 5 88 11650 4l4 1474 1954 5 93 12770 445 1477 1950 5 100 11840 391 1477 1951 4 118 12480 416 1477 1952 5 89 11530 374 1477 1953 5 179 14240 459 68

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

1477 1955 5 173 13990 492 1478 1932 5 81 10240 321 1478 1953 5 142 11810 386 1478 1954 5 187 11550 395 l48l 1951 4 155 13370 418 l48l 1952 5 114 13510 413 l48l 1953 5 159 12930 417 1485 1950 3 138 14490 480 1485 1951 4 100 10770 379 1485 1952 5 121 15490 466 1485 1953 5 300 14440 495 1485 1956 5 95 13630 436 1487 1950 3 74 14340 531 1487 1952 5 172 12020 417 1489 1951 4 153 11870 420 1489 1952 5 138 14400 484 1490 1955 5 273 14000 415 1491 1952 5 48 12210 477 1491 1953 5 233 13190 493 1491 1956 5 166 14880 530 1492 1951 4 100 12340 425 1492 1953 5 83 10990 372 1493 1951 4 86 10220 346 1493 1952 5 128 8770 293 1493 1953 5 105 10710 390 1493 1954 5 170 10910 373 1496 1952 5 100 12840 444 1496 1953 5 226 14490 474 1497 1953 5 212 13530 499 1498 1952 4 141 11930 416 1498 1953 5 189 13950 471 1499 1950 3 74 9530 342 1500 1951 4 218 13060 419 1500 1952 5 87 10280 315 1500 1953 5 118 11680 344 1500 1955 5 134 13710 391 1504 1952 5 122 12640 434 1504 1953 5 221 11210 405 1504 1954 5 125 12340 398 1505 1951 4 110 13570 436 1506 1953 5 267 11870 437 69

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

1506 1956 5 305 13750 471 1507 1951 3 126 11210 401 1507 1952 4 90 9690 317 1507 1953 5 99 10910 381 1507 1955 5 155 12770 4l8 1507 1956 5 131 14920 466 1508 1951 4 238 13340 395 1528 1951 3 85 9440 343 1528 1952 4 214 11780 371 1528 1953 5 106 10880 335 1528 1954 5 74 10310 339 1535 1951 3 113 876O 319 1535 1952 4 187 11560 407 1538 1952 4 121 13120 435 1538 1953 5 224 12990 450 1544 1951 3 133 12300 356 1544 1952 4 91 12120 399 1544 1953 5 194 9350 269 1549 1951 3 88 10900 359 1549 1952 4 216 13440 475 1549 1953 5 75 13350 473 1545 1951 3 116 12180 4ll 1545 1955 5 139 13010 4-54 1547 1952 4 181 12250 422 1552 1951 3 82 9950 355 1552 1952 4 109 9680 350 1553 1952 4 95 12940 450 1553 1953 5 94 12740 427 1553 1954 5 134 12390 4o4 1553 1955 5 97 13470 427 1553 1956 5 83 13620 433 1554 1951 3 235 11280 415 1555 1952 4 70 12570 432 1555 1956 5 111 13210 434 1558 1952 4 177 11530 357 1558 1953 5 149 11290 356 1559 1952 4 137 11620 365 1559 1953 5 115 10580 330 1560 1952 4 • 97 10750 363 1360 1953 5 102 12360 430 1560 1955 5 145 12980 433 70

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

1560 1956 5 83 13080 if 5 7 1562 1952 b 106 llif80 b 2 0 156if 1952 b 88 9760 3 b S 1566 1953 5 135 12210 if29 1568 1932 b 107 13590 if 8 7 1568 1953 5 157 12if80 ifif6 1568 1955 5 171 13230 if52 1568 1956 5 166 12020 if27 1571 1955 5 99 12ifl0 367 1571 1956 5 105 12ifl0 397 1574 1952 3 128 11580 if2if 157b 1953 b 76 9 b 2 Q 32if 157if 1954 5 2if8 l l b 60 if 32 1575 1952 3 7 b 8110 309 1577 1953 b 108 11230 ifOl 1577 1955 5 lif9 11750 390 1577 1956 5 165 13910 if 70 1582 1952 b 101 12350 396 1582 1953 5 96 12780 390 1583 1952 131 12080 if51 1585 1953 b 15^ 12520 if 6 3 1585 195^ 5 l8if 11660 if53 1585 1955 5 91 12360 if20 1585 1956 5 102 11270 377 1388 1952 4 13^ 13060 if28 1588 195^ 5 116 12990 if6o 1588 1955 5 106 lif070 50if 1588 1956 5 86 138if0 if93 1589 1953 5 179 16950 608 1589 1954 5 112 I69if0 5 7 b 1589 1956 5 216 I6if00 5 b 9 1596 1953 if 169 12510 ifif6 1596 195^ 5 101 15700 513 1596 1955 5 91 13700 if82 1596 1956 5 102 11670 if38 1599 1952 3 79 12010 if 18 1599 1953 if 86 11050 if02 1599 195b 5 89 11050 ifOO 1599 1955 5 190 13090 if82 1600 1952 3 135 11360 if27 1600 1953 if 78 9120 3if8 71

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

1600 1954 5 154 10040 396 1600 1955 5 75 8240 313 1600 1956 5 134 10460 396 1602 1953 4 157 12650 479 1602 1954 5 95 12850 462 1602 1956 5 91 10860 393 1603 1952 3 117 12330 415 1603 1953 4 126 11290 385 1603 1954 5 163 12770 409 1607 1953 4 92 12520 427 1609 1952 3 101 13070 451 1609 1953 4 90 12230 420 1609 1954 5 305 13330 453 1610 1953 4 171 13930 4 6 l 1613 1953 4 128 14450 495 1615 1952 4 115 12810 486 1625 1952 3 83 12810 420 1625 1953 4 155 13190 429 1625 1954 5 90 12430 430 1625 1955 5 81 13880 463 1625 1956 5 90 12980 424 1627 1952 3 192 13760 436 1627 1953 4 84 6790 262 1627 1954 5 139 12490 442 1632 1953 4 202 12020 424 1632 1954 5 69 12710 467 1632 1955 5 82 13660 487 1637 1952 3 128 12310 450 1637 1953 4 78 11030 422 1637 1954 5 76 11860 425 1637 1955 5 119 13000 466 1637 1956 5 116 11060 376 1640 1952 3 85 9250 309 l6 4 o 1953 4 100 l4 o 8 o 481 1642 1953 4 90 15420 546 1642 1955 5 81 15110 480 1644 1952 3 90 10930 396 1644 1953 4 110 11270 409 1644 1954 5 76 11310 417 1645 1954 5 134 9910 292 1648 1952 3 93 10540 316 72

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

1649 1953 4 176 11910 423 1649 1954 5 72 13670 481 1655 1952 3 81 12270 431 1655 1953 4 245 13140 4 8 l 1660 1953 4 101 13450 542 1660 1954 5 81 7820 296 1660 1955 5 78 13860 512 1660 1956 5 111 12680 485 1666 1952 3 189 13830 511 1666 1955 5 108 13490 492 1666 1956 5 181 11800 425 1674 1953 3 137 14110 536 1674 1956 5 164 8550 361 1675 1953 3 192 14220 572 1678 1953 3 74 11310 382 1683 1953 3 149 14840 530 1684 1954 4 101 11540 434 1686 1953 3 180 13760 471 1686 1956 5 132 14990 508 1687 1953 3 120 9570 355 1689 1953 3 130 9550 403 1689 1956 5 168 12790 497 1695 1953 3 80 13780 460 1695 1955 5 101 14010 497 1695 1956 5 305 14480 464 1703 1953 3 228 11970 384 1708 1953 3 80 9810 362 1708 1954 4 87 9940 353 1708 1955 5 109 11160 388 1708 1956 5 96 13390 454 1711 1953 3 112 13230 452 1711 1954 4 97 13990 495 1711 1955 5 136 11230 364 1713 1953 3 90 10580 387 1716 1954 4 151 11940 426 1716 1956 5 305 16240 6 l4 1717 1956 5 94 10690 357 1719 1956 5 87 15180 521 1720 1954 4 98 13380 512 1720 1955 5 88 13780 498 1720 1956 5 82 12340 422 73

TABLE 11 (Continued)

Cow No. Year Age Days Open Milk Butterfat

1723 1953 3 105 13030 441 1723 1954 4 97 11060 409 1724 1953 3 119 15860 533 1724 1954 4 50 13470 471 1724 1956 5 126 14510 544 1725 1954 4 118 13770 484 1731 1953 3 305 16540 6o4 1731 1956 5 305 15760 575 1735 1954 4 94 13200 501 1738 1954 3 94 12630 447 1743 1955 4 127 16350 558 1746 1955 4 82 10700 397 1746 1956 5 108 14400 462 17V? 19 55 4 117 12910 464 1747 1956 5 136 13520 498 1753 1955 4 91 14660 539 1754 1955 4 94 12810 417 175^ 1956 5 91 12960 516 1755 1954 3 114 13160 480 1757 1955 4 96 12280 438 1759 1954 3 86 12150 4 l8 1759 1955 4 92 11260 369 1759 1956 5 97 11080 397 1762 1955 4 118 15000 579 1766 1954 3 78 10360 370 1767 1954 3 149 15280 540 1767 1955 4 191 12590 449 1770 1954 3 98 13830 536 1770 1955 4 97 14680 547 1772 1954 3 100 11800 449 1772 1955 4 90 13780 523 1772 1956 5 125 12590 478 1776 1955 4 134 13640 515 1779 1955 4 127 12450 380 1783 1955 4 91 11350 371 1783 1956 5 140 13190 4 l? 1784 1954 3 82 11300 4o8 1785 1955 4 106 15500 577 1785 1956 5 98 14880 516 1789 1956 5 165 11910 4 l i 1791 1954 3 80 11680 383 ?4

TABLE 11 (Continued)

Cow No. Year Age Days Open 141 lk Butterfat

1791 1955 4 92 12920 461 1791 1956 5 102 12070 433 1794 1955 4 107 12070 437 1800 1954 3 155 14340 493 1800 1955 4 231 15140 367 1801 1955 3 91 10600 325 1803 1954 3 144 14890 543 1803 1955 4 110 15740 596 1804 1954 3 68 12920 449 1804 1956 5 124 12570 445 1806 1955 3 89 12780 492 1806 1956 4 167 13220 504 1808 1954 3 90 11930 457 1808 1953 4 88 12080 471 1813 1954 3 81 13920 518 1813 1956 5 86 12690 444 1817 1954 3 219 11780 381 1820 1954 3 93 9360 366 1820 1955 4 79 13620 468 1820 1956 5 100 10790 393 1828 1955 3 154 14290 486 1828 1956 4 110 14470 496 1829 1935 4 84 12990 457 1830 1955 3 116 11220 400 1832 1955 3 91 18450 656 1843 1955 3 92 13060 457 1845 1935 3 210 13410 500 1848 1956 4 119 14350 486 1853 1955 4 89 13490 467 1853 1956 5 91 11080 4o8 1853 1956 4 102 16480 627 1864 1955 3 106 13040 483 1864 1956 4 91 13010 496 1865 1955 3 100 16630 520 1868 1955 3 106 14120 554 1868 1956 4 109 12660 461 1870 1955 3 102 12170 419 1871 1955 3 84 11480 421 1871 1956 4 112 9730 344 1876 1956 3 91 15300 540 1876 1956 4 145 13670 486 75

TABLE 11 (Continued)

Cow No* Year Age Days Open M ilk Butterfat

1891 1955 3 96 130if0 it93 1898 1955 3 93 12680 3kk 1900 1956 if 97 10810 37* 1913 1956 3 105 13760 530 1925 19 55 3 106 13630 k67 1930 1956 3 122 1^570 535 1937 1956 3 105 17570 613 1938 1956 3 100 I 6190 538 1939 1956 3 97 1 3 ^ 0 449 19^0 1956 3 79 12330 if 70 19^5 1956 if 88 11780 ifl8 19^6 1956 3 112 10700 380 19^9 1956 3 86 13330 501 1950 1956 3 86 12830 if86 1951 1956 3 140 13*f90 if89 1957 1956 3 95 12250 if8l 1958 1956 3 172 135^0 iflif 1959 1956 3 257 13070 if6o 1962 1956 3 182 13MfO if86 1965 1956 3 102 8720 308 1969 1956 3 116 12if80 if56 1971 1956 3 305 12180 ififif 1973 1956 3 97 12350 ifif8 1975 1956 3 100 11370 381 1827 195^ 2 85 16260 575 TABLE 12

ORIGINAL DATA FROM THE TOLEDO HERD

Cow No. Year Age Days Open Milk Butterfat

416 1947 2 305 15180 460 420 1947 2 247 15070 530 424 1947 2 305 13940 460 434 1947 2 299 11210 337 4 36 1947 2 305 14800 520 b37 1947 2 305 10960 383 bbo 1947 2 305 11440 389 b b i 1947 2 33 11700 431 442 1947 2 96 13750 467 443 1947 2 305 14470 507 bbb - 1947 2 98 11860 4 l8 446 1947 2 207 13500 513 bb? 1947 2 222 11540 416 448 1947 2 305 13770 403 449 1947 2 279 12120 400 452 1947 ■ 2 305 13470 444 b3b 1947 2 45 9850 371 458 1947 2 158 13720 480 462 1947 2 163 15090 453 455 1948 2 305 17020 579 b37 1948 2 151 14170 454 b63 1948 2 152 11970 407 b6b 1948 2 177 14040 481 465 1948 2 149 11900 428 466 1948 2 305 10150 386 b67 1948 2 134 12010 468 468 1948 2 62 15220 503 469 1948 2 63 11830 426 b70 1948 2 225 15830 547 472 1948 2 120 15700 517 b7b 1948 2 65 14030 491 b77 1948 2 134 11480 425 482 1948 2 98 6670 227 486 1948 2 62 12240 443 487 1948 2 137 8030 394 490 1948 2 305 10340 4 l4 495 1948 2 83 8580 332 497 1948 2 4o 9980 347 504 1948 2 49 10190 365 500 1949 2 160 12460 399 15 1949 2 198 14580 527

76 77

TABU! 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

503 1949 2 189 ll8 4 o 344 505 1949 2 144 16730 535 507 1949 2 305 15430 506 509 1949 2 305 12890 488 510 1949 2 59 13990 474 511 1949 2 55 10570 356 515 1949 2 108 15640 56 5 517 1949 2 70 12690 489 518 1949 2 82 11220 381 519 1949 2 67 14170 459 521 1949 2 139 14870 485 522 1949 2 166 13430 439 526 1949 2 140 12760 433 527 1949 2 101 11560 377 528 1949 2 96 10070 366 530 1949 2 80 10590 398 531 1949 2 305 13580 460 532 1949 2 305 14780 507 534 1949 2 305 10860 413 537 1949 2 137 13950 480 540 1949 2 87 14110 478 5 4 l 1949 2 78 14550 493 542 1949 2 145 12170 365 543 1949 2 141 15410 492 544 1949 2 159 13690 478 545 1949 2 108 14730 532 547 19^9 2 122 13230 439 552 1949 2 87 16300 607 553 1949 2 146 13320 425 55^ 1949 2 123 10230 341 559 1949 2 170 10610 385 561 1950 2 305 12180 473 563 1949 2 56 13570 500 564 1949 2 305 13200 500 366 1949 2 199 11120 411 569 1949 2 183 10380 333 565 1950 2 142 11580 385 570 1950 2 229 15230 499 571 1950 2 279 15490 545 572 1950 2 305 15350 527 574 1950 2 168 13460 443 78

TABLE 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

575 1950 2 58 10980 400 576 1950 2 140 13040 416 578 1950 2 116 12620 477 580 1950 2 104 14840 502 581 1950 2 87 11720 355 583 1950 2 133 12330 418 584 1950 2 123 9260 360 586 1950 2 83 13440 436 587 1950 2 59 9390 364 589 1950 2 82 10640 369 590 1950 2 100 12140 430 592 1950 2 148 12200 377 594 1950 2 305 15510 564 596 1950 2 70 11780 467 597 1950 2 63 12680 486 601 1950 2 109 14320 496 602 1950 2 93 13590 433 6o4 1950 2 124 14900 548 605 1950 2 233 13770 412 607 1950 2 298 15860 506 609 1950 2 90 14440 464 610 1950 2 69 10880 389 611 1950 2 74 16630 583 613 1950 2 163 l6l4o 576 6l4 1950 2 305 14890 506 617 1950 2 71 18690 649 618 1950 2 110 13580 483 608 1951 2 234 16750 514 616 1951 2 49 12720 456 620 1951 2 305 14850 513 621 1951 2 162 15950 544 624 1951 2 96 15240 564 626 1951 2 100 13330 441 627 1951 2 86 11040 4l4 628 1951 2 64 12580 394 630 1951 2 65 12450 497 633 1951 2 106 15060 494 634 1951 2 305 14650 504 636 1951 2 74 15290 545 637 1951 2 50 13410 468 638 1951 2 67 16820 590 79

TABLE 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

639 1951 2 198 18960 701 642 1951 2 155 14690 646 643 1951 2 76 13930 479 644 1951 2 157 14320 588 645 1951 2 112 14030 467 649 1951 2 305 15030 525 650 1951 2 242 13310 434 654 1951 2 67 10960 353 655 1951 2 51 11290 4 i4 656 1951 2 127 12140 417 657 1951 2 121 11120 353 659 1951 2 70 12330 451 661 1951 2 67 11720 401 662 1951 2 89 14920 454 663 1951 2 35 8470 319 664 1951 2 134 14950 588 665 1951 2 156 11550 302 see 1951 2 102 14390 484 667 1951 2 65 12310 413 668 1951 2 66 16790 597 670 1951 2 224 13310 461 671 1951 2 70 11610 426 672 1951 2 104 IO650 387 675 1951 2 50 13300 423 678 1951 2 48 8390 306 680 1951 2 154 12320 411 681 1951 2 108 11780 405 682 1951 2 52 14190 441 683 1951 2 50 13380 417 685 1951 2 63 13170 4 l8 688 1951 2 82 12560 392 689 1951 2 230 15050 437 696 1951 2 57 11820 368 686 1952 2 145 14730 440 690 1932 2 305 19250 649 691 1952 2 131 14240 491 693 1952 2 95 12650 44o 700 1952 2 242 13980 410 701 1932 2 64 9780 3^6 702 1952 2 192 12600 376 703 1952 2 54 11950 374 8o

TABLE 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

704 1952 2 173 16490 535 705 1952 2 71 13990 441 706 1952 2 130 12670 440 707 1952 2 172 12040 401 709 1952 2 71 11460 4o4 710 1952 2 243 14790 513 711 1952 2 62 12510 461 713 1952 2 110 13500 438 714 1952 2 60 16620 569 716 1952 2 98 10790 397 717 1952 2 121 12160 432 723 1952 2 247 12980 442 725 1952 2 204 12290 429 728 1952 2 91 14140 441 730 1952 2 66 9510 309 731 1952 2 57 9820 311 732 1952 2 71 11070 390 734 1952 2 96 11910 382 735 1952 2 64 14360 461 736 1952 2 81 12800 413 740 1952 2 65 14000 485 743 1952 2 79 12270 388 744 1952 2 110 15730 534 746 1952 2 305 14480 496 749 1952 2 114 14430 545 752 1952 2 83 14450 593 741 1953 2 78 14060 552 750 1953 2 69 13410 438 751 1953 2 136 12610 450 754 1953 2 53 13110 458 755 1953 2 68 11830 426 758 1953 2 52 13380 499 760 1953 2 69 7260 277 761 1953 2 122 14260 554 763 1953 2 56 11530 433 766 1953 2 159 15360 537 768 1953 2 130 13290 521 769 1953 2 51 15500 545 770 1953 2 212 16500 660 774 1953 2 107 15460 478 778 1953 2 104 15240 563 81

TABLE 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

782 1953 2 113 11790 427 786 1953 2 95 14430 471 788 1953 2 188 11840 452 790 1953 2 94 15620 613 795 1953 2 116 13660 461 796 1953 2 165 13210 412 797 1953 2 70 9830 339 798 1953 2 106 14850 533 799 1953 2 120 14160 533 800 1953 2 60 11310 385 801 1953 2 85 15660 594 802 1953 2 48 12760 477 803 1953 2 101 9560 383 804 1953 2 108 12750 385 805 1953 2 78 14640 550 806 1953 2 138 14730 555 807 1953 2 92 15530 618 808 1953 2 201 13500 495 809 1953 2 113 13170 464 814 1953 2 85 13490 493 817 1953 2 100 14100 486 818 1953 2 132 14220 470 813 1954 2 98 11600 400 815 1954 2 108 14830 491 820 1954 2 108 12950 483 821 1954 2 184 13240 449 823 1954 2 291 13800 454 824 1954 2 88 15420 579 827 1954 2 72 13o00 524 828 1954 2 122 13310 499 830 1954 2 61 15890 636 831 1954 2 200 15240 596 832 1954 2 99 11670 489 833 1954 2 132 16050 603 834 1954 2 178 17780 608 836 1954 2 305 13640 473 837 1954 2 99 l4 l 6 o 538 838 1954 2 124 16460 546 839 1954 2 135 13540 457 840 1954 2 112 13940 511 8 4 l 1954 2 76 14700 500 82

TABLE 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

843 1954 2 148 12720 483 845 1954 2 110 13790 489 847 1954 2 125 13020 505 848 1954 2 140 12480 403 849 1954 2 79 10940 425 850 1954 2 99 11210 341 851 1954 2 83 12590 530 853 1954 2 76 9320 371 854 1954 2 194 14440 526 855 1954 2 122 11590 420 856 1954 2 85 12530 500 858 1954 2 89 12760 423 859 1954 2 289 9470 351 860 1954 2 98 13200 452 861 1954 2 93 11270 425 863 1954 2 106 10730 377 864 1954 2 86 12650 4o4 865 1954 2 80 10190 370 867 1954 2 85 13570 516 868 1954 2 83 11660 4 l4 869 1954 2 171 9720 357 870 1954 2 81 10980 385 871 1954 2 93 8930 364 872 1954 2 79 9550 349 874 1954 2 91 10620 398 875 1954 2 170 12150 426 877 1954 2 170 10400 341 876 1954 2 181 11060 340 878 1954 2 305 11320 432 881 1954 2 75 10350 362 882 1954 2 133 14490 504 883 1954 2 135 11520 386 884 1954 2 77 10570 368 886 1954 2 156 12200 554 887 1954 2 204 14490 578 891 1954 2 184 11180 388 892 1954 2 136 11910 456 893 1954 2 146 12160 459 896 1954 2 56 7460 291 901 1954 2 83 11780 435 900 1954 2 134 11160 398 83

TABLE 12 (Continued)

Cow No. Tear Age Days Open Milk Butterfat

902 1954 2 120 14680 525 903 1954 2 83 11580 410 906 1954 2 106 9030 303 90 7 1954 2 86 11170 383 910 1954 2 138 13640 516 913 1954 2 133 12900 459 899 1955 2 303 14800 506 903 1955 2 202 13010 491 908 1955 2 89 12810 488.. 911 1955 2 75 11850 497 912 1955 2 138 13250 451 914 1955 2 87 11430 403 916 1955 2 202 12390 439 917 1955 2 75 11600 479 919 1955 2 76 13120 498 921 19 55 2 169 13450 581 922 1955 2 175 13700 500 923 1955 2 305 13230 449 924 1955 2 291 13580 434 926 1955 2 291 12290 398 928 1955 2 234 9600 402 927 1955 2 305 8470 265 930 1955 2 305 12970 522 935 1955 2 86 15030 539 937 1955 2 177 11910 366 938 1955 2 148 10850 538 940 1955 2 183 10780 441 941 1955 2 207 11280 ^33 942 1955 2 182 14950 577 943 1955 2 16? 14050 504 947 1955 2 70 10170 423 950 1955 2 126 11810 437 953 < 19 55 2 146 13690 506 957 1955 2 301 16360 534 959 1955 2 115 13820 520 961 1955 2 178 17240 522 967 1955 2 114 14510 509 978 1955 2 108 9630 348 980 1956 2 118 15840 560 981 1955 2 112 11170 456 984 1955 2 115 15910 531 TABLE 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

986 1955 2 123 14860 476 990 1955 2 80 19770 685 989 1956 2 175 19150 657 997 1956 2 107 12530 399 999 1956 2 184 14770 492 1000 1956 2 84 14930 513 1 1956 2 305 14480 468 9004 1956 2 182 20890 638 9007 1956 2 88 16380 584 9009 1956 2 115 13560 528 9013 1956 2 91 12490 4 l6 9014 1936 2 83 14100 540 9018 1956 2 90 16340 557 9027 1956 2 248 12630 477 9029 1956 2 229 14280 533 9030 1956 2 139 13410 465 9032 1956 2 82 14470 582 9034 1956 2 305 16360 544 9043 1956 2 136 11180 439 9045 1956 2 305 14460 528 9049 1956 2 119 15010 582 9051 1956 2 297 13470 520 9053 1956 2 148 15970 589 9034 1956 2 81 14570 519 9063 1956 2 279 15820 518 9068 1956 2 116 17890 580 9070 1956 2 75 14650 550 9073 1956 2 153 13060 439 9076 1956 2 161 18690 717 9077 1956 2 79 13650 514 9078 1956 2 86 17470 521 9079 1956 2 111 11060 415 9083 1956 2 86 15590 585 9090 1956 2 74 15520 574 415 1949 4 78 12520 415 416 1950 5 71 16650 573 420 1950 5 79 15340 555 420 1951 5 106 12810 440 420 1952 5 113 11140 392 432 1949 4 105 11410 400 434 1950 5 118 13800 439 85

TABLE 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

434 1951 5 132 l4o6o 437 434 1953 5 286 12050 385 434 1954 5 58 9450 300 436 1950 5 99 9760 379 436 1951 5 117 11010 383 436 1952 5 171 10050 333 441 1951 5 66 10400 343 441 1953 5 154 18700 684 441 1955 5 98 15490 560 448 1950 4 188 9900 333 448 1953 5 123 11570 349 451 1950 4 186 12970 521 454 1951 5 140 13350 515 454 1952 5 92 10070 429 454 1953 5 146 12280 481 457 1949 3 129 12090 447 461 1949 4 87 13550 446 464 1951 5 227 13180 422 464 1953 5 258 12450 438 465 1949 3 69 11820 424 469 1949 3 78 10790 400 470 1949 3 129 14050 528 470 1953 5 214 11920 425 472 1949 3 95 14740 494 472 1950 4 102 10100 337 477 1950 4 116 7530 282 484 1949 3 196 11100 401 484 1951 5 56 8200 303 485 1953 5 244 11930 453 486 1949 3 186 11030 419 486 1950 4 90 11860 423 486 1951 5 94 9980 4l4 487 1949 3 236 10920 427 497 1949 3 93 10660 389 497 1951 5 181 11390 409 497 1953 5 52 8330 288 15 1953 5 78 8400 317 15 1950 3 123 12600 414 15 1952 4 82 12320 444 279 1953 5 61 14710 491 279 1950 5 178 15070 464 86

TABLE 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

504 1952 5 101 14280 460 504 1949 3 75 10490 410 504 1950 4 182 9040 341 504 1952 5 65 9570 340 504 1953 5 152 10940 430 510 1949 3 107 10370 362 510 1952 5 71 10280 361 514 1950 3 62 11750 427 514 1951 4 68 7970 278 515 1950 3 131 12260 452 515 1951 4.. 54 12040 423 515 1952 5 179 11740 435 518 1950 3 61 11960 425 518 1951 4 80 11560 4o4 518 1952 5 75 12280 398 518 1952 5 148 9400 347 519 1950 3 305 14010 473 519 1951 5 127 11980 425 521 1950 3 305 14000 481 521 1952 5 204 12660 420 521 1953 5 113 11690 405 528 1951 4 132 7290 261 530 1950 3 296 10820 396 530 1952 5 100 11640 447 530 1954 5 212 10730 423 533 1951 4 87 9950 341 533 1952 5 57 9000 301 533 1953 5 119 9800 327 536 1951 4 154 13350 473 537 1950 3 154 12620 418 537 1952 4 64 11190 388 537 1952 5 85 12160 420 538 1952 5 283 12400 386 539 1951 4 239 8370 273 539 1952 5 108 11440 396 539 1954 5 106 12460 449 539 1955 5 55 6500 215 541 1950 3 176 8200 270 541 1951 4 128 12240 412 541 1952 5 69 9690 345 542 1950 ■ 3 53 12780 430 87

TABLE 12 (Continued)

Cow Ho. Year Age Days Open Milk Butterfat

542 1951 4 77 10580 366 5 *+2 1952 5 51 10340 367 545 1950 3 82 12830 464 5^7 1950 3 96 11440 330 54? 1951 4 175 9950 324 547 1953 5 59 5260 151 552 1950 3 112 8610 327 552 1951 4 151 11060 405 552 1953 5 1^3 l4 i6 o 514 559 1951 3 259 10320 367 563 1950 3 145 11110 4o6 563 1951 4 115 10130 365 566 1951 3 212 12060 4 l4 566 1952 5 72 9690 343 566 1953 5 76 9060 303 570 1951 3 77 8940 283 571 1951 3 144 12380 409 571 1952 5 100 11730 428 57^ 1951 3 190 12870 39^ 576 1951 3 57 10180 315 576 1952 4 93 9680 328 578 1952 4 62 7580 287 579 1952 4 90 93^0 342 579 1953 5 47 8580 339 581 1951 3 66 15270 501 581 1952 4 233 12890 448 588 1952 4 110 7930 275 589 1951 3 70 8440 276 589 1952 4 65 8000 269 589 1953 5 63 6 l4 o 222 590 1951 3 95 11370 421 590 1952 4 81 8970 325 590 1953 5 56 5790 212 592 1951 3 61 13210 403 596 1951 3 174 9910 396 596 1952 4 91 10740 445 596 1953 5 118 9300 4 l8 597 1951 3 145 9300 329 597 1952 4 107 10920 395 597 1953 5 74 9120 385 6o4 1951 3 98 12760 442 88

TABLE 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

6o4 1953 4 74 12120 449 6o4 1953 5 92 11600 415 604 195^ 5 116 12510 480 604 1956 5 120 13120 51^ 6o 6 1952 3 153 13830 460 606 1953 4 168 8680 284 606 195^ 5 120 9490 326 607 1952 3 201 8600 325 608 1952 3 134 16170 531 608 195^ 5 133 13400 467 608 1955 3 77 12180 400 609 1951 3 305 16570 580 609 195^ 5 86 12340 415 609 1955 5 190 17190 531 610 1951 3 167 11470 422 611 1951 3 94 15050 489 611 1953 3 105 11900 421 611 195^ 5 135 136OO 503 613 1952 3 125 16090 591 6 i4 1953 4 305 11730 ^59 616 • 1952 3 80 12630 435 618 1952 3 70 10750 382 620 1952 3 63 10650 387 620 1953 4 168 10400 380 620 195^ 5 67 10340 382 620 1955 5 171 14210 509 623 1952 ✓ 56 6720 223 624 1952 3 239 15040 6 l4 624 1953 4 88 11930 496 626 1953 4 157 10070 346 628 1952 3 85 7350 237 630 1952 3 89 11690 433 630 1953 4 71 8610 370 633 1952 3 45 12770 394 633 1953 4 189 12180 436 633 1935 5 91 13400 430 637 1952 3 222 11590 389 637 1953 4 93 9720 359 638 1952 3 210 13280 488 639 1952 3 81 12000 412 639 1953 4 124 li 4 4 o 389 89

TABLE 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

643 1952 3 89 10290 314 643 1953 4 54 9060 296 643 195^ 3 88 8770 300 644 1952 3 212 12950 488 645 1952 3 85 10140 327 645 1953 4 62 11820 426 645 1954 5 126 11530 387 649 1953 4 65 13410 484 650 1952 3 155 12580 430 650 1954 4 124 10780 360 650 1955 5 193 11840 388 655 1952 3 52 11680 340 655 1953 4 161 9080 309 655 1954 5 167 10170 369 659 1952 3 73 9710 383 661 1952 3 147 14240 469 661 1953 4 57 10900 384 661 1954 5 170 13030 467 664 1952 3 140 13500 548 665 1952 3 142 8360 233 667 1952 3 82 11180 349 667 1953 4 89 6740 233 667 195^ 3 135 10760 363 668 1952 3 92 15520 517 668 1953 4 182 10970 383 666 1952 3 87 14230 474 666 1935 5 118 12850 448 666 1956 5 95 15230 539 671 1952 3 71 10320 350 671 1953 4 59 10980 360 671 195^ 5 160 8670 302 675 1952 3 54 15230 500 675 1953 4 119 15230 501 675 195^ 5 103 10300 359 675 1935 5 88 15560 545 675 1956 5 305 17620 620 678 1952 3 67 8360 288 678 1953 4 59 6010 224 681 1952 3 73 10100 332 681 1953 4 83 9610 338 682 1932 3 58 12110 384 90

TABLE 12 (Continued)

Cow No. Tear Age Days Open Milk Butterfat

686 1953 3 236 16580 514 690 1954 4 305 12020 398 691 1953 3 148 16290 615 691 1954 4 121 13560 502 696 1954 4 170 15500 505 696 1955 5 305 13000 454 700 1953 3 102 12780 403 700 1954 4 89 10400 323 700 1956 5 172 12250 4 l4 701 1953 3 72 7310 286 701 1954 4 107 10930 421 701 1955 5 106 9640 371 701 1956 5 196 13950 565 702 1953 3 45 9380 277 702 1954 4 84 8580 251 703 1953 3 103 10330 362 703 1954 4 305 9810 346 704 1953 3 121 12290 411 704 1954 4 87 11850 439 705 1953 3 143 16080 488 710 1953 3 180 9710 342 710 1954 4 78 8110 313 711 1953 3 63 13620 535 713 1953 3 81 12040 386 714 1953 3 152 16910 527 714 1954 4 121 10700 354 717 1953 3 143 11680 410 717 1954 4 101 8190 279 717 1955 5 120 10890 400 717 1956 5 196 12730 472 723 1954 3 152 10280 374 723 1955 4 214 9650 339 723 1956 5 92 14840 524 731 1953 3 96 8030 284 732 1953 3 109 10810 395 735 1953 3 289 11750 395 735 1955 4 98 11870 407 736 1953 3 243 13540 420 736 1955 4 96 5980 205 741 1954 3 167 11100 444 741 1956 5 109 7490 345 91

TABLE 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

743 1953 3 l 4 l 14210 443 743 1955 4 110 10360 345 744 1953 3 74 12770 432 746 1954 3 91 11180 419 746 1954 4 106 9040 304 749 1953 3 86 12290 470 749 1954 4 94 10060 354 749 1955 5 49 9110 4 o i 750 1954 3 130 15230 495 750 1956 5 169 14800 467 751 1954 3 169 12160 399 752 1953 3 216 11440 467 754 1953 3 77 7430 290 755 1954 3 158 14290 515 758 1953 3 73 7680 290 758 1954 4 107 9750 368 763 1954 3 178 11500 419 766 1954 3 78 12230 426 778 1955 4 72 10590 396 786 1954 3 121 11790 409 786 1955 4 79 13220 466 786 1956 5 103 13220 439 788 1954 3 146 13260 506 790 1955 4 145 13650 512 799 1954 3 104 12830 533 799 1955 4 78 10220 388 803 1954 3 106 11180 430 803 1955 4 129 10410 420 806 1955 3 122 10960 417 808 1955 3 106 12570 456 815 1955 3 274 14550 489 815 1956 4 109 13080 412 818 1955 3 82 12840 436 818 1956 4 72 11240 356 818 1956 5 80 12340 394 820 1955 3 85 9440 362 823 1955 3 90 6730 216 831 1955 3 247 14480 635 831 1956 5 221 15410 618 832 1955 3 198 9790 371 832 1956 4 168 8560 323 92

TABLE 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

834 1955 3 305 15350 525 834 1956 5 124 13940 506 836 1955 4 250 16020 551 837 19 55 3 161 13530 522 837 1956 4 139 16700 631 838 1955 3 197 15240 577 838 1956 4 305 13070 464 839 1955 3 93 11890 440 839 1956 4 215 14170 493 8 4 l 1955 3 191 10380 389 843 1955 3 156 13130 506 843 1956 4 92 11320 419 847 1955 3 121 12830 500 849 1955 3 305 11770 495 850 1955 3 91 9660 313 850 1956 4 80 9650 320 851 1956 4 91 14410 634 854 1955 3 147 14070 503 855 19 55 3 78 10500 377 856 1955 3 106 11490 510 856 1956 4 175 13390 542 858 1955 3 77 11990 406 859 1956 3 83 14430 592 861 1956 4 95 9230 380 867 1955 3 108 11350 445 868 1955 3 82 12650 461 868 1956 4 74 14040 497 876 1955 3 93 13740 482 877 1955 3 95 8790 302 882 1955 3 111 9590 348 883 1955 3 107 14470 482 884 1956 4 110 13970 534 892 1955 3 127 15120 597 900 1956 4 178 10850 401 903 1956 4 130 11500 4l8 905 1955 3 115 12840 471 905 1956 4 88 13550 519 907 1955 3 267 14540 491 914 1956 3 115 13320 501 924 1956 3 140 14010 4l6 926 1956 3 94 13760 486 93

TABLE 12 (Continued)

Cow No. Year Age Days Open Milk Butterfat

928 1956 3 78 10440 440 935 1956 3 121 14870 527 940 1956 3 104 11940 512 9 b 7 1956 3 84 15140 574 953 1956 3 131 12560 447 961 1956 3 88 16800 489 AUTOBIOGRAPHY

I, William Mathias Etgen, was born in Toledo, Ohio, May 7i

1929. I received my primary and secondary education in the Ft.

Jennings Consolidated Schools at Ft. Jennings, Ohio, and my undergraduate training at Ohio State University, which granted me the Bachelor of Science degree in Agriculture in 1951* In

195*+, after working one year as herdsman and two years as farm manager of a large dairy farm in Wisconsin, I returned to Ohio

State University where I received a Master of Science degree in

1955* In the same year I obtained an appointment to assist in research in the Ohio North Central Dairy Cattle Breeding

Project, a position I held for three years while completing the requirements for the Doctor of Philosophy degree in the Depart­ ment of Dairy Science.

9^