Breeding Livestock Adapted to Unfavorable Environments

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BREEDING LIVESTOCK adapted to UFFAVORABLE ENVIEZO MENTS

Washington, U.S.A. August 1949 OTHER FAO AGRICULTURAL STUDIES

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The pattern of economic livestock production in any area is determined largely by the environment. Here, in eastern Utah (U.S.A.), a herd of range sheep is being trailed from summer range at high elevations to lower areas vvhere the sheep will be grazed during the autumn, winter, and spring.

Photo by Bureau of Land Management, U. S. Department of the Interior. FAO Agricultural Studies No. 1

r).:,,NG LIVES

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ENVIRONM TS

An FAO Study Prepared by RALPH W. PHILLIPS Chief, Animal Industry Branch and Deputy Director Agriculture Division

Washington, U.S.A. August 1949 FirstprintingJanuary1948 Second printing August 1949 CONTENTS

Introduction 1

Conversion Table for Weights and Measures

Geographic and Climatic Limitations upon Livestock Production 5

Adaptability of Sheep to Various Environments 15 Stratification of the Sheep Industry in Great Britain 15 Performance of Columbia Sheep in Two Environments 27 Reactions of Various Breeds of Sheep to High Temperatures 35 Observations on Adaptability of Sheep. in China 36 Improving Deccan Sheep by Selection and Grading Up with Merinos 44

Reactions of Southdovvn Sheep to Two Environments . 47

Experience with the Introduction of Sheep in Iceland . 52 Improvement of Navalo Indian Sheep 59 Improvement of Native Sheep in Egypt 64

Adaptability of Cattle to Tropical and Subtropical Climates 67 Adaptability as Measured by Milk Production 81 Adaptability as Measured by Beef Production 84 Observations In Northern Australia 89 Observations in Jamaica and Trinidad 91 Results in Tunisia 98 Development of the Santa Gertrudis Breed in Southern Texas, U.S.A. 99 Work in South Africa 103

Observations on Adaptability of Horses and Swine 107 Adaptability in Horses 107 Adaptability in Swine 114

Use of Less-Known Types of Animals in Livestock Production 133 Water Buffaloes 133 Yaks 138 Reindeer 141 Camels and Dromedaries 145 Llamas and Alpacas 146 Methods of Breeding 153 Selection 154 Inbreeding 163 Crossing 168 Developing New Breeds 171 Reproduction 173 Hybridization 173

Improving the Environment 174

Conclusion 175

Literature Cited 177

vi 1 I RODUCTIO Animals differ widely in their ability to thrive and to perform efficiently under a given set of conditions. Some animals are adapted to cold climates, others to temperate climates, still others are more suited to tropical conditions. Certain types of animals, such as the yak and vicuna, thrive at high altitudes, while others cannot survive satisfactorily there. Animalsvary also in their grazing ability. Some can obtain a satisfactorily living while grazingover extensive range lands, while others require lush pastures and supplementary feeding if they are to perform efficiently. Animals vary also in their adaptability to conditions withina given climatic zone. In the temperate zone, for example, some are able to utilize areas of sparse grazing and are thus able to harvest extensive areas of land that would otherwise be of little use to man. They can thus turn forage into products that are of great importance. Such animals are often limited in their productive capacities when placed under excellent environmental conditions. Theyare able to live and reproduce quite satisfactorily, but they have been 0:-veloped under conditions where natural selection eliminated the weaklings, and where there was relatively little opportunity for expression of, and selection for, superior milk, meat, or fiber production. Thus, under good environmental conditions, itis necessary to select stock that has the inherent capacity to utilize efficiently large amounts of good-quality feed, if that feed is to be transformed most effectively into products for human consumption. A few examples will illustrate some of the differences. The Holstein-Friesian breed of cattle was developed in the temperate zone and under conditions of intensive farming. It is well adapted to areas where pastures are good, where itispossible to grow ample supplemental feed, and where there is a market for a sizeable volume of milk. But it is not suited to many areas in the tropics or to areas of scanty feed in the temperate zones. By contrast, the yak is admirably suited to high elevations and extensive grazing condi. tions such as are found on the Tibetan highlands of Central Asia, but it does not produce at a sufficiently high level to use large amounts of good-quality feed efficiently.Still another contrasting type may be found in the water buffalo. This animal is adapted to tropical conditions; andsome breeds, such as the Murrah of India, produce reasonably good quantities of milk while being fed coarse roughage and limited amounts of other feed under tropicalcli- matic conditions that adversely affect Holstein cattle. Neither the yak nor the water buffalo would be suited to areas where intensive dairying is practiced, such as the Netherlands, or Wisconsin and New York states in the United States of America, for they are not adapted

1 to the climatic and other conditions prevailing there, and do not have sufficient inherent milk-producing capacitytoutilizethe available feedefficiently. On the other hand, the Holstein-Friesian, and other highly specialized dairy breeds developed under similar conditions, cannot perform satisfactorily and often are unable to survive under conditions where the yak and the water buffalo can thrive. The variations in adaptability among highly specialized dairy cattle, yaks, and water buffaloes are quite extreme. Similar examples of extreme variations may be found in other classes of livestock. The Rambouillet sheep is able to find a livelihood on the extensive range lands of the western United States of America, and its close relative, the Merino, makes effective use of the extensive grazing areas of Australia, where grazingisalsosparse,a.nd where severe droughts often occur. On the other hand, the Hampshire, Shropshire, and other mutton breeds are better suited to the pastures of the Corn Belt in the United States and to the Dovvn regions of southern England. Still other types, such as the Welsh A/fountain and the Blackfaced Highland, are suited to the rugged environment of the highlands of Wales and Scot- land, where the climate is cold and damp, and where grazing is generally sparse. But there are less apparent variations, even among types and breeds that have been developed under rather similar conditions, thatmay be of considerable importance in determining thesuccess with which anirnals of a given type may be used under a certain set of conditions. It has been demo.n- strated,for example, that Jerseycattle have greater heat tolerance than Holstein-Friesian cattle and are therefore lessaffected by the subtropical conditions that prevail in the Gulf Coast region of the United States during the summer months (Seath and Miller, 1947). Variations in adaptability are important in selecting stock for a given set of conditions. This point has been frequently overlooked in attempts to improve the quality or productivity of stock in a givenarea. This has been particularly truein underdeveloped countries or regions, where rigorous enVironmental conditions prevail, andas a result much time, effort, and money have been expended, often withvery disappointing results. Similar failures have been observed in well-developed countries, in sections where the Climate is rigorous or where feed isscarce. Relatively little attention has been given in animal breeding to variations in adaptability. The reason is, partially, in the way higher education and experi- mentation in animal husbandry have developed. Animal husbandry and other branches of agriculture have naturally grown most rapidly in countries having optimum or near:optimum conditionsforagriculturalproduction.Such countries have been in the best position, financially,to promote. agricultural research and teaching, and their outstanding institutions have generally developed in regions adapted to intensive agriculture. It has naturally followed that the majority of leaders in animal husbandry have devoted their attention to areas where 'adaptability to rigorous conditions is of minor importance. And these leaders have taught most of the students from underdeveloped countries, which are without adequate institutions of theirown. These students have rarely had their attention called to the problems of adaptability thatmust be dealt with in their own countries; in few cases have they been givenany real appreciation of how to deal with these problems'. It is not surprising, then, to find many cases in which these students, returning to their own countries as leaders, have attempted to import stock that was near ideal in the area where they received their training, but whichwas ill-suited or entirely unadapted to the conditions to which itwas taken. Livestock play an important part in agricultural production in most parts of the world. They supply much of the draft power on farms, and transform rough feed into manure thatisessential for maintenance of soilfertility. They atso supply milk, meat, skin, and fibers, without which man could not be adequately fed and clothed. Human welfare demands that livestock function with maximum efficiency. To accomplish this, the adaptability of animals to the environment under which they live and produce must be given careful consideration in all attempts to expand and improve livestock production. This volume has been prepared to call attention to the importance of this problem of adaptability. It summarizes important work that has been done in various parts of the world to determine the reactions of animals to their environment and to develop animals adapted tospecific conditions. The inherent or genetic adaptability of animals to various environments is stressed. Obviously, the productivity of animals can also be improved by providing a better environment, for the performance of any animal is determined partially by its hereditary make-up and partially by the conditions under which it is developed and maintained. But, in many areas, limitations are laid down by nature. The livestock prodUcer may progress only to a certain point in improving, within economic limits, the supply of feed and other environmental factors. In tropical and subtropical areas, many of the conditions under which cattle must be produced are determined by nature. if a producer's cattle are to perform profitably, he rnust select and breed animals that are adapted to the environment. This is equally true of vast semiarid regions, high mountain and plateau regions, subarctic areas, wet hill country such as the highlands of Scotland and Wales, and other areas where the first measure of an animal's performance is its ability to survive.

3 CONVERSION TABLE FOR WEIGHTS AND MEASURES (This partial list of weight and measure equivalents is included for the use of readers who may wish to convert from one system of weights and measures to another.) Length 1 centimeter 0.3937 inchl 1 meter 3.281 feeti 1 kilometer 0.621 milel 1 inch 2.540 centimeters 1 foot 0.3048 meter 1 mile 1.609 kilometers 1 Chinese foot 1/3 meter

Weight 1 kilogram 2.205 pounds 1 metric ton 1.102 short tons 1 metric ton 0.9842 long tons 1 pound 0.4536 kilograms 1 short ton 0.9072 metric tons 1 long ton 1.016 metric tons 1 catty 1/2 kilo

1 Inches, feet, and miles are U.S.A.-British units.

4 GEOGRAPHIC ,N ) CLIMATIC LIMIT/ VESTOCE ')1'101DUCT/C

Much attention is being given to the agricultural problems of the world, to ensure that the people of the world are adequately fed, clothed, and housed. The magnitude of the work that must be done to accomplish this worthy objective is apparent to all who are familiar with the many problems involved in producing and distributing the products of the farm and ranch. It is natural, in considering these problems, that attention should be focused on the areas where agricultural production is most intensive, such as the rice-producing regions of China and India, the fertile fields of Denmark, and the Corn Belt of the United States of America. One important fact, often overlooked, is that only a relatively small portion of the world's land area is devoted to intensive farming. This fact is illustrated graphically in Figure 1,1 the map of the major land areas of the world. Examination of this map reveals, even to the casual reader, the relatively small proportion of land devoted to comparatively intensive agriculture (areas E, F, G, H, I, J, K, L, and irrigated land), the large proportion devoted to extensive agriculture (areas A, B, C, and D); and the vast extent of the land that is not producing any usable agricultural products. Much of the land in the latter areas is desert, tropical jungle, and frozen tundra; there islittle reasonabk chance of using most of it for agricultural production. Some portions of this area might be made productive. There are many tracts in areas now devoted to extensive agriculture that might be turned to intensive production through irrigation, drainage, and other means. However, the amount of such land is relatively small, compared to the total land area. Obviously, the areas of intensive farming are of major importance in producing the world's food supply. There is no intention here to minimize their importance. However, the areas of extensive production should not be under- estimated: they are the sources of a considerable proportion of the world's supply of animal protein, hides, and animal fiber. They also provide many of the animals that are used for power and for fattening as meat in the areas of intensive farming. The discussion in this volume is directed to the areas of extensive agricul-

This map appeared in the United States Department of Agriculture Yearbook of Agriculture for 1941, entitled Climate and Man.

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Ay- A EN WET LEGEND setmAnto ED fi TAIRA 1111111 PERPETUAL FROST A V C 0,t Figure 2. Distribution of principal climates of the earth. ture, particularly those where environmental conditions are rigorous, and to areas of intensive auiculture vvhere tropical and other conditionsplace limitations on animal production. Many factors determine the productive capacity of an area, apart from the basic physical factors of soil composition, elevation, latitude, and slope. These include precipitation, temperature, evaporation, sunshine, cloudiness, and fog, all of which combine to make up the climate ofan area. It is possible to define more or less definite climatic regions in the world, and theseare shown on the map in Figure 2.2 Actually the boundaries shift from year to year, the regions themselves expanding or contracting, and these shiftsare of critical importance in agriculture. FIowever, the mean position of the climatic regions is most strongly related to the distribution of natural vegetation and soils and the development of minor land forms (Blumenstock and Thornthwaite, 1941). There is a close relationship between vegetation and climate, and many terms have come into use to describe both climate and vegetation. The word "desert" calls to mind a region which is excessively dry, characterized by sparse vegetation. "Steppe" is a term at once descriptive of semiarid climate and of short-grass vegetation. "Tundra" applies to those cold subarctic lands, frozen much of the year, where only mosses, lichens, and occasional stunted trees grow. Many other terms apply interchangeably to climate and vegetation. The close relationship between climate and vegetation is a natural conse- quence of thousands of centuries of plant differentiation and adaptation. The closeness of this association can he seen by comparing the map of the distribution of principal vegetative formations shown in Figure 3 3 with that for climatic regions shown in Figure 2. The distinct differences in the environments to which animals are subjected in various parts of the world are brought out dramatically in these two maps: animals must feed upon the vegetation, and they must be able to withstand the climate unless special shelter is provided. Temperature is one of the important factors influencing the ability of animals to survive without shelter in a given area, either because of extreme heat or extreme cold. Maps presented in Figures 4 and 5 4 show isotherms for January and July, the months at which extremes of temperature are generally most apt to occur.

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Figure 4. January isotherms (lines of equal temperature135 around the 120 105 90 75 GO 4 15 15 o45 earih). Average January temperatures (CF.). SO 75 0 1115 45 60 75 90 105 120 135 150 temperaturesvariationsfiguresFigure 45. and may (°F.). 5, be that due wide to differences variations inin topography July isotherms (lines of equal temperature 120 105 90 75 temperature 15or elevation;aroundare encountered thethey earth). cannot Readers frequentlybe shown should overin small-scale comparativelybear in mind,0 small 15 30 45 60 75 90 105 120 135 maps. Averagein connection July withareas. Such local150 165 180 In view of the limitations placed on livestock production by environmental conditions in many parts of the world, itis essential, when plans are made for the improvement of livestock production, that careful consideration be given to adaptability of animals to these conditions. This problem,or group of problems, has not been given the attention it deserves in research and applied programs. In recent years, however, sufficient work has been carried out to serve as a guide in planning livestock development in some areas, and in planning future work on problems of adaptability.

Figure 6. Brown hairy sheep of southern India. These lean, long-legged animals are able to cover large areas in their search for food, and their light coat of hair makes them better suited to a tropical climate than would a wool coat.

Many types of sheep are found in different parts of the world, and they are adapted to a wide variety of conditions. Some of this -variation in adaptability has resulted from selection by man, while other types of variation have no doubt resulted from the rigorous selection imposed by nature. Examples of extremes in adaptability are the brown hairy sheep of southern India, the Blackfaced Highland sheep of Scotland, and the Hampshire sheep of England. The brown hairy sheep (Fig. 6)is adapted to the hot and relatively dry country of southern India. It has only a short coat of hair and, while itis not highly specialized for mutton production, itisable to withstand the climatic conditions under which itis produced. The Blackfaced Highland (Fig. 7) is adapted to the cold, wet highlands of Scotland, where sheep must live and produce under extensive grazing conditions and where the long coarse wool gives protection from rain and cold. The Hampshire (Fig. 8) is a rapid-growing type with good mutton form, suited to intensive management on the arable lands of the Downs of southern 'England, where cereal production is an important part of the farming enterprise. Here, for many years, manuring and trea.ding by sheep vvere the chief means adopted for maintaining th.e fertility of the thin, light soils, especially on the chalk formation.

Stratification of the Sheep Industry in Great Britain The farmers of Great Britain are probably more aware of the importance of adaptable livestock than any other group in the world. This has been reflected in the development of their sheep industry. Mountain and arable sheep farming constitute the two major basal phases of the sheep industry in Great Britain. The former provides the majority of the ewes, the la.tter is now mainly restricted to flocks kept for breeding rams. Temporary flocks for the production of fat lambs predominate on grass in the lowlands. For these temporary flocks, ewes of mountain origin or descent are favored because of their thriftiness and good milkingqualities. Rams are

41 Figure 7. Blackfaced Highland sheep of Scotland, and a view of rugged country around Loch Ericht, typical of that upon which they graze. Photo by Robert M. Adam of the Ro yal Botanic Garden, Edinburgh, Scotland.

15 Figure 8. Hampshire Down sheep. Sheep of this type are well adapted to the relatively comfortable conditions on grain farms of southern England. Artificial shelter is provided and forage crops are grown so that an abundant supply of feed is always available. Photo fron2 The Farmer and Stock-Breeder of Dorset House, Stamford Street, London. chosen from the rapidly maturing lowland breeds. Very often a double cross is used; for example, a Hampshire or Suffolk ram may be used on Border Leicester X Cheviot ewes. These 'phases of the industry are discussed in detail by White (1932, 1939, 1944), Dinsdale (1944), Bywater (1944), Thomas (1944), and Seward (1945), and in the reports of Committees on Hill Sheep Farming in Scotland (1944) and in England and Wales (1944). Only a brief sumrnary can be presented here. Mountain sheep farming inits present form developed very largely after 1750. By the end of the nineteenth century, sheep had almost entirely taken the place of other kinds of stock on mountain land.,Hill and mountain sheep now outnumber all other typeshardy creatures well adapted to austere conditions in the districts where they are raised. The hill farmer is able, with animals of this type, to produce good-quality mutton. Wool is also an important source of income, though most of the hill breeds bear a coarse quality wool that is mostly used for carpet manufacture and similar purposes. In

16 addition to the intrinsic ability of mountain breeds to withstand the hardships of their environment, much value is placed by shepherds on the acclimatization of a flock to its district. Flocks come to know the extensive area over which they must graze, and even its unfenced boundaries. Various arrangements are made to ensure that flocks of mountain sheep remain attached to their own grazings, notwithstanding changes in tenancy or ownership. The Blackfaced Highland, Welsh Mountain, and Cheviot breeds are most important numerically among the mountain or moorland breeds. Others include the Dartmoor, Derbyshire Gritstone, Exmoor Horn, Herdwick, Lime- stone, Lonk, Penistone, Radnor, Rough Fell, Shetland, Soay, and Swaledale breeds. White (1939) has discussed the characters upon which hardiness in Welsh Mountain sheep depends, but the same characters are probably important in all such sheep. Most practical sheepmen in the mountainous areas agree that a good coat is essential. Practically no research has been done to determine the relative merits of various types of fleeces in giving protection from wind and rain. Itis generally agreed, however, that the fleece of the adult sheep should be dense, to keep out wind, and of rather coarse wool so that it sheds rain rather than absorbs it. In some cases, there are resemblances to the fleeces of primitive breeds, which include lorig hairy fibers to throw off rain, and an inner coat of v.ery fine wool. The covering of the lamb is of even greater importance, affording protection during the critical early weeks of itslife. The desirable lamb coat is thick and hairy over the whole body, and the hairy fibers are shed and replaced by wool during the first summer. The view is rather commonly held that there is a connection betweenhardiness and the presence of kemp in the fleece. White (1931) expresses the viewthat, if Welsh sheep are picked haphazard, a kempy sheep is more likely toproduce a well-covered lamb than is one with a kemp-free fleece. He holds that itis possible to select sheep whose lambs will be fully protected by a thick hairy coat and that this will, in time, give way to a fleecealmost free from kemp. The possibility of selecting sheep that have a hairy outer coat, which is shed during the first year, is also indicated in a study of hairy lambs by Pohle, Keller, and Hazel (1945). In their study, the yearling fleeces of hairy lambs were compared to those of a much larger group, mostof which were classified as non-hairy at docking time. No importantdifferences were found in the yearling fleeces of hairy and non.-hairy lambs as regards hairiness, mean diameter, variability in diameter, or medullation. This study was made on Rambouillet, Corriedale, Columbia, and Targhee sheep. Grandstaff and Blunn (1944) have observed similar changes in the proportions of hairy and wool

17 fibers in fleeces of a coarser, more primitive wooled type of Navajo sheep, in which the relative amount of hair and kemp decreased rapidly betweenone and three months of age. Other characteristics considered by White (1931) to be important in mountain sheep are activity, instinct, and intelligence. Obviously sheep grazing on rough mountain slopes must be sufficiently active to scramble and climb for their food in due season from all parts of their grazing. In general, it may be said that activity depends largely on body proportions and muscular developinent, but is also affected by relative size and weight. Other things being equal, activity is reduced by increasing size and weight. As for the form necessary for maximum activity, we need only study wild sheep, which more resemble some species of deer than domesticated sheep; from the butcher's point of view they have hardly any merit at all. The farther from the wild type we go, and the more we find ability to fatten and to reach a comparatively heavy weight at an early age, the less activitywe find. Instinct and intelligence are important under bad climatic conditions, since they enable sheep to anticipate changes in weather and to seek out feed and shelter. The degree to which thisis essential depends upon the nature of the grazing and the care and skill exercised by the shepherd. Adaptation to the feed supply is considered by White (1931) to be much the most important character affecting hardiness. He points out that mountain pasturage may be deficient in different ways, each of which makes a special demand on the constitution of the sheep. The groundmay be rough and stony, or, for other reasons, the herbage may be scanty, making it necessary for the sheep to travel and climb a great deal each day to get its fill. The feed used up in supplying the energy required to move the animal about, and particularly to do much jumping or climbing, may represent the wholenet intake for the day, leaving no surplus for milk, meat, or wool production. A similar result is produced if the feed, though plentiful, isso fibrous and in- digestible that it barely supplies sufficient nutrients for maintenance. Even when the herbage is not obviously deficient, in the above ways, it may be deficient in protein or mineral constituents, or both. The stomach can only handle a certain amount of dry matter a day. Therefore, no matter how plentiful and digestible the herbage may be, if the proportion of these essential materials is too low, there is a shortage of muscle-, bone-, and tissue-building substances. The general custom of sending mountain lambs to spend their first winter on cultivated low ground not only reduces theexposure to bad weather and gives them more digestible food, but also provides them witha larger amount of the bone- and muscle-making materialsso important in the

18 early growing stage. In the absence of such means of adding to the supply, growth on deficient grazings must be slow, arid the animal most likely to survive will have a small frame and a relatively large digestive system. The emphasis on providing good feed for ewe lambs during their first winter appears to be supported by experimental evidence from Utah, one of the western range states in the United States of America, vvhere conditio.ns are rigorous, particularly on winter range. A comparison was made by Esplin, Madsen, and Phillips (1940) of groups of ewe lambs maintained on open range and in feedlots during their first winter. All the lambs in feedlots received alfalfa hay and a mineral supplement, and in addition two groups received barley and corn silage, respectively. These trials were repeated in three consecutive years. Lot-fed lambs grew faster, had longer-staple fleeces, and 'death losses were lower. The differences in lamb production between the lot- and range-fed groups at two years of age were rather striking. Following the winter-feeding period, the lot-fed lambs were returned to the range herd, in which the controls were maintained. By breeding time the following .fall, they had lost most of the weight advantage gained over the range-fed lambs during the winter. However, the conception rate was higher than fu the range- fed ewes. Of 207 lot-fed ewes in the herd at breeding time, 64.7 percent lambed at about two years of age, compared with 45.5 percent of 123 ewes in the range-fed groups. These are average percentages based on three years' work. The difference is highly significant. Many workers, including Marshall (1908), Marshall and Potts (1924), Nichols (1926), and Clark (1934), have reported increases in lamb crop or in ovulation rate as a result of providing a high level of nutrition just before and during the breeding season. The results reported by Esplin, Madsen, and Phil- lips (1940) are in a, different category, since the special feeding ended approximately six rnonths before the first breeding season, and the advantage gained by feeding, as measured by body weight, had nearly disappeared at breeding time. Thus, it appears that the lot-feeding 6f ewe lambs stimulated development of the reproductive tract, or development of some other kind associated with reproduction, that carried over to the subsequent breeding season. This work was followed by a study (Phillips and associates, 1945) of the effects of special feed given to ewe lambs during their first winter upon the actual development of the reproductive tract. Control lambs were grazed on open range during the winter. It wasfound that the reproductive tract developed more fully in ewe lambs that received special feed. Theseresults, coupled wifh earlier work in which larger lamb crops were produced at two years of age as a result oflot-feeding during the first winter, indicate the

19 desirability of giving special attention to the feeding of ewe lambs in range flocks. Owing to climatic conditions and the special types of vegetation found in the mountains, the distribution of food supply through the year may be very different from that on cultivated low ground. At best, the growing season on upland grazing is short; it may provide a superabundance of food for a few weeks. The "hardiest" sheep under these conditionsisthe one that adjusts its size and growth to the long periods of minimum food supply. The management of a flock on arable land is quite different. It is a complex enterprise, involving an intimate association between crops and livestock. Before the introduction of root and forage crops, sheep in the lowlands were kept primarily on grass. Such folding as was practiced was quite different from that now current. In the old village system, which persisted in England throughout the Middle Ages and to the end of the eighteenth century, arable land was usually cultivated on a primitive rotation of two grain crops followed by a fallow. The village flock vvas grazed on the wastes and commons during the day, and at night was brought back to be folded on the fallows and stubbles (or, in some cases, shut up in houses or sheds). The flocks thus provided the means of enriching the arable land at the expense of the commons and wastes, which often lay at some distance from the village. The system was general in all arable districts up to the time of the great enclosures in the eighteenth century. Walking the sheep long distances every day, and the discomfort and semistarvation they often experienced on the fallows, made specialized mutton production impossible. When the fallow was replaced by root and forage crops, it was natural that a system should be devised under which the sheep consumed the crops where they grew. Gradually there developed a system of intensive sheep management, with the flocks closely folded on arable land throughout the whole year, consum- ing crops specially grown for them. For such a system the.Down breeds of sheep are particularly suitable. The Dorset Horn in its own county, the Leicester on the Yorkshire Wolds, and the Lincoln on the light arable land in its own county are other examples of arable sheep, though the system of management in the North was never so intensive as that in the South. Flocks on arable land are declining, partly because of the large amount of labor required by the shepherd and the amqunt of exposure he had to undergo during bad weather. The chief reasons, however, have been economic. Any system of livestock husbandry subsidized out of the profits from the production of grain cannot continue to exist when grain prices fall belowa certain price level. A century ago arable sheep were not in competition withany other

20 class ot livestock, but during the last fifty years there has been a rapid expansion in the dairy-cow population on mixed farms of the southern uplands in Great Britain where sheep were once supreme. Breeds developed under the arable-farming system include the Southdown, Hampshire, Dorset Down, Dorset Horn, Oxford, Shropshire, and Suffolk. In addition, sheep of the Longwool breeds such as the Cotswold, Lincoln, and Leicester usually spend part of the year on arable land. The high degree of mutton development and the rapid growth found in some of these breeds could not have been accomplished without the abundant and readily accessible feed available to the animals under these conditions. The raising of sheep on grass is also an important method of production in some parts of Great Britain outside the mountain areas. Much grass was plowed up during World War II which will no doubt be restored. There has also been a general decline in soil fertility under the heavy cropping practiced during the war. Bywater (1944) points out that one of the best ways to restore fertilityis to establish leys or pastures to be utilized by livestock, and the adoption of a system of alternate husbandry: crops, grass and clover leys to be used by stock, and crops again. The essential characteristics of a profitable flock of sheep on lowland grass include thriftiness,prolificacy, and good milking qualities in the ewes; thick flesh, early maturity, and high carcass quality. Bywater (1944) summarizes the results of a long series of experiments carried out by the staff of the University of Leeds, from 1898 to 1943, that shed some light on the suitability of various sheep breeds and crosses to, this type of husbandry: One of the basic questions to be answered under this system of sheep production is whether the Down and Longwool breeds, with their excellent mutton form, are sufficiently thrifty, prolific,and possessed of enough milking capacity to compete with ewes carrying some hill-breed blood. Practical sheep farmers have generally preferred flying or temporary bands of crossbred ewes such as Border Leicester XCheviot, or Wensleydale X Swaledale. Evidence obtained in the trials reported by Bywater(1944) supports this view. In one trial, Lincoln ewes and crossbred Border Leicester XCheviot ewes were mated to rams of seven muttonbreeds during 20 seasons, the two types of ewes being treated asnearly alike as possible. The results are summarized in Table 1. The superiority of the crossbred ewes from theborder country between England and Scotland overthe Lincoln was brought out clearly by these results. It was also reflected in the profit, which was greater by 10s. 6d. per annum per ewe put with the ram.

21 TABLE 1,RESULTS OF MATING BORDER LEICESTER X CHEVIOT AND LINCOLN EWES TO MUTTON RAMS (LINCOLN, OXFORD, SUF- FOLK,HAMPSHIRE,SHROPSHIRE, WENSLEYDALE, LEICESTER) DURING 20 SEASONS 1 Average Total live No. of No. of live weight of lambs lambs weight oflambs per No. of born perreared perlambs when ewe put Breeding ewes put ewe put ewe put wearied with rams of ewe with ramswith ramswith rams (Kg.) (Kg.) Border Leicester X Cheviot 704 1.66 1.45 40.1 58.3 Lincoln 682 1.36 1.02 40.9 41.6 1 The metric system is used throughout this and other FAO publications. For the con- venience of the reader, a table of Conversion factors is printed on page1.

A comparison was also made between Border Leicester X Cheviot and purebred Suffolk ewes, both types being mated to Suffolk rams. The best of the purebred Suffolk lambs were selected and retained for breeding, hence no direct comparison could be made of the pounds of lamb sold. However, the bigger crop of lambs produced by the crossbred ewes, combined with their superior milking qualities, made them the more profitable type. The data are summarized in Table 2. The results presented in Tables 1 and 2, although admittedly fragmentary, taken in conjunction with the experience of farmers, appear to justify the conclusion that while some Down and Longwool breeds are more suitable for stocking lowland grass than others, they are not as productive on the whole as crossbred el,ves such as Border Leicester X Cheviot, Wensleydale X Swaledale, and Border Leicester X Blackfaced Highland, all of which are produced by mating Longwool rams to mountain or moorland ewes. The rnountain ewes are not themselves so vvell suited to lowland grass conditions. This is illustrated by data obtained on Border Leicester X Cheviot and Cheviot ewes mated to Suffolk rams. The data are summarized in Table 3. Experience with Cheviot and other hill ewes straight from their native grazings has shown, according to Bywater (1944), that they tend to lamb

TABLE 2.RESULTS OF MATING BORDER LEICESTER X CHEVIOT AND SUF- FOLK EWES TO SUFFOLK RAMS DURING 5 SEASONS. No. of No. of lambs No. of lambs born reared per ewes put per ewe put ewe put Breeding of ewes with rams with rams with rams Border Leicester X Cheviot 199 1.97 1.69 S u 303 1.61 1.45

22 TABLE 3.RESULTS OF NI A TI NT G BORDERLEICESTER X CHEVIOT AND CHEVIOT EWES TO SUFFOLK RAM S DURING 4 SEASONS. Total live No. of weight No, of lambs of lambs rearedAv. li VeAv. ave lambs No. of born per weiL ; of per ewe eWeS per ewe ewe of la.mbs put Breeding: put put put when with of with with with sold rams ewes rams rams :ra S (Kg.) (days) (Kg.) Border Leicester X Cheviot 100 1.97 1.73 37.7 106 65.0 Cheviot 99 1.63 1.44 33.8 126 48.6 late in the spring and that, though potentially prolific, they require some time to become adapted te their new and more favorable environment so full fertility may be realized..An example of the increase in fertility under lowland conditions is shown in Table 4. A further comparison was made in these Yorkshire sheep-breeding experiments (Bywater, 1944) of the relative merits of four types of crossbred ewes when mated to Hampshire rarns. The ewes compared were Border Leicester X Cheviot, Suffolk X Swaledale, Wensley- dale X Swaledale, and Border Leicester X Swaledale, and they ranked in that order, in terms of total live weight of lambs produced per ewe put with rams. The data summarized in Table 5 co.nfirm the value for breeding purposes of these first-cross ewes, but indicate the need, in selecting sires to produce these firstcrosses, of paying clue attentiontofertility and early maturity as well as to size and fleece character. For this purpose, Border Leicester and Wensleydale rams are satisfactory; the Suffolk, though first class in other respects, left too many black-wooled lambs when mated to Swaledale ewes. There are certain breeds, classified with the shortwooled breeds, that are usually kept in arcas intermediate between the lowlands and the mountains or moors. Two such breeds, the Clun :3.nd. Kerry Hill, were given limited trialsin the work summarized by Bywater (1944). in one year Border

TABLE 4.RESULTS OF MATING CHEVIOT EWES TO SUFFOLK, SOUTH- DOWN, SHROPSHIRE, AND RY PT I?/ MS DURING THEIR FIRST AND SECOND YEARS ON LOWLT,:; GRA11,TG. Av. No. lambs Age born per ewe Time of ewe put with rams First year on lowland grass 5 1.20 Second year on lowlami grass 6 1.58

23 TABLE 5.RESULTS OF MATING FOUR TYPES OF CROSSBRED EWES TO HAMP- SHIRE RAMS DURING 5 SEASONS. No. of Total live No. of lambs Av. live Av. ageweight of lambs reared weight of lambslambs per Breeding No. of ewes born perper eweof lambs when ewe put of put withewe putput with when sold with rams ewes rams with ramsrams sold (Kg.)(days) (Kg.) Border Leicester X Cheviot 99 1.98 1.67 36.8 109.3 61.5 Suffolk X Swaledale 179 1.75 1.63 36.8 112.5 59.9 Wensleydale X Swaledale 172 1.81 1.58 37.1 114.1 58.5 Border Leicester X Swaledale 135 1.73 1.47 37.0 112.5 54.6

Leicester X Cheviot and Kerry Hill ewes were compared, in matings with Suffolk and Hampshire rams. The Border Leicester X Cheviot ewes were superior in fertility and in total live weight of lambs sold per ewe put with rams, as shown in Table 6, but it would be unwise to base any final judgment on one year's work. No experimental comparisons were made in which Clun ewes were involved, but data were obtained on a flock during one year which indicate that this breed may be quite usehilon lowland grasslands. The data are summarized in Table 7. In addition to the work on the adaptability of various types ofewes to lowland grasslands, Bywater (1944) summarizessome work done to compare rams of different breeds. In one experiment, Suffolk and Lincoln rams gave good results when mated to Border Leicester X Cheviotewes to produce

TABLE 6.RESULTS OF MATING BORDER LEICESTER X CHEVIOT AND KERRY HILL EWES TO SUFFOLK AND HAMPSHIRE RAMS. Total live No. of No. of weight lambs lambs Av. live of lambs born rearedweight ofAv. age per ewe No. of per eweper ewe lambs of lambs put Breedingewes put put put when when with of with with with sold sold rams ewes rams rams rams (Kg.) (days) (Kg.) Border Leicester X Cheviot 66 1.66 1.56 36.5 172.4 56.9 Kerry Hill 74 1.40 1.37 36.7 178.6 50.3

24 lambs for fattening on roots, while Oxford and Hampshirerams were not quite so satisfactory and Shropshirerams gave still poorer results. In another experiment extending over a four-year period, Ryeland, Shropshire, Southdown, and Suffolk rams were mated to Cheviotewes and the offspring of the Suffolk rams gave the greatest weight of lamb per ewe, and also the highest gross return per ewe. The Southdowns ranked second, with the Shropshire and Ryeland offspring in third and fourth place. Ina third experiment extending over three years, Oxford, Suffolk, and English Leicester rams were mated to Wensleydale X Swaledaleewes, and the offspring of the three types of rams ranked in the order in which therams are listed. In still another experiment, Suffolk and Hampshirerams were mated to Border Leicester X Cheviot ewes during five seasons, and the offspring of the Suffolkrams were slightly superior to those from Hampshire rams.

TABLE 7.RESULTS OF MATING IN A FLOCK OF CLUN SHEEP, IN WHICH THE EWES LAMBED AT TWO YEARS OF AGE. Total live No. of No. of -weight of lambs lambs Av. live lambs No. of born per reared weight of per ewe Breeding ewes put ewe put per ewe lambs at 6 put with of with with put with months rams ewes rams rams rams (Kg.) (Kg.) Chin 189 1.55 1.47 38.4 56.5

One of the most important features of these crossing experiments was the relatively small difference in results from different breeds of rams as compared with different breeds and crosses of ewes. Bywater (1944) states that it was a common experience to find greater differences in results between individual rams of the same breed than between two rams of different breeds. He believes that the results justify recommending Suffolk, Oxford, and Hampshire rams for crossing purposes, but feels that satisfactory rams for crossing .can also be found in other breeds. It is not surprising that the ewe plays a much more important part in determining the success of crossbreeding than does the ram, since the offspring produced depends largely upon the fertility of the ewe, and the growth of the lamb depends very largely upon her ability to produce milk. The multiplicity of breeds of sheep is an, indication of the long history and importance of the sheep industry in Great Britain. During that long history, natural selection has helped to develop sheep adapted to very different environ-

25 rnents, ranging from bare exposed mountainsides to rich soils and sheltered conditions in the lowlands.The stock-breeder meantime has developed animals to meet varied demands and to fit the systems of farming adopted under different conditions of soil and climate. He may in.deed have developed more breeds than are necessary to meet the variations in environment. Relatively little experimental work has been done on this point, but the evidence available indicates that there are several instances in which various breeds can be used satisfactorily under the same set of environmental conditions. This point is emphasized to indicate that even though adaptability to environment is very important, breeding for a multiplicity of types should not be carried further than necessary. This is not intended as a criticism of the present number of breeds in Great Britain, but as a suggestion to countries where the livestock industry is less developed. In such countries, where personnel and facilities for livestock improvement are apt to be lirnited, it will be most efficient to concentrate efforts on the minimum number of types required to meet local conditions. There are interesting examples of special adaptability, or apparent adaptability, in British sheep that should be mentioned. The Blackfaced Highland breed is .found chiefly in areas where heather is one of the main types of vegetation. British sheepmen believe that this breed has a unique ability to utilize heather herbage. They say that many Blackfaced Highland sheep have been taken into Wales by Scottish farmers and that most of them have disappeared except where heather is found in considerable quantities. Another example of special adaptability cited by British sheepmen is the Cheviot. The native home of the Cheviot is on land underlain by old red sandstone. It is claimed that when these animals are taken to other areas they are not long maintained, except in sections of southern Wales, northern Scotland, and Devon, where the land is underlain by the same old red sandstone. These beliefs have not been submitted to careful experimental test; when they are, the results should be interesting. The belief involving Cheviots and red sand- ston.e inay arise out of the higher productivity of grazings on this formation as compared with grazings on other soils, for examplethose derived from granite. The Cheviot, lacking the greater hardiness of the Blackfaced Highland and Welsh breeds, is yet able to survive. It is also more profitable than other breeds on the higher-class grazings on the red sandstone formation. The success of the Cheviot on red soils is probablydue to the higher productivity of pastures on the red sandstone formation and to the apparent ability of the Cheviot to utilize effectively larger amounts of good quality grass.

26 Performance of Columbia Sheep in Tvvo Environments Columbia sheep were developed by the United States Bureau of Animal Industry at the U. S. Sheep Experimental Station, Dubois, Idaho. The procedure, described in detail by Spencer and Stoehr (1941), was to cross Lincoln rams and Rambouillet ewes, and to proceed from this original cross by mating the most select first-cross rams with carefully selected first-cross ewes, and interbreeding the rams and ewes descending from them. This breed was developed under range conditions, where it has proved well adapted to production of wool and mutton. An experiment has been carried out to determine the possible adaptability of this breed to aquite different set of environmental 'conditions at Quincy, Florida. Thework was divided into two phases. In the first phase, two comparable groups ofColumbia ewes were selected. One was retained at Dubois, Idaho, and the second was placed at _Quincy, Florida, and their productivity was studied under the two setsof environmental conditions. In the second phase, Columbia rams were mated to both Columbia and native ewes that had been raised in Florida.Fi rams and ewes from the use of Columbia rams onnative ewes were interbred to produce an F2 generation. Hence,there were available for comparison, Columbia, native, Fi and F2 ewes, all of which had been raised inFlorida. The ewes and lambs of the Columbia flock at the SheepExperiment Station in Idaho were grazed on range or the sagebrush type nearDubois during the

7 aby, 4

Figure 9. Typical summer rangeof the type upon which Columbia sheep were grazed in Idaho.

27 spring and fall. While on this range, all water required by the sheep had to be hauled in tanks from headquarters to movable troughs. The forage in the spring consisted mainly of green grasses; wild onions were eaten when available and balsam furnished some feed during the early stages ofits growth. In the fall, the range grasses were field-cured and dry, and a considerable amount of the forage consumed by sheep consisted of sagebrush and bitterbrush. The cured grasses were quite low in protein and potassium. After shearing and dipping in the spring, the ewes and lambs were trailed to summer range, of which the station has two types. That on the Targhee National Forest, about 32 Km. (20 miles) north of headquarters, furnishes about three-fourths grass and one-fourth "weed" feed' and dries rapidly about the latter part of July. The other summer range is at a higher level, about 64 Km. (40 miles) northeast of headquarters on the north slope of the Continental Divide; it furnishes about three-fourths "weed" and one-fourth grass feed. Green succulent feed was available on this range until the time of killing frosts in September. After leaving the fall range (sagebrush type near Dubois) the first part of December, the breeding ewes were grazed on vvinter range about 56 Km. (35 miles) southwest in the Salmon National Forest. When the snow depths became too great for practical grazing, the ewes were moved to feedlots in the irrigated valleys where alfalfa hay was available. In the spring, for about two weeks to a month before lambing, the ewes received from 0.1 to 0.2 Kg. (1/1 to 1/2 pound) of cottonseed cake per head daily. Lambing took place in lambing sheds at or near station headquarters during April and May. The ewes received grain, usually whole oats, in addition to alfalfa hay after lambing, and until they were returned to the range. The conditions under which sheep were maintained in Idaho are partially illustrated in Figures 9 and 10. The conditions under which sheep were maintained at Quincy, Florida, were quite different. Pasture(Fig. 11) was used extensively as nutrition for the ewes and lambs, but to keep them thrifty and strong under the environment, they were fed some hay and grain,especially in times when pasture forage was relatively low in quantity and quality. Thesheep were moved from pasture to pasture rather frequently, so as to keep their forage fresh and to help in the control of internal parasites. Pastures consisted largelyof carpet grass as the prevailing forage. Wiregrass andseveral of the native grasses were often used.The temporary forages included oats, soybeans, cowpeas, The term "weedS" as used here refers to flowering plants that are of great economic value for forage on western ranges, but might be termed noxious in cultivated areas.

28 ,. ' ."; ",:;'.,.y.,,;';"-+444f;',"4;°,'

r ny, , , 41- e 1411' 414."'

'1.4

trr

'ft.%. 'S .A;:

A4'

r,1:^ aà,tyt 0,4 "^r7j1r:44 '144, t"""1:,4,%'? :;44, " ;,,e.

' tt , " ';+4;'"'",,,,, 4 41V, 4 ro,..tt,"4 4 ";474., gt 0171 Figure 10.Typical spring-fall range, predominatnly sagebush, of the type upon which Columbia sheep were grazed in Idaho.

pearl millet, and various varieties of clover. These forages were pastured in their seasons of good growth, and in the average year they furnished a major part of the feed for the sheep and lambs. Hays of different kinds fed to these sheep and lambs were made from cowpeas, and various other varieties of pea vines, soybeans, oats, and millet. The daily allowance per breeding ewe of these hays, along with other feeds, was usually about 0.9 Kg. (2 pounds), although this varied from about 0.2 to 1.4 Kg. (1/2 to 3 pounds), depending on the needs for hay as the source of nutrition and depending on its quality and palatability. Occasionally the sheep were fed about 0.9 Kg. (2 pounds) of green soybeans per head per day, with other feeds. On rare occasions they were fed about 0.2 Kg. (1/2 pound) per head daily of sorghum silage, vvith other feeds, as a succulent when pastures were sparse in lambing time. Grain was fed to the sheep and lambs when the quantity and quality of the pasture forages and hays required supplements. The daily allowance of

29 such concentrates varied from 0.1 Kg. (1pound) to 0.9 Kg. (2 pounds) per head, depending upon the need for grain. The usual allowance was about 0.5 to 0.7 Kg. (1 to 11/2 pounds) per ewe daily. The sheep were also provided with sheltering places (Fig. 12). Owing to the fact that this work was conducted in a place where temperatures are high during much of the year, an effort was made to breed ewes at such a time that lambs would be born during the cool winter months. Considerable success attended this effort, as may be seen from the following tabulation of the numbers of lambs born in each month: January 335 July 0 February 32 August 3 March 9 September April 5 October 27 May 0 November 31 June 2 December 127 The details of this work have been reported by Whitehurst, Crown, Phillips, and Spencer (1947), and a brief summary of the results is presented below. In the summer of 1933, 60 mature ewes of the Columbia breed were selected from the Bureau of Animal Industry's flock at the U. S. Sheep Experiment Station, Dubois, Idaho. The ewes were divided into two lots of 30 each, one to be retained at Dubois, and one to be sent to the North Florida Experiment Station at Quincy, (Fig. 13). Each lot was composed of 5 five-year-old ewes,

1. Typical sheep pastures of the type used for Columbia sheep in experiments at Quincy, Florida.

30 Figure 12. Shelter provided for the sheep used in experiments at Quincy, Florida.

5 four-year-olds, 10 three-year-olds, and 10 two-year-olds. The two lots were made as nearly equal as possible in wool and mutton scores and production records. Selections were made in such a manner as to obtain 30 pair mates. One ram of each of two pairs, approximately equal in individuality, production,

""' 0 '44 0, e ,

Figure 13. A group of Columbia ewes that were transferred from Dubois, Idaho, to Quincy, Florida.

31 and breeding, was retained to mate with the ewes at Dubois, and the other member of each pair was sent to Quincy. Every effort was made to eliminate all variable factors except the environmental differences existing between the northwestern range region and the southeastern pasture region. In the phase of the work in which Columbia, native, and grade sheep were compared under conditions in Florida, the Columbia sheep used were descendants of those brought from Idaho, for use in the first phase of this work. Native sheep typical of those found in the section around Quincy, Florida, were purchased (Fig. 14). The age of most of these was unknown and some were pregnant when purchased. Data were obtained on the descendants of these purchased native ewes and only those native animals of known age were included in the analysis of data. The F. ewes resulted from mating Columbia rams to native ewes, and the F ewes were producted by inter se matings, using Fi rams/ and ewes. The offspring of Columbia ewes were all sired by Columbia rams, with the exceptiofr of one lamb, whose sire was unknown. The majority of the offspring of native ewes were sired by Columbia rams, and the remaining lambs were sired by native rams. The majority of the lambs from Fi ewes were sired by Fi rams, and the remaining lambs were produced by backcrossing to Columbia rams. Only a small portion of the lambs out of F., ewes were sired by rams. The remaining lambs from these ewes were sired by Columbia rams. The extensive data reported by Whitehurst, Crown, Phillips, and Spencer (1947) were expressed in terms of productivity of ewes in each age class within each breeding group. This was necessary because animals differ with age in their fertility and in their ability to produce milk and wool. The detailed figures according to age groups were also expressed in terms of the average yearly production of a typical ewe. These figures are presented in Table .8, and are simple averages of the production of all age groups within each type of breeding. They are intended to show the production per ewe per year that would be exPected for the ages included, which were as follows: Weight and length of fleece-1 to 7 years; lambs born per ewe-2 to 7 years (based on average number of lambs born per pregnant ewe and average percent of ewes lambing from 2 to 7 years, exc'ept in the first phase where percent of ewes lambing from 3 to 7 years was used. This latter age range was used to eliminate bias because these ewes lambed at Dubois as two-year-olds and there was a marked drop in lambing percentage in the group moved to Quincy); average weaning weight-2 to 7 years. In cases where no data were available on 7- or 6-year-old ewes, the remaining data were used.

32 TABLE 8. GROSS COMPARISON OF THE PRODUCTIVITY OF THE VARIOUSGROUPS STUDIED AT DUBOIS, IDAHO, AND QUINCY, FLORIDA, IN TERMS OF WOOL AND LAMB PRODUCTION.1 Average yearly production per ewe of-

Staple length of Weaning Group Grease wool wool Lambs born weight (Kg.) (centimeters) (no. per ewe) (Kg.)

Columbia-Dubois 5.25 8.66 1.15 37.1 Columbia-Quincy 5.45 8.55 .77 30.1

Columbia 5.42 7.96 .68 31.6 Native 2.34 6.91 .99 29.9 Ft 3.95 7.92 1.30 34.5 F, 3.50 8.05 1.07 36.6 Data in the upper portion of the table are from the first phase of the experiment and those in the lower portion are from the second phase. A comparison of this type is admittedly rough, but it does place the results of a complex experiment in a form where they can beseen quickly and clearly.

Figure 14. A group of the native ewes used in the experimental work at Quincy, Florida.

33 The summary of the first phase of the experiment shows that the wool production (grease weight and length) was practically equal in Columbia ewes maintained at Dubois, Idaho and Quincy Florida, but the ewes at Dubois reproduced at a higher rate and their lambs weighed about 6.8 Kg. (15 pounds) more per head at weaning time. Columbia ewes raised at Quincy produced practically the same amount of wool, with a trifle less length of staple, as those Columbia ewes born at Dubois and either retained there or transferred to Quincy. The level of reproduction and the weaning weight of lambs of the Columbia ewes raised at Quincy were approximately the same as in those Columbia ewes that had been transferred from Dubois. Thus, even though Columbia ewes were raised from birth at Quincy, they were unable to adapt themselves to the environmental influence that limited their ability to reproduce at a high level. Columbia ewes raised at Quincy, Florida, greatly excelled the native ewes in grease weight of fleece and their length of staple was somewhat greater. However, they did not reproduce as well as the native ewes, and their lambs were only slightly larger at weaning. The majority of lambs from native ewes were sired by Columbia rams, which probably gives the native ewes an undue advantage in this comparison. Fi and F2 ewes produced fleeces that were intermediate in weight to the Columbia and na tive fleeces, and that were comparable to the Columbia fleeces in length of staple. They exceeded both parent types in average number of lambs born per ewe and in average weaning weight per lamb. The above findings indicate that Columbia sheep are not sufficiently well adapted to conditions in North Florida to reproduce at their maximum efficiency. Their advantage in fleece yield over nativeewes was offset by the lower reproduction rate. The actual economic advantage inany one year would be determined largely by the relative prices of wool and lambs. The relative effects of various environmental influences, suchas parasite infestation and fligh summer temperatures,are not known. If the poor showing of the Columbias, in terms of percent ofewes lambing, was due largely to lower resistance to parasites, then itmay be possible to overcome this handicap through the use of improved therapeuticagents, such as phenothiazine. The results indicate that, under conditions comparableto those of this experiment, Columbia rams may be usedvery effectively for crossing with native ewes. Ewes from this crosswere intermediate to Columbia and native ewes in weight of fleece, and their performance as measured by lambs produced and weight of lambs at weaningwas superior to either of the parent types.

34 Reactions of Various Breeds of Sheep to High Temperatures A study has been carried out by Miller and Monge (1946) to determine the effects of high summer temperatures in Texas upon the body temperatures and respiration rates of sheep. Comparisons were made of purebred groups of Southdown, Hampshire, Merino, and Rambouillet sheep, and studies were also carried out of crossbred groups, including Southdown X Rambouillet, Dorset X Rambouillet, and Suffolk X Rambouillet. Observations were made during the summers of 1943 and 1944. Determinations were made at different hours of the day, ranging from 8 A.M. to 5 P.M. on each ewe, and the average values for each breed group were used for comparisons. Barn temperatures ranged from 78° to 95.7° F. at the time observations were made during 1943, and from 78° to 100° F. in 1944. VVith few exceptions, the Southdown group showed the highest body temperature and respiration rate at all hours of the day, and the Hampshire group ranked second in these respects. Rambouillet and Merino animals had very similar body temperatures and respiration rates, which are somewhat lower than those of the Southdown and Hampshire groups. The crossbred groups had lower respiration rates than did the purebred animals, and their body temperatures were comparable to those of the Rambouillet and Merino groups. In general, atmospheric changes influenced body temperatures and respiration rates more in the pure-bred than in the crossbred groups. The Suffolk Rambouillet crossbreds maintained the lowest respiration rate of all groups at all times, and were least affected by atmospheric changes. They also maintained a relatively low body temperature, which fluctuated very little with atmospheric changes. Merinos exhibited the lowest body temperature atad respiration rate, and also the least daily fluctuation, among the purebred groups. These studies demonstrated the existence of definite variations among sheep of different types in their reactions to hot climates, and it seems probable that such variations may be of considerable importance in determining adaptability of sheep to such conditions. Miller and Monge (1946) point out that breeding, growth, and health records of the various groups studied were in close agreement with the efficiency of the various groups in the maintenance of low temperature and respiration rates during the summer months. They point out that further investigations on a more extensive scale are necessary before generalizations can be made, but they believe that the relationship between heat-regulating efficiency and efficient productionis more than coincidental.

35 Observations on Adaptability of Sheep in China Observations have been made on the adaptability of native and imported sheep in China which shed some light on the feasibility of introducing better stock for improvement purposes under conditions in the farming regions of North China and the extensive grazing regions north and west of this farming area. Ross (1936) visited Manchuria and adjacent areas in 1936 and observed the results of several attempts to use improved breeds for grading-up the native sheep. Some of his observations are summarized briefly below. A considerable amount of work was done at the Kunchuling station, maintained by the South Manchuria Railway Company, near Hsinking in Kirin Province. This station was not in a pastoral area so the results cannot be taken to indicate performance of improved sheep in the native sheep- raising areas. First-generation sheep from the use of Rambouillet rams showed a considerable increase in wool production, but the wool still had much of the character of the native wool, being fluffy and lacking density while still being mixed with a considerable portion 'of the coarse fibers typical of native sheep. The amount of wool was about double that of the native, or about 1.8 to 2.3 Kg. (4 to 5 pounds). The second-generation sheep (3/4 Rambouillet) approached Merino wool type, but the staple was somewhat longer and the density was less, and there was little wool on the neck, legs, and belly. There was little evidence of native-type wool fibers or hair. These sheep were housed and well bedded and were fed what was described as a generous ration, but the condition of the sheep and of the wool suggested undernutrition. Corriedales and first-generation grades of Corriedale and Mongolian sheep at this station were described as small and undersized, and as having wool that lacked density and character. Work conducted at the Darahan station in South Hsingan gave a better indication of the ability of improved types to survive under native c.onditions, since this station was in the border country between farming and pastoral regions. First, second, and "inbred cross" Merino-Mongolian sheepwere all available at this station. They were housed at night for protection against wolves and bandits but otherwise were handled under natural grazingcon- ditions as far as possible. Purebred Merinos appeared to show the effects of the' severe winter and unsuitable pasture conditions in thesummer. The staple was very short and rather oily and contained much dirt, yielding only 30 percent after scouring. The sheep were in poor condition andrams yielded only 3.6 to 4.1 Kg. (8 to 9 pounds), rarely 4.5 Kg. (10 pounds), andewes

36 2.7 to 3.2 Kg. (6 to 7 pounds). First- and second-cross sheep showed the expected increase in wool yield, but a marked decrease in clean scoured yields, from 70 percent in the native to 60 and 40 in the first and second crosses.First-cross animals appearedtobe inbetter condition than the Merinos or the second-cross animals. All the improved animalswere fed a staple ration of soybean straw, supplemented withsome lucerne hay and grain (principally kaoliang) during the winter months. The director of the station stated that he did not believe crossbred sheep could survive under natural conditions during the winter, owingto less resistance than the native sheep and relatively little aptitude for scratching through thesnow to find feed. A considerable number of Merinos were imported into Shansi Province by the Governor, Yen Shi Shan, about 1919. Ross (1936) states that these were kept under controlled conditions, being hand-fed and housed, and increased up to about 2,000 in number. When an attempt was made to run them under natural conditions, with only some feeding of hay in the winter when snow was heavy, the flock deteriorated rapidly and its numbers declined with mortality. Ross also states that attempts at crossbreeding (grading up) in the hope of increasing the hardiness of the sheep are said to have failed, there being little increase in their resistance to adverse factors, while the wool was of low value and very coarse and hairy. The vvork in Shansi was apparently done with no adequate technical supervision, hence itis difficult to evaluate the results. Ross inspected a small flock in the Saratsie District of Suiyuan Which originated from these Shansi Merinos. One ram and 10 ewes had been run with some native ewes for three years. This area is about 610 m. (2,000 feet) lower than the Mongolian plateau ?rid considerably warmer. They had apparently thrived inthis region, but when moved to the plateau death losses were heavy. At the time of inspection, only one of the ewes that originally came from Shansi remained. This and others of the pure or grade Merino type had wool only 3.2 to 3.8 cm. (11/4to11/2inches) in length, although this represented six months' growth during the summer months. All wool of the Merino types was unusually fine, as would be expected under conditions of inadequate nutrition. The grade sheep had marked admixture of coarse Mongolian-type wool with much kemp and heterotypic fiber. The three-quarter Merino sheep were reported to shear 2.7 to 3.2 Kg. (6 to 7 pounds) as compared with 0.9 to 1.1 Kg. (2 to 21/2 pounds) on the native sheep, which were valued at about $1.10 and 44 cents per Kg. (50 and 20 cents per pound), respectively. Experiments in crossbreeding between the Rambouillet and certain types of sheep native to North China were conducted over a period of nine years

37 by Moyer and Tong(1944)at Minghsien College in Taiku, Shansi, to investigate the possibilities of producing finer grades of wool in China by that method, and the availableresults have been reported by Phillips, Johnson, and Moyer(1945). Aspart of the project, specific attention was also given to a study of the local types themselves. The plan of the experiments and the available results are summarized below. Four native types were selected, Taiku, Shouyang, Hanyang, and Luan. The Taiku is the type found most commonly in Shansi, as well as in Hopei, Shensi, and possibly other provinces. It resembles closely the type found in Inner Mongolia, from which it may not differ significantly. In contrast, however, its faceis usually white and the animal appears to be somewhat smaller in size. Its fat tail is relatively small and its wool covering contains a finer under coat and a coarser outer coat. The Shouyang is a distinct type in Shouyang district, Shansi, and to a lesser extent in surrounding districts where it often occurs mixed with the Taiku. It differs from the Taiku in having a heavier tail and shorter legs, in being somewhat lighter in weight, and in having a heavier fleece, which is somewhat wavy and lustrous. Its wool is recognized as a distinct class on the Tientsin market. The Hanyang type is found in western Honan. A similar animal, found eastward in Shantung, is believed to be of the same type, and that found around Tungchow, Shensi, seems to be similar. The Hanyang type is characterized by an unusually heavy fat tail and by a finer wool which is also somewhat crimpy. Its wool isrelatively uniform in character, without a distinct inner and outer coat. On the Tientsin market this is considered the finest of Chinese wools. Unlike the Taiku and the Shouyang, twinning is fairly common in this type. The Luan type is named for a city in southeast Shansi (now called Chang- chih), around which itis commonly found. It is distinguished by its tail, which is long like more western breeds but is enlarged around the base, resembling the tail of first-generation Rambouillet-Taiku crossbreds. In size and in the characteristics of its wool it resembles the Hanyang type. The Rambouillets used were mostly of a smooth-bodied type, obtained from the Deer Lodge Farms Company in Montana, although some lightly wrinkled rams, imported from Wyoming and Montana by the Chinese Government, were also used. The Rambouillets included both rams and ewes, and their offspring were utilized in a study of the behavior of this stock under local conditions. The first experiments, begun in1932,included only two breeds, the Taiku and the Shouyang. Between 30 and40ewes of each of these types were successfully bred, approximately one-half being withrams of the Rambouillet and

38 one-half with rams of their own native type. Later, with help from theNational Economic Council of the Chinese Government and from the Rockefeller Foundation, the experiment wasvery much enlarged. Two additional types were introduced, the Hanyang and the Luan, and the number ofewes of each type in the experiment was increasedto about 120. A part of this increase in program was accomplished in 1936 and therest was completed in 1937. The Japanese invasion, however, completely ruined the workof that year, and many sheep were lost. A portion of theprogram was reestablished in 1938 and continued into 1941. Crossbreeding and grading up, in the main part of theprogram, was not carried beyond the first and second crosses with the Rambouillets, which produced half-blood and three-quarter-blood Rambouillet animals. Itwas considered that little additional information of value would be gaincd by going further. During the last several years of the experiment, however,a large number of Rambouillet-Taiku half-bloods were backcrossedtothe Taiku in order to bring out the inheritance of certain genetic factors and in order to investigate the beginning steps in one plan which might be followed in fixing a new improved type. Experimental animals of all types were raised during any givenseason under approximately the same environmental conditions. Thesewere a little better than the conditions under which local animals are commonly raised, but not very much better. Breeding-stock gained the main part of theirsus- tenance the year round by grazing in the surrounding country, A certain amount of supplementary feedstuffs was given during the poorest months for grazing, usually between January and April, consisting of materials available, such as leaves, sweet-potato vines, buckwheat straw, bean straw, and bean pods. No concentrates were fed, except to the Rambouillet stock, which was grazed with the rest but otherwise received favored treatment. All animals were quartered in the open except during the coldest months, when they were placed at night in simple unfloored sheds. Pens and yards were swept daily, thus reducing to some extent the danger from parasites. The breeding season, following local practice, began in July and usually ended in October, and the lambing season began in December. Lambs were given careful attention at birth, and following birth they were kept in pens and yards until about April, when they were pastured during the daytime. Upon weaning they were fed mainly with carrot tops, the preferred food for lambs in that region. No concentrates were fed. Weight and measurement of all offspring were taken at birth and at intervals of one month thereafter until reaching an age of 6 months. Similar records were

39 taken subsequently at 9,12, and 18 months and afterwards twice a year, following the spring and fallshearings. Measurements included length of legs, height at the shoulders, body circumference, width of loins, circumference of tail at base, and others. Weights and similar measurements were taken of the breeding-stock twice yearly, after the spring and fall shearings. Local animals were sheared according to local practice. For the Taiku and Shouyang types, this consisted of pulling out the fine undercoat with a coarse, clawlike comb in the spring. In the latter part of July or early August the animals were clipped, removing the coarse outer coat and whatever else remained or may have grown (Fig. 15). The Hanyang and Luan types and all crossbreds were sheared once annually, in the spring. Records were kept on the gross weight of fleeces and the scoured weight as estimated from a representative sample. Analysis of these data and of data on reproduction was interrupted by World War II, hence detailed results cannot be reported. Informationissufficiently complete, however, to state in a general way some of the results obtained. First-generation crossbreds of Rambouillets with the Taiku and Shouyang types were appreciably heavier than the native animals (Fig.16). With respect to meat, a local prejudice existed against the flavor of the-Merino breed, from experience gained with animals ofthatbreed introducedearlier. A difference in flavor could usually be detected also in meat of the Rambouillet crossbreds, in comparison with meat of native animals, but the objectionto it was not strong. Average wool production of the Taiku type was around 0.9 Kg. (2 pounds). That of the first-generation cross with Rambouillets was about 2.3 Kg. (5 pounds). The three-quarter-bloods averaged approximately 3.6 Kg. (8 pounds), and individual animals produced as muchas 4.5 Kg. (10 pounds).The quality of wool also was better. The fleeces of the half-bloods carrieda certain amount of a coarser outer coat, more prominent in the rams but relatively inconspicuous in the ewes. Fleeces of the three-quarter-bloods containedno coarse outer coat, and the wool throughout was finer and contained more yolk. Shouyang native animals produced 1.4 Kg. (3 pounds)of wool per head, and the crossbreds were similarto those of the Taiku except that the wool, in general, seemeda little coarser. Data available for the year 1935, from experimental offspringwhich then were 18 months or older, are shown in Table 9. It should be mentioned that wool yields for all types of animals thatyear, were, in general, lower than the average.

40 t.t,

f ' .0v0e 4

, 4V. ,

t ;A ,4:tt;4.,tti ,

*'"1

.g, , ew,/ "

a, t.4.0,

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Ve,',7

Figure 15. Results of grading up Taiku sheep with Rambouillet sheep at Minghsien College. Top, left to right: Rambouillet ram, Taiku ewe, and 1/2 Rambouillet-1/2 Taiku ewe. Of the two piles of wool in front of the Taiku ewe, the left is fine undercoat pulled in the spring and the right is coarse outercoat and a little undercoat clipped in July. Bottom: Pulling wool (undercoat) from Mongolian sheep with a coarse comb in the spring. Photos by Raymond T. Moyer.

With respect to hardiness, it was soon demonstrated that the Rambouillet breed was not as hardy as the native breeds under local environmentalcon- ditions. Stomach worms killed all the lambs born the first year, but this pest was fully controlled in subsequent years by drenching with copper

41 TABLE 9.DATA ON BODY WEIGHT AND YIELD AND QUALITY OF WOOL PRODUCED BY SHEEP OF VARIOUS TYPES IN EXPERIMENTS AT MINGHSIEN COLLEGE, SHANSI PROVINCE, CHINA. Average Average Taiyuan Type of sheep Number body wool yield, price per lb. averaged weight unscoured of wool Kg. Kg. (Chinese yuan) Taiku 14 32.4 0.72 .15 Taiku-Rambouillet half-blood 19 38.1 1.99 .38 Shouyang 12 30.0 1.26 .18 Shouyang-Rambouillet half-blood 14 39.9 2.22 .38 Rambouillet 3 57.1 5.35 .47 sulphate. Half-bloods seemed only slightly less resistant than native animals to this and other adverse factors in the environment, but three-quarter-bloods were definitely less hardy. This was shown in a great proportion of deaths before reaching maturity and in the less healthy appearance of those that survived. Experience in these studies suggests that no animal less hardy than the half-bloods would be raised successfully in that region unless the present environmental conditions were appreciably improved.

The Mongolian sheep used in this study were of the fat-tail variety. Fat- tailed and fat-rumped sheep are common in many parts of Asia and North Africa. Therefore the behavior of tail type in inheritance is of considerable importance in attempts to improve these animals with imported types. In this study, an attempt was made to investigate the inheritance of the tail characteristics. Length appeared without exception to be dominant. All first- generation crossbreds had a long tail, resembling the Rambouillet, although the comparative number of vertebrae was not determined. The curlsome- times found at the end of a fat tail seems to be inherited as a separate character', possibly as a single factor. Some long tails of the crossbreds hada slight twist at the bottom, while others were without it. Fattiness appearedto be governed by multiple factors. First-generation crossbreds hada partial fattiness, which expressed itself as an enlargement around the base. In thecase of the Rambouillet-Hanyang half-bloods, the amount of fatwas quite considerable. Three-quarter Rambouillet-one-quarter Taiku animals had littleor no enlargement of the tail (Fig. 17).

42 . ny44,.:...:. 4, '. 1 ,'...04.4.1''N','1 ",'',,,'-.',,A'',...,::..,-1..,:.':.,,4'v. 4;4-4

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40W44112Ar

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Figure 16. Results of grading up Mongolian sheep of the Taiku, Shansi, area with Rambouillet rams at Minghsien College. Top, left to ricNt:

Taiku ewe; 1/2Taiku-1/2 Rambouillet; 1/4 Taiku-3/4 Rambouillet; and Rambouillet. Middle: Group of young 1/2 Rambouillet-1/2 Taiku rams. Bottom: Group of 34 Rambouillet-1/4 Taiku ewes. Photos by Raymond T. Moyer.

43 Figure 17. A study of variation intails.Left to right: Rambouillet (docked); 3% Rambouillet% Shouyang;1/2Rambouillet-1/2 Shouyang; Hanyang; Shouyang; and 1/2 Rambouillet-1/2 Hanyang. Photo by Raymond T. Moyer.

Improving Deccan Sheep by Selection and Grading up with Merinos The Deccan breed of sheep of southern India is relatively underdeveloped for both mutton and wool production. The wool is coarse, much of itis colored, and it is used primarily in the manufacture of rough blankets. The annual yield of wool per sheep is about 0.3 Kg. (1/4lb.) on the average. Khot and Deshpande (1945) have reported on some attempts to improve these sheep. A foundation flock of white animals was selected and the preliminary examination of the fleeces showed that there was a wide variation in the quality of wool. Some sheep had more hairy fibers than others, and a few yielded a comparatively softer and woolier clip. Most fleeces contained wool and hair in a mixed state, though certain sheep had relatively little hair in their fleeces. The foundation animals were divided into three types: (1) sheep having little or no hair in the fleeces; (2) sheep with hairy fibers that grew continuously; and (3) sheep with short hairy fibers thatwere seasonally shed. The latter two types were ultimately discarded,so that only sheep of the first type were retained for further breeding. The original flock had hairiness in the fleece varying from 7 to 80percent, but by pursuing a method of rigorous selection, it was possible to establisha herd of sheep with insignificant hairiness (Fig. 18). A total of 250ewes were purchased for experimental work, but only 49 were retained. At the time of thereport by

44 Khot and Deshpande (1945), a flock of 110 white-wooled sheep had been formed from these animals and their progeny. In 1938, a small Merino flock of 20 ewes and 3 rams was imported from South Africa to the Sheep Breeding Research Station at Poona, Bombay Pro- vince, to study the conditions essential for acclimatization of this breed to the Deccan environment (Fig. 19). The purpose was also to ascertain whether a fine-wooled crossbred sheep, able to withstand the hard rural conditions of the province, could be evolved by the use of Merino rams. These imported sheep were small in size, like the local breed, but they yielded 2.7 to 4.5 Kg. (6 to 10 lbs.) of fine wool and, except for a small portion of the face and legs, their whole body was covered with dense wool without any hairiness. To begin with, considerable difficulty was experienced in the management of this breed, due to lack of knowledge about its habits and requirements., It was observed that the Merino is more excitable and has less flock instinct than the Deccan sheep. Another habit of the breed which is of importance in this environment is that the Merino sheep graze abundantly in the monsoon when the Deccan hills suddenly develop a dense growth of green grass. Unlike the Deccan sheep, which has the habit of selective grazing, the Merino nibbles at all types of herbage. After four years' experience, Khot and Desh- pande conclude that it is possible to maintain and breed these sheep in good

f33,34!,W3)3","3.3>;V3"3°3";30313.3?,ft'Pv 3 '0,3 3",..3 343,d313," 333 3.3 ° 3 " 3

Figure 18. A flock of selected Deccan sheep. Note that all the fleeces are white, although many animals with colored heads are present. Local shepherds consider the presence of black color on the face as a sign of hardiness because this character appears to be associated with hard black hooves. After Khot and Deshpande (1945).

45 condition, their requirements in management being as follows: provision of a little green fodder during the day; provision of a thatched hut for shelter from the afternoon sun; allowing three to four hours of grazing daily; providing a rackful of well-made hay to nibble at; and, disturbing the animals as little as possible. After initial experience at Poona, the small Merino flock was transferred to a substation in the Belgaum district where better facilities for green grazing were available, where the weather is cooler, and ternperatures are more equable. Some crossbreeding was done with Merino rams and Deccan ewes (Fig. 20). The first-generation animals yielded heavier and finer fleeces than the native Deccan animals, and in some cases the wool was almost as fine as that of the Merino parent. However, a great deal of variation was found, both in the color and quality of the fleeces. All the inherent colors of the

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Figure 19. A flock of Merino sheep grazing under Deccan coriditionsin Bombay Province, India. After Khot and Deshpande (1945).

46 ' Figure 20. A group of crossbred Merino X Deccan sheep. After Khot and Deshpande (1945).

Deccan sheep appeared in the progeny, though all the Deccan ewes that were mated to Merino rams had white fleeces. A few second-generation (F) animals were produced and distinct segregation of wool types was observed. The crossbred animals yielded from 1.1 to 2.3 Kg. (2.5 to 5 lbs.) of wool, and were hardier than the Merino. They couldwithstand Deccan conditions easily, given careful shepherding.

Reactions of Southclown Sheep to Two Environments Itis generally recognized that the development and performance of an animal depend upon both its genetic makeup and its environment.The relative importance of these two factors obviously varies with the conditions under which the animal is raised and maintained, and the genetic adaptability of an animal te the environment to which it is exposed. Some attention

47 has been given to the breeding of animals adapted to different environmental conditions. This is well illustrated in a practical way by the stratification of the sheep industry in Great Britain. Another illustration is the recent work on the development of beef cattle adopted to subtropical conditions through the use of a combination of European and zebu cattle blood, which will be discussed in a subsequent section. Still another example is the development of Columbia sheep (Spencer and Stoehr, 1941) from a crossbred foundation, producing an animal that could make better use than the Rambouillet of the more productive range lands. However, relatively little work has been done in this field and even less has been done on the reactions of livestock to what may appear to be rather unimportant changes in environment. The United States Bureau of Animal Industry had maintained a flock of Southdown sheep atBeltsville, Maryland, for many years (Fig. 21). These sheep received excellent care at the hands of a competent herdsman. During the summer they were kept on temporary pastures and were rotated at frequent intervals to ensure fresh feed and to keep parasite infestation at a minimum. During the winter they received good quality hay and sufficient grain to keep them in excellent condition. It became desirable, because of space requirements, to transfer this flock to the United States Morgan Fiorse Farm near Middlebury, Vermont. At Middlebury, these animals were fed as a separate flock during the winter, receiving good quality hay, corn silage, and grain. In some cases, the Southdowns received second-cutting alfalfa, while other sheep at the station received .first-cutting timothy and clover. They failed to thrive, and were transferred back to Beltsville after about twoyears. The dates of transfers and of breeding seasons wereas follows: Action Date Ewes last bred atBeltsville,beginning September 24, 1937 Flock transferred to Middlebury October 25, 1938 Ewes first bred at Middlebury, beginning November 21, 1938 Ewes last bred at Middlebury, beginning November 30, 1939 Flock transferred toBeltsville September 16, 1940 Ewes first bredatBeltsville, beginning September 17, 1940 Details of this study are presented ina paper by Phillips and Spencer (1948). The response of the animals to two environmentswas so strikingly different that earlier records were explored to determine ifany supporting or contra- dictory evidence might be obtained. Itwas found that an earlier transfer of Southdown animals had been made between thetwo stations. This transfer did not involve the whole flock, but only lambs thatwere born in 1915 and 1916 and transferred to Belstville after they had been weaned. Toget lifetime records for comparison, data were assembledon ewes born at Middlebury

48 Figure 21. A Southdown ram, illustrating the larger type used in the early breeding work at Middlebury, Vermont, and Beltsville, Maryland. After Phillips and Spencer (1948). during 1910 and 1911. These were compared with lifetime data on the ewes born in 1915 and 1916 at Middlebury and later transferred toBeltsville. Details of this study are also reported by Phillips and Spencer (1948). The average results obtained with the Southdown flock that was shifted from Beltsville to Middlebury and then back to Beltsville are shown in Table 10. The performance of the animals while at Middlebury was definitely inferior. For example, ewes of all ages weighed less while at Middlebury than did ewes of similar ages before transfer tothat station and after being returned to Beltsville. The percentage lamb crop was also generally higher at Beltsville than at Middlebury, though in two small groups (seven- and eight- year-old animals) high percentages were recorded at Middlebury. The numbers of animals involved in these cases however, are too small to give any importance to the results.

49 Figure 22. A Southdown ram, illustrating the smaller, more compact type used in the later work at Beltsville, Maryland, andMiddlebury, Vermont. After Phillips and Spencer (1948).

The ewes also appeared to produce less milk while at Middlebury, since the lambs weighed from 4.5 to 6.8 Kg. (10 to 15 lbs.) less at weaning time than lambs from ewes of similar age produced at Beltsville. The effects of the adverse environment are also shown in the fleece data: the gross weight and the length of fleece was less in ewes of all ages while at Middlebury than before their transfer to that station or after their return to Beltsville. The data obtained on Southdown sheep produced inearlieryears at Middlebury, some of which were transferredtoBeltsville as lambs, are presented by Phillips and Spencer (1948). Data obtained in those early years were not as complete as those obtained in the phase of the study already reported. Also, the comparisons are not as valid, since the whole flock was not transferred. Differences in the type of ram used or even differences in the trend of selection within the flock might have had some influence on the results obtained. It should be emphasized that the age of these data makes it impossible to get a clear picture of the environmental conditions to which the animals were subjected at the two stations during the earlier years. It seems reasonably certain, however, that the conditions for sheep production during 1915 and subsequent years at Beltsville were not so highly developed as they were

50 TABLE 10.DATA ON BODY WEIGHT, REPRODUCTION, AND PRODUCTION OF LAMBS AND WOOL OF EWES AT BELTSVILLE, MIDDLEBURY, AND BELTSVILLE DURING THE PERIOD 1936-1943. Body weight and percentage dry ewes Age Body weight " Percentage dry e-wes 2 of ewe Belts- , Middle- Belts- Belts- Middle- Belts- ville btiry ville ville bury ville (Kg.) 38.5 28.3 37.6 2 40.7 30.6 42.9 3 43.5 33.4 44.1 4.76 20.00 0.00 4 46.0 34.0 50.6 13.33 33.33 0.00 5 48.2 36.7 44.6 0.00 28.57 12.50 6 39.6 39.1 41.4 16.67 0.00 0.00 7 39.1 38.7 43.6 0.00 0.00 16.67 8 43.2 35.5 48.9 0.00 0.00 20.00

Percentage lamb crop and weight of lambs

Age Percentage lamb crop 3 Weight of la nbs of Belts- Middle- Belts- Be ts- Middle- Belts- ewe ville bury ville ville bury ville (Kg.) 1 2 105.55 ibbldo 2114 i516

3 115.00 100.00 100.00 . 26.3 14.8 22.3 4 146.15 100.00 180.00 23.3 17.9 20.2 5 126.67 100.00 114.28 24.5 18.0 22.0 6 140.00 100.00 150.00 23.8 19.2 18.8 7 100.00 150.00 120.00 25.5 18.5 21.4 8 200.00 150.00 125.00 20.0 16.5 20.2

Fleece data

Age Fleece eight, grease (Kg.) 1 Fleece length, centimeters 4 of Belts- Middle- Belts- Belts- Middle- Belts- ewe ville bury ville ville bury ville 2.70 1.94 2.49 6.73 6.00 6.84 2 2.37 1.90 2.30 5.61 4.59 5.84 3 2.05 1.76 2.26 5.22 4.18 4.83 4 2.29 1.74 2.46 5.31 3.99 5.06 5 2.09 1.72 2.17 4.66 3.88 5.15 6 2.32 1.75 2.32 4.97 4.11 5.50 7 1.82 1.46 2.15 4.32 2.75 5.37 8 1.98 1.45 1.74 4.30 3.05 4.28 I. All bod.y weights of ewes were taken on October 1 or at the nearest weigh day, with the exception of those for yearling ewes, which vvere taken on the weighing day nearest one year of age. The weights at Middlebury were taken about one yea.rafter arrival and just before transfer back to Beltsville. 2 Based on number of ewes in flock at lambing time. 3 Based on number of ewes lambing. 4 The fleece weig,hts and fleece lengths for yearlings were adjusted to 365days' growth. All others represent one year's growth.

51 during the period 1936-1943. During the intervening period, much attention had been given to the development of temporary pastures and rotation systems for their use, and also to the control of internal parasites. The available data, although inadequate in many respects, indicate little difference in the performance of the Southdown sheep at the two stations during this phase of the work. The only marked difference is in body weight, and in this case it is the reverse of the other results, the sheep being heavier generally at Middle- bury than at Beltsville. The animals used in the earlier work were of a larger, more rugged type than those used in the studies conducted in later years (Fig. 22). It is quite possible, therefore, that they may have been better adapted to the environmental conditions at Middlebury. In comparing actual weights of the animals, it is necessary to omit the yearling weights, since none was available from the early data. Using data for animals ranging from two to eight years, and average figures from the two stations, it is found that in the early years, the various age groups ranged from 46.2 to 68.6 Kg. (101.7 to 151.0 lbs.), while in the later work the range was from 30.6 to 50.6 Kg. (67.4 to 111.4 lbs.). Weight averages for all age groups, exclusive of yearlings for animals in the early and later work were 56.4 and 41.1 Kg. (124.0 and 90.5 lbs.), respectively. This marked difference in size illustrates a trend in selection towarda smaller, more con-ipact type, and this change in size and form may have resulted in a lessened ability to thrive on pastures and roughage, NAThere themanage- ment system left no place for pampering the animals.

Experience with the Introduction of Sheep in Iceland Sheep have been maintained in Iceland for approximately1,000 years as multiple-purpose animals for the production of milk, meat, skins, and wool. Milk production was the most important function, andany attempts by farmers to improve the animals undoubtedlygave first consideration to this point. However, there was a fundamental change in sheep-farming meihods, beginning about 1910. Farmers beganto put more emphasis on the production of lambs and wool. The native sheepwere not ideal in conformation for the production of high quality lambs, but theewes were good milkers and the level of fertility was high. These native sheep (Figs. 23 and 24)are representative of the short-tailed breeds of northern Europe, andare similar in many ways to the native sheep of Norway, Sweden, Finland, andNorth Russia, but somewhat heavier and generallymore robust. Mature rams weigh about 85 kilos on theaverage, and mature ewes approximately 50 kilos.

52 a"kr,

,"",,3:,`, "", kkk3k3,"4:".,,),

tp;t2

,,,..,..,44:?,...

a' k ,

J4,),

34 kt"."9

k a

"."

" .

1 "kak (a"kakkk

Figure 23. Atypical Iceland ram, aged four years.

Photos provided by Huidor Poisson, Minis-try of Agriculture, Reykjavik, Icelancl

Figure 24. A typical mature Iceland ewe.

" "

Figure 25. Asix-year-old ram of the Kleifa strain of sheep in Iceland.

Photos provided by Haldor Poisson, Ministry of Agriculture, Reykjavik, Iceland

Figure 26. Border Leicester sheep imported into Iceland and used in crossbreeding experiments.

54 The conditions under which they are maintainedare generally well suited for sheep production. The climate is cool and fairly mild, with sufficient rain and no long spells of drought. There are extensive natural grazing areas, some of which produce abundant growths ofgrasses, sedges, and some shrubs. The mountain areas do not provide much grazing butcan be used for summer pasture. A number of importations of sheep for breedingwere made before 1900, but only one of these has left any impressionon the sheep population. In one district there is now a strain of sheep known as the Kleifa (Fig. 25), which has different characteristics than other Icelandic sheep. Theyare rounder of body, have a slightly longer tail, the fleece ismore dense, and the wool is somewhat closer. These animals are less fertile but have somewhat better mutton form than the other sheep in Iceland. They are supposed to be descendants of sheep imported from Scotland and crossed with the native animals. It appears likely that the imported sheepwere either Cheviots or Border Leicester X Cheviot. Difficulty was encountered in the early importations of sheep because of the introduction of diseases. For example, about the middle of the 18th century some Spanish sheep infected with scab were imported. Control measures were not known at that time, so the disease was finally eradicated by slaughter- ing all animals in the infected areas. Scab was again introduced with sheep about the middle of the 19th century. Results were more disastrous than in the earlier epidemic. The disease vvas brought under control only after informa. tion became available on control of scab by dipping. Early in the present century interest again developed in the importation of improved breeds of sheep from Great Britain and elsewhere for use in grading up the native animals. There was great resistance to thisidea because of the disastrous experiences of earlier importations, but laws were passed in 1931 enabling the government to make importations for breeding purposes. In that year a stnall group of Border Leicester sheep was imported from Scotland (Fig. 26). The rams were used to produce first-cross animals for slaughter only until 1940, when first-cross animals were kept for breeding. No planned experiments were carried out with these animals, but several farmers gave their observations: The hybrid lambs were strong and vigorous at birth and had a dense birth-coat, enabling them to withstand cold and wet weather. They grew rapidly and produced carcasses that were heavier and of somewhat better quality than native lambs, provided the ewes were kept under better-than-average conditions of winter feeding and summer grazing. When kept under less-than-average conditions the crossbred lambs yielded

55 carcasses of lighter weight and somewhat poorer quality than the native Iambs. In 1941 it was decided to test Border Leicester X native first-crosses for breeding and back-crossing. A few farmers were given permission to keep first-cross females for breeding, and some experiments were undertaken at in agricultural school farm in Hvanneyri. In ,this work purebred Border Leicester and native animals were produced, Border Leicester X native rams and ewes were interbred, and Border Leicester rams were mated to native ewes. The results are summarized in Table 11.

Another experience withintroduceddiseasesoccurredin1933, when twenty Karakul sheep were imported from the University of Halle in Germany for the production of fur. The animals appeared on inspection to be healthy, and after three months quarantine were brought into contact with native sheep on farms in several districts. In the course of one to threeyears, serious diseases previously unknown in Iceland broke out in several native flocks that had been in contact with the imported animals. Two of these diseases affected the lungs. After much research it was concluded that one of these was a disease known in South Africa under the namejaagziekte,which may be described as epizootic antenomatosis. This disease was very contagious, and in the course of three years had spread over half the country. Itwas stopped only by quarantine fences betvveen infected and healthyareas. Native sheep were highly susceptible, and up to 70 percent of the animals in some flocks took the disease and died in the course of a few months. Some flocks appeared to have greater immunity than others, and the death rate has been declining.

TABLE H SUMMARY OF PRODUCTIVITY OF VARIOUS TYPES OF SHEEP IN ICELAND

AverageAverage Percent- live- live- Average AverageAverage age weight weightweight Breeding Breeding number liveweight of lambs of of year- of fleece of ewes of ramsof ewes of ewes inreared lambs in ling in Oct., kilos as twins Oct., ewes ingrease, kilos Oet.,kiloskilos Border Border Leicester Leicester 20 65.1 22.9 33.4 52.1 3.6 Border Border Leicester Leicester X Iceland X Iceland 28 57.7 42.1 36.6 52.5 3.4 IcelandBorder Leicester 18 55.9 42.8 41.1 2.3 Ice.land IMand 15 55.9 43.4 37.2 52.3 2.3

56 The other disease affecting the lungsisa progressive pneumonia, and appears to be the same as that known in the United States as "lunger disease." While contagious, it did not spreadas rapidly asjaagziekte,but has now spread over approximately the same area. During the past 10 years, Palsson (1947) has had under investigation 47 flocks infected with thetwo diseases, to determine the extent of losses and the age at whichmost sheep were lost. The percentage of animals of each age that were lost in these flocks because of the two diseases is given below:

Year Percentage 1st none 2n d 4.6 3rd 13.5 4th 16.5 5th 13.1 6th 9.2 7th 8.7 8th 5.0 9th 4.0

Losses from other causes, including culling of animals unfit for breeding, amounted to about 20 percent, hence only between 5 and 6 percent of the ewes reached the average age of nine years without being affected with one of the two diseases. In a flock of healthy native ewes, the average culling age is nine years. Of 47 flocks studied, nine in which the losses have been lower during the last seven years showed an average annual loss 15 percent less than in twenty flocks N,vhere losses were greatest. This is an indication that flocks may vary in their degree of immunity. The high susceptibility of native sheep to these diseases, combined with the fact that the diseases cause only niinor losses in other countries, indicated that imported sheep might be better able to resist them. A study was therefore made in which Border Leicester X native lambs were kept for breeding in areas infected with the disease. Results recorded by Palsson (1947), summarized in Table 12, indicate that the hybrid animals have greater immunity than native sheep.

TABLE 12.SUMMARY OF LOSSES IN ICELAND AND IN BORDER LEICESTER X ICELAND NATIVESHEEP FROM L UNGER AND JAAGZIEKTE DISEASES. Breeding of Animals Up to 2 yrs. Up to 3 yrs. Up to 4 yrs. Up to 5 yrs. Border- (percent) Leicester X native 2.3 12.5 14.9 16.7 Iceland (purebred) 3.0 20.8 37.1 52.6

Palsson points out that since only 186 crossbred animalswere included in these observations, the resultscannot be considered as conclusive. However, they do indicate a definite difference in susceptibility.A small flock of purebred Border Leicesters, maintained at the Agricultural SchoolFarm in Hvanneyri, has been in contact with infected sheep since 1941 buthas not been affected with either of the diseases. Losses from othercauses than these two diseases, however, have been considerably greater in Border Leicester and inBorder Leicester X native sheep than in the natives. Palsson (1947) concludes from his experience with sheep and other livestock that improvement in countries having rathersevere climates and primitive types of animals can best be obtained by basing the improvement workon careful selection of native types rather than importing improved animals that have been developed in otherareas with much better climatic conditions. He feels that the disease problem is especially important inareas that have been more or less isolated, and where the native animals may have had no opportunity to develop resistance to diseases prevalent in areas from which breeding stock might be imported.

Improvement of Navajo Indian Sheep Much of the range land in the southwestern United States is semiarid and the sparse rainfall places definite limits on livestock production. The grazing land on the Navajo Indian Reservation is typical of much of the range country in the Southwest. A study of the adaptability of sheep on this reservation should yield information useful to sheepmen throughout the Southwest and in similar environments in other countries.The reservation, in northeastern Arizona and adjacent parts of New Mexico, Utah, and Colorado, contains more than sixteen million acres of land, upon which approximately 495,000 sheep are grazed, with about 50,000 goats, 25,000 horses, and 10,000 cattle. Sheep and wool are of major importance to the Navajo Indians. They weave some of the wool into rugs, and in this way are able to market both wool and labor. The remainder of the wool goes into regular wool-marketing channels. Continued use of fine-wool rams on the reservation has reduced the amount

7igure 27. Aflock of sheep on the Navajo Reservation. Animals with long, open fleeces are predominantly of old-type Navajo breeding, while those with shorter, more compact fleeces have some fine-wool blood. Photo by Milton Snotv, Navajo Service, Window Rock, Arizona.

59 of wool suitable for hand weaving, and has brought about a consequent reduction in the quantity of rugs produced. Therefore, production of a sufficient amount of high-quality weaving wool becomes of considerable importance in the economic life of the Navajo Indians. The old-type Navajo sheep are now encountered in only a few portions of the reservation which are farthest removed from white influences. These animals are clean-legged, have long, narrow bodies and are quite upStanding. They resemble the Churro and Tarhumara sheep found in parts of Mexico. Their fleeces consist of a long coarse outer coat and a short fine undercoat, with many kempy and medullated fibers which are generally characteristic of sheep with unimproved wool. The fleeces are open and contain relatively little grease. These animals are very hardy, and able to find a living under semidesert conditibris. The ewes are good mothers. The majority of the sheep now on the Navajo Reservation show the results of many crosses with improved breeds (Fig. 27), and in contrast to the old-type Navajo sheep the wool is short and relatively fine, and its grease content is greater. Many of the present animals are of rather poor grade Rambouillet breeding, though it is possible to find many individuals showing resemblance to other breeds. The quality of blankets and rugs produced by the Navajos has deteriorated rapidly since about 1915, owing to the diminishing supply of old-type Navajo wool, which is superior for handicraft purposes to the other wool produced on the reservation. A project designed to develop a type of sheep adapted to the ranges of the Southwest, and which would produce wool suitable for hand weaving, was initiated in 1935 by the U. S. Bureau of Animal Industry in co-operation with the Indian Service of the U. S. Department of the Interior. About 800 old- type Navajo ewes and 20 rams were purchased. From this stock and improved rams, four lines of breeding were eventually established. These included two lines of Navajo sheep which were being improved by selection and two lines of crossbred type, containing about 1/2 Navajo and 1/2 improved blood. In one of these latter lines theimproved blood was predominantly from the Corriedale breed, and in the other it was predominantly from the Romney breed. In the conduct of research under that project, it was necessary to initiate breeding work, and to study the type of wool best suited to hand weaving as the breeding work progressed. Consequently, it was not possible at the outset to define accurately the objectof the breeding program insofar as fleece characteristics were concerned.The important results thus far may be summarized as follows:

60 Fine wool, with short staple, close crimp, and high density and shrinkage cannot be thoroughly carded by hand. It yields lumpy, irregular yarns and rugs of inferior quality. Long-staple, light-shrinking, quarter-blood woolwas fully as easy to card and produce rugs that were equal, if not superior, in qualityto those made from the best Navajo wool. The excellence of this type of wool for hand weaving, and its desirability for commercialuses in which this type of wool is required, make it well adapted to the dual requirements of the Navajo Indians. Navajo sheep have demonstrated their superior adaptability to the range conditions of the area. This is evidenced by the reproduction and lamb production records during a nine-year period (1937-45) and a three-year period (1943-45), which are shown in Table 13. The rather consistent superiority of Navajo ewes in fertility and al3ility to raise lambs is apparently a reflection of the adaptability to environmental conditions in the region which has been established through many generations of natural selection. Much supporting evidence is available for the above figures, as a result of observations on the reservation, where improved sheep have consistently failed to withstand the environmental conditions like the native Navajo sheep. Crossbred types have performed quite satisfactorily in years of good feed, but when more rigorous conditions are imposed by scanty rainfall and short feed, the Navajo sheep have not been affected so adversely as the crossbreeds.

TABLE 13.SUMMARY OF PRODUCTIVITY OF NAVAJO AND CROSSBRED EWES IN EXPERIMENTS AT FORT WINGATE, NEW MEXICO. Nine Years 1937-45 Three Years 1943-45 Navajo Crossbred Navajo Crossbred No. ewes bred 2516 2304 569 882 No. ewes lambing per 100 ewes bred 88.1 83.5 86.5 75.7 No. lambs born per 100 ewes bred 116.3 109.2 128.1 100.6 No lambs born per 100 ewes lambing 131.9 130.8 148.2 132.8 No. lambs weaned per 100 ewes lambing 113.5 107.5 117.9 99.8 No. lambs weaned per 100 live lambs born 89.1 83.5 80.0 76.0 Av. weaning weight per lamb (Kg.) 26.2 27.8 27.3 28.5 Lamb produced per ewe bred (Kg.) 26.2 25.0 27.8 21.6 Lamb produced per ewe lambing (Kg.) 29.8 29.9 32.2 28.5

61 Figure 28. A portion of the experimental flock at the Southwestern Range and Sheepbreeding Experiment Station, Fort Wingate, New Mexico. The flock is shown grazing on one of the typical range areas used by the Station. Photo by Milton Snow, Navajo Service, Window Rock, Arizona.

These observations indicate that sheep having more than 1/2 improved blood are not apt to perform satisfactorily under the environmental conditions of the region. Wool produced in the crossbred lines has not conformed to the type most desirable for hand weaving. The average diameter of fibers in samples from crossbred ewes in 1945 ranged from 21 to 31 microns at the side, and from 24 to 34 microns at the thigh. Twenty-five percent of the side samples were classified as fine wool (70's-64's), 48 percent as half blood (60's and 58's), 23 percent as three-eighths blood (56's), and only 3.5 percent as quarter-blood (50's and 48's). These results are not surprising since the Navajoewes used in the development of these lines showed some evidence of Rambouillet blood, and the purebred rams used had wool that was predominantly of three-eighths blood type. This, together with the fact that the undercoat of the old-type Navajo sheep is quite fine, has resulted in the production of fleeces finer than those best adapted to hand weaving. Another contributing factor has been the selection pressure exerted against outercoat, kemp, and other medullated fibers.

62 Wool from the Navajo lines is also becoming too fine for most efficientuse in hand weaving. Studies of the fleece samples from the yearling Navajo ewes in 1945 revealed that 8.7 percent of the side samples had average diameters comparable to fine wool, and percentages comparable to one-half, three-eighths, and quarter-blood wool were 70.6,14.7,5.8,respectively. Selection pressure against outer coat, kemp, and other medullated fibers has reduced the proportion of these coarser fibers and resulted in the production of fleeces somewhat finer than are desired. This project is continuing, with emphasis on selection and other breeding measures to produce fleeces of the desired quality, and to provide suitable breeding rams for use on areas of the reservation specializing in the production of hand-weaving wool. A portion of the experimental flock and its range is shown in Figure 28.

Figure 29. A typical Ossimi ram, native to Egypt. Photo provided by Mohamed Ali Bey El-Kilany.

63 Improvement of Native Sheep in Egypt The Ossimi sheep (Fig. 29) is one of several native types in Egypt. It is rather small, mature ewes weighing approximately 45.5 to 54.5 Kg. (100 to 120 pounds). The meat is lean, and fibrous in full-grown animals. The wool is white and is classified as carpet wool in world markets. It is straight, has very little grease, and average fleeces weigh 1.4 to 1.8 Kg. (3 to 4 pounds). An experiment has been conducted by Sidky (1947) to test the possibilities of improving these sheep through crossing with the Suffolk (Fig. 30). The Suffolk was selected because it combines good mutton form with medium- quality wool, and since there was some indication that the Suffolk might be able to survive under conditions existing in Egypt. Two Suffolk rams were imported. One died of an accident, and some difficulty was encountered in inducing the second ram to mate. For about six months he exhibited no signs of sexual desire. Once this difficulty was past a new difficulty arosethe ram was unable to copulate because of the fat tail of the Ossimi ewe. It was finally necessary to dock about 50 mature ewes so the crosses could be made.

Figure 30. A Suffolk ram used in crossbreeding experiments in Egypt. Photo provided by Mohamed Ali Bey El-Kilany.

64 The native ewes were part of a flock maintained at the Ministry of Agri- culture Farm at Sakha for utilizing crop-aftermath. Theywere not outstanding, but were considered representative of the native sheep. The crossbred animals (Fig. 31) performed quite satisfactorily, andgrew much more rapidly than the native Ossimi sheep. Differences in growth ratesare illustrated by the data on average weights at variousages up to six months, presented in Table 14. The meat of the crossbreds was superior in quality to that of the natives; the difference in general structure and fat distribution is shown in the cross-sections of muscles from the two types, Figure 32. There was also some improvement in the quality of the wool, that of the crossbreds being somewhat finer and having some crimp, as compared with the relatively straight, coarse wool of the native sheep. Also, the wool extended over the bellies of the animals, which are generally bare in the Ossimi type.

Figure 31. A Suffolk X Ossimi crossbred sheep produced in the experiments in Egypt. Photo provided by Mohamed Ali Bey El-Kilany.

65 Figure 32. Photographs of comparable muscles from Ossimi (left) and Suffolk X Ossimi (right) sheep. Note the superior development of muscling and the marbling in the meat of the crossbred animal. Photo provided by Mohamed Ali Bey El-Kilany.

TABLE 14.WEIGHTS OF OSSIMI AND SUFFOLK XOSSIMI SHEEP AT VARIOUS AGES, AT SAKHA, EGYPT. Ossimi Suffolk X Ossimi Age Male Female Male Female (kilograms) Birth 3.0 3.2 4.1 4.1 1 month 8.2 8.2 11.6 10.0 2 months 12.3 13.4 17.3 15.9 3 months 19.1 18.9 26.4 23.2 4 months 25.5 24.1 35.2 31.1 5 months 30.5 27.3 43.2 37.3 6 months 32.5 29.5 45.7 38.6

66 III AD `APTABILITY OF CATTLE TO TROPICAL AND ll,FITROFiCAL CLIMATES Man has frequently tried to transplant improved cattle, and particularly specialized dairy stock, to areas where the environment differs materially from that in their native home, or from other places where they have performed satisfactorily. The results have often been unsatisfactory, sometimes disastrous. This has been true particularly in the lower areas of the tropics, whichare generally characterized by high temperatures, high rainfall during portions of the year, coarse roughage, limited grain feeding, and insect pests. Improvement of environmental conditions is an objective of every progressive livestock producer. But in many areas limitations are laid down by nature, so that the producer can progress only to a certain point in improving, within economic limits, the supply of feed and other environmental factors. In tropical and subtropical areas, many of the conditions under which cattle must be produced are determined by nature, and if a producer's cattleare to perform profitably he must select and breed animals that ftre adapted to the environment. Ability to withstand a hot environment may be determined by studying the animal's immediate reaction to high temperatures, as measured by increases in respiration rate and in body temperature, and by measuring productivity in terms of reproduction, growth, milk production, and beef production. Some of the available information on these subjects is summarized in the following sections. Animals are o f two general types insofar as their heat-regulating mechanisms are concerned: cold-blooded and warm-blooded. In the cold-blooded animal, the body temperature is adjusted to that of the environment, and may vary over a wide range as the atmospheric temperature varies. The warm-blooded animal, on the other hand, can tolerate only relatively small variations in body temperatures, and its physiological reactions are tuned to the task of keeping heat production in the body and heat loss from the body in balance, or nearly so. Under tropical and subtropical conditions, the ability of the animal to keep heat production balanced by heat loss is often taxed to the utmost. Animals that have an efficient heat-regulating mechanism are therefore more apt to survive and to perform satisfactorily than those that are. not so efficient. There is considerable evidence that the zebu cattle of India (Bos indicus) and their relatives are superior to European cattle (Bos taurus) in their ability

67 to maintain a normal or nearly normal body temperature under tropical and subtropical conditions. In work conducted by the United States Bureau of Animal Industry (Rhoad, 1938), it was found that the bodytemperature and respiration rate of cattle rose and fell during thecourse of a summer day. One of the avenues of heat loss from the body is evaporation through the lungs, so an increase in respiration rate speedsup the loss of heat from the body. The temperature and respiration rate of zebu cattlerose less than that of Furopean cattle (Aberdeen Angus) when exposedto high temperatures. European cattle became feverish when exposed to direct sunlight insummer under subtropical conditions in Louisiana, while zebu cattlewere not so affected, Zebu X Angus crossbred anirnalswere intermediate to the parental strains in their ability to maintain a normal body temperature ina hot environment. There was an indication that greater efficiency of the heat-regulating mechanism might be partially dominant. Another indication of the superior heat-regulating ability of zebu cattle is found in their grazing habits on hot, sunny days. Under these conditions zebu cattle have been observed to continue grazing during rnuch of the day, while Angus cattle spent most of the time in the shade. Crossbredswere intermediate in this respect. A formula has been devised (Rhoad, 1944) for calculating the heattolerance of cattle, in an attempt to express this rather complex physiologicalvalue in a single figure. The simplified procedurewas devised so that results could be recorded easily under field conditions. Testsare made on bright summer days when atmospheric temperatures in the shadeare between 85° and 95° F. Tests could also be made under conditions of highertemperatures, providing such conditions generally prevail inan area. The cattle to be tested are placed in a temporary wire enclosure, builtover sod, shortly after sunrise. They are free to move about, and have water available. At 10A.M. the animals are placed without undue distUrbance ina nearby chute and rectal temperatures are 'obtained. Respirations per minute are also observed by counting-movements of the flank. The animals are then returned to the wire enclosureand kept there until 3 P.M., when the respirationsand body temperaturesare again observed. Both morning and afternoon dataare included in the averages for each animal. Halter-broken and quiet cattlecan be tied to a fence or to posts, and data obtained without placing them ina fenced enclosure or chute. It is important that animals be observedwhen away from buildingsor other obstacles that would offer shadeor obstruct wind rnovement. It is also important that they be placed over sod, since pavedor unsodded corrals would modify considerably the natural climaticconditions to which the animalsare

68 subjected. After observations are made, heat tolerance is computed according to the following formula: 100(10 (BT-401.0) ) in which BT is the average body temperature obtained under conditions of the test; 101.0 is the normal body temperature of cattle; 10 is a factor to convert degrees of variation in body temperature to a unit basis; and 100isperfect efficiencyin maintaining body temperature at 101.0° F. By use of this formula, an individual or group of cattle withan average body temperature of 103.8° F. under the conditions of the test would have a heat-tolerance coefficient of: 100(10 (103.8-101.0))100(10 (2.8))=-100-28=72. Data collected at the U. S. Bureau of Animal Industry's experimental farm at Jeanerette, Louisiana, showed the heat tolerance for the breeding groups recorded in Table 15. Some data have been obtained on various breeds and one crossbred group of cattle in Greece that indicate variations between the breeding groups in heat tolerance. These data are summarized in Table 16. The groups compared were Jersey, Holstein, Ziguet X Brown Swiss, and Brown Swiss. The Jersey and Holstein animals were newly imported, the Brown Swiss had been in Greece for one year, and the Ziguet X Brown Swiss animals were bred in Greece.

TABLE 15.SCALE OF HEAT TOLERANCE FOR CATTLE AS DETERMINED BY THE IBERIA HEAT TOLERANCE TEST' AT JEANERETTE, LOUISIANA, IN 1944

Numbers Coefficient Breeding Sex of heat Animals Tests tolerance

Zebu F 7 18 89 IA Zebu M Angus F 19 67 84 % Zebu % Angus F 8 21 84 Santa Gertrudis F 7 21 82 M AfricanderIA Angus F 22 64 80 Jersey F 34 34 79 34 Zebu VI Angus F 54 165 77 Grade Hereford S 12 12 73 I/1 Africander % Angus F 4 9 72 Angus F 31 69 59

'Average morning temperature 90.0°F., relative humidity 82.8 percent, wind velocity 2.1 miles per hour. Average afternoon temperature 93.2°F., relative humidity 71.7 percent , wind velocity 4 .5 miles per hour.

69 These results °cannot be considered as conclusive evidence of superior heat tolerance in the Brown Swiss and Ziguet X Brown Swiss cattle since the environmental temperatures at which tests were made were somewhat lower than in the Jersey and Holstein groups, and these differences may haVe been sufficient to distort the results. This illustrates one of the basic weaknesses of any field test which cannot be carried out under conditions where major factors influencing the outcome can be kept uniform for all animals tested. The apparent superiority of the Jersey over the Holstein is of particular interest, however, since similar results have also been obtained in studies by Seath and Miller (1947) in Louisiana. These workers studied milking cows in two separate dairy herds at Louisiana State University. The studies were made during 1944 and 1945. The animals studied in 1944 included 36 Holsteins and 16 Jerseys, those in 1945 included 41 Holsteins and 27 Jerseys. A total of 26 sets of observations were made during a period of thirteen weeks in 1944, and 15 sets of observations were made in 1945. Air temperatures during days of observation varied from 65° to 93° F., and averaged 81.1° in 1944. In 1945 the range was from 750 to 91° F., with an average of 85.6°. Recordson the animals were taken from 10 to 30 minutes after the cows entered the milking barn at approximately 3 P.M. and before they were fed grain. Respiration rates were obtained by counting flank movements; body temperatures were taken with veterinary thermometers inserted approximately 3 inches into the rectum; pulse rates were counted by placing the tips of the fingers next to the coccygeal arteries on the underside of the tail. The results of the work in Louisiana showed that during 1944 the body temperatures of the Holsteins averaged 103.3° F., while those of the Jerseys averaged only 102.6° F. In 1945, the average for the Holsteinswas 104.5° F. as compared with 103.7° F. for the Jerseys. Differences between breeds in respiration and pulse rates were small and were not consistent in thetwo years. Minimum or normal body temperatureswere about the same for the two breeds, but higher maximum temperatureswere registered by the Holsteins. Body temperature increased more rapidly in Holsteins than in Jerseysas a result of increases in air temperature. On hot days, Holsteincows frequented wet spots in the shade and would lie in mud and water; theycame to the milking barn in the evening covered with dirt and mud. Jerseysshowed little tendency to do this. The results obtained by Seath and Miller (1947)are in agreement with earlier results by Freeborn, Regan, and Berry (1934), whofound that Hol- steins exhibited higher body temperatures than Jerseysat air temperatures of 75°, 80°, and 85° F. The bodytemperatures reported for Jerseys by Seath

70 and Miller are similar to those found by Gaalaas (1945) in Louisiana for the same atmospheric temperatures. Seath and Miller (1947) also studied the reaction of the Holstein cows to air temperature changes on the basis of the amount of white on the sides and backs of the animals. They failed to find any relationship between the amount of white and heat tolerance, but concluded that any tendency in his direction was probably overshadowed by other, more important factors. Further evidence of the importance of adaptability under tropical and subtropical conditions is found in the effects of shade and sprinkling on Jersey cows, as reported by Seath and Miller (1947). Four grade Jersey cows were observed during ten relatively warm days when the air temperatures varied from 83° to 90° F., and relative humidity was between 61 and 80 percent. Body temperatures of cows after exposure to sunshine for two hours averaged 102.66° F., and removal to shade (dry) resulted in reductions of 0.34° and 0.74° F. after 0.5 hour and 1 hour, respectively. Sprinkling of cows (with original body temperatures of 102.53° F. after being in the sun) reduced body temperatures by 0.54° F. after 0.5 hour in the shade, and by 1.08° F. after 1 hour in the shade. In the latter case, the cows had temperatures that are considered normal. Respiration rates were reduced to levels that averaged lower after 0.5 hour than after1 hour in the shade. Cows not sprinkled showed a respiration rate of 83 per minute in the sun, and an average decrease in rate of breathing of 27.2 at the end of 0.5 hour and of 25.2 after 1 hour in the shade. Cows sprinkled before entering the shade had much greater reductions in rate of breathing than did non-sprinkled cows, i.e. 49.4 less after 0.5 hour and 41.6 less after 1 hour. Reductions in rate of breathing for non-sprinkled cows versus those sprinkled favored the latter group by 81 percent at the end of 0.5 hour and 65 percent after 1 hour in the shade. Average reduction in pulse rate for non-sprinkled cows after being in the shade 0.5 hour was insignificant (0.8 per minute) but was significant (3.6) after 1 hour. Cows when sprinkled showed decreases in pulse rate that averaged 6.1 after 0.5 hour and 6.6 after 1 hour. Either shade alone or sprinkling followed by shade was found effective in reducing body temperature, respiration, and pulse rate of dairy cows, and the second procedure was found to be more rapid and more effective in causing animals to approach readings which are considered normal. The high heat tolerance index for Brown Swiss cattle recorded in Table 16 indicates that this breed may have special adaptability to hot climates that is not possessed by other breeds developed in the temperate zone. Further studies of this breed under tropical and subtropical conditions should be carried out.

71 TABLE 16. HEAT TOLERANCE 01' CATTLE IN GREECE' Place Breed Numberanimals of Numberof daystested TemperatureFahrenheit humidityRelative Air velocitymeters per minute tolerance Iberiaheat Piraeus Jersey 10 3 A.M.86.5 P. M.88.3 A.M. P.M.34 36 A.M. P.M. 57 108 index 84 VetanicesAghia Eioussa Agricultural School ZiguetHolstein X Brown Swiss 1010 23 84.988.9 83.592.7 4340 4930 128 94 241 99 9376 Vetanices Agricultural School 'Data obtained by Richard Allman in connection with 'United Nations Relief and Rehabilitation Administration work. Brown Swiss 10 2 84.9 83.5 43 49 94 99 92 The reasons for superior heat tolerance or heat-regulating ability in certain twes of cattle, and particularly in zebu or part-zebu animals, are not well understood. Itis probable that several factors are involved. The extra skin of the zebu's dewlap and sheath may provide a greater amount of surface per unit of body weight, thus providing a greater opportunity for loss of heat from the body. There may be basic physiological differences, but little information is available on this point. Color of the coat is also a factor. In a study of various colors, Rhoad (1940) reports that lighter cattle reflect more of the rays of the sun, and therefore absorb less heat. For example, white zebu cattle, light fawn Jerseys, dark fawn Jerseys, and black Aberdeen cattle ranked in that order in the amount of sunlight reflected. Similar results were obtained in South Africa by Bonsma (1943), who studied the amount of sunlight reflected from Afrikander and Jersey cattle, animals possessing several shades being included for each of the two breeds. Comparisons were also made of animals of various breeds with contrasting colors. Wide variations were observed, and the lighter animals reflected ..the most sunlight. Riemerschmid and Elder (1945), also working in South Africa, approached this problem by a different method. These workers determined the "mean effective absorptivity" of cattle coats of different colors. The mean effective absorptivity is a measure of the relative amount of heat produced at the surface of the hairy coat by conversion of radiant energy into heat. This is expressed in percent, and is always somewhat under 100, since the animal body is rounded and beams of light hit only a portion of an exposed side at right angles. The mean effective absorptivity was found to be 49for a white Zulu animal, 78 for a red Afrikander, and 89 percent for a black Aberdeen Angus: more heat is formed at the surface of the darker-colored animal. Thickness of coat may also be a factor in heat-regulating ability, since the northern breeds of cattle usually have heavier coats than zebu cattle. The rate of hair growth may also be an important factor in detei mining adaptability to hot climates. French (1946), working at Mpwapua, Tanganyika, investigated rate of hair growth on zebu, Ankole, 3/4 Ayrshire-1/4 zebu, and 3/4 Holstein-1/4 zebu animals, all of comparable ages. The slowest rate of growth was observed on zebu, though there was little difference between them and the indigenous Ankole stock. The rate of growth was considerably higher in 3/4 European animals. There was little difference between the animals having Ayrshire and Holstein blood, but in the few animals studied there was an indication that Ayrshire cattle might grow hair faster than Holsteins; this point needs confirmatibn by study of larger numbers of animals. French also observed a tendency to faster hair growth in animals having woolly

73 coats. These results are of particular interest inthe light of Bonsma's (1943) observation that animals with woolly, as compared with glossy, coats showed greater increases in body temperature andrespiration rate as the atmospheric temperature increased. Still another factor may be the ability to sweat, since this is one of the important avenues of heat loss from the body. Little is known of the sweating ability of various types of cattle, but Kelley(1932)examined sections of some skins. In a microscopic field of 0.8 square millimeter, he found an average of9.33sweat glands in the skins of one-half zebu cattle, and an average of

5.25glands in the satne area of skin of one-fourth zebu cattle. In the skin of a Holstein-Friesian, there were only a few glands and these were difficult to find. Supporting data on the importance of color in relation to heat absorption have been obtained on humans. Various types of skin rank as follows in their ability to reflect sunlight, according to Blum(1945):Fine white, average blond, dark brunet, Hindu, and Negro. The amount of reflection varied from45 percent in fine white skin to16to19percent in Negro skin. Blum points out that the importance of heat absorbed from the sun's rays, which he calls the solar heat load, can best be understood by comparing it with the amount of heat produced in the body (the metabolic heat load). In the human, the maximum solar heat load may be two or three times the resting rnetabolic heat load (which is about96kilocalories per hour) or about equal to the metabolic heat load of ordinary walking (which is about265kilocalories per hour). Obviously, variations in the amount of heat absorbed from the sun are important in determining the ability of a man or animal to withstand high environmental temperatures. When considering the reactions of cattle to high temperatures, it is interesting to look back into the evolution of our present-day types of cattle. Many of the steps in evolution are a matter of conjecture. The evidence that has been pieced together indicates that at one time the cattle population was concentrated largely in South-Central Asia. In the process of evolution from that time, cattle differentiated into two main types, the aurochs and the zebu. The aurochs cattle spread over middle and. northern Europe, including Russia, while the zebu cattle spread over southern Asia, along the northern shore of the Mediterranean, and over Africa. The domestic breeds of cattle developed in Europe and Great Britain are descended largely from cattle of the aurochs type, while the various types and breeds of humped or zebu cattle have descended from the original zebu type.

74 The distribution of present-day cattle types and breeds shows that the native Jr indigenous types in the h;gher or cooler latitudes descended from the aurochs while those in the lower or warmer latitudes are descended from the zebu.The dividing line between the two types varies somevvhat with geographic and climatic conditions, but approximates 30' N. and 30' S. of the equator. Around the Mediterranean, and in sotithwestern and southern Asia, cattle of the zebu type are found as far north as 40° latitude. Along the borders between the two types of cattle, much blending has undoubtedly taken place. For example, the countries along the northern shore of the Mediterranean have native cattle that are short-haired and zebu-like in appearance, but are normally without humps. Another example of such blending is found in China. The native cattle of the south 'have sizable humps, although they are not nearly so large as some humps seen in India. Farther north in China, the humps become smaller, and the Mongolian cattle of the north have none. Some interesting observations on the cattle of Ceylon have been reported by Wright (1945). He mentions tour general types of cattle on the island: European breeds, crossbred stock, Indian breeds (Sindhi and Sahiwal), and theindigenousSinhalabreed.Thelatterconstitutebyfarthe largest portion of the island's cattle.They are of zebu type, have a moderately developed hump, short hair, pigmented skin, and are usually either black or red. The hump and the dewlap are usually well developed in the male, w-hich is used largely for light draft purposes and is considered an ideal animal for cart work. The udder of the female is small and underdeveloped, and the milk yield is correspondingly low. The general conformation, however, is not unsuited to milk production, since the barrel is reasonably large in well-fed stock and the animals are docile when accustomed to handling. The animals are small, the height at wirhers seldom exceeding 107.7 cm.(42 inches). The :omparative productivity of the various types is indicated by the average figures in Table 17.

TABLE 17.AVERAGE FIGURES ON MILK PRODUCTION BY VARIOUS TYPES OF CATTLE IN CEYLON.1 Number of cows from which the Average yield average is of milk per Breeding of cows calculated lactation European breeds 110 1704.54 Kg. Crossbred stock 134 1477. 27 Kg. Indian breeds (Sindhi and Sahiwal) 121 1136.36 Kg. Indigenous Sinhala breed 60 363.63 Kg. 1 Wright (1945)

75 90 UNSUITABLE FOR EUROPEAN BREEDS LLI80,.o Co ombo Anuradhapura Kandy EUROPEANACCLIMATIZATION BREEDS POSSIBLE OF 7 70°F Badulla Diyatalawa 60 65°F Nuwara- El iya Hakgala 50 EUROPEANSUITABLE BREEDS FOR 2 FEET 1000 2000 3000 4000 5000 6000 Figurebased 33. on Relationobservations between in seven mean localities annual in temperature Ceylon.IV ETERS and 305 elevation above sea level, 610 ELEVATION 9/5 1220 /525 After Wright (1945). /830 These figures appear to indicate that Europeancattle and crossbreds might be aelapted for milk productionin such an area. However, their level ofpro- duction under these conditions is low, and it shouldbe strongly emphasized that European cattle suffergrave disabilities in a tropical environment. This renders them quite unsuited for milk productionexcept in very limited areas and under very specializedmanagement. The inadequacy of the heat-regulating mechanism of European cattle when maintained undertropical conditions has already been discussed. Attention has also been calledto the need for large amounts of good quality feed if highly specialized dairy animalsare to perform efficiently. In Ceylon, most animals haveto subsist on a relatively sparse diet derived mainly from roadside and jungle grazing. Anumber of diseases are also prevalent in Ceylon to which indigenous zebu cattleshow marked tolerance, but to which European cattle are highly susceptible. These diseases include foot and mouth disease, redwater fever, and anaplasmosis.European cattle have been maintained with reasonably satisfactory resultsas a source of milk on up-country tea estates in Ceylon. Wright (1945) has made some useful observations on the conditions under which it may be assumed that European cattle might be satisfactorily raised and maintained. He points out that European cattle will only thrive where the mean annual temperature falls below 65° to 70° F. Themean annual temperature in low- and mid-altitude areas of Ceylon markedlyex- ceeds 70° F. In one location where the elevation is 1222 m. (4,010 feet), the mean annual temperature is 68.2° F. It is only in areas above 1524 m. (5,000 feet) that conditions suitable for European breeds prevail. A chart (Fig. 33) shows the relationship between annual temperature and elevation in Ceylon. The very limited area to which European cattle may be adapted is indicated by the fact that only 1 percent of the whole area of Ceylon lies above 1524 m. (5,000 feet), and that only 5 percent lies above 914 m. (3,000 feet). It is evident that the possibilities for expanding milk production by the use of European cattle are very limited. Wright (1945) sees a possibility of predicting the adaptability of cattle to an area other than their native home. He points out that the combined effects of seasonal variations in temperature and relative humidity can be depicted by a "climograph," in which the mean levels of temperature and relative humidity are plotted for each month, in order, and the resulting points joined to form a composite figure. Wright (1945) has made further interesting observations on the conditions that may contribute to dwarfing of animals, in which he has made use of the climograph. The Sinhala cattle indigenous to Ceylon are small in size;

77 90 cc 80 COCHiN''1 ANURADHAPURA!! eto 1. '...KUAL A RENGGAN I 1i t i / CA LCU T TAi IDADAN >-2o_ 70 65 i \i\ --JoH 60 50 30 40 50 60 70 80 90 andMalayaFigure Nigeria 34. (Kuala Climographs (lbadan). Trenggani), for thefive West typical Coast dwarfing of Madras (Cochin), Bengal (Calcutta), MEAN MONTHLY RELATIVE HUM IDI TY (%) areas: Ceylon After Wright (1945). (Anuradhapura), DELHI (SAHIWAL BREED)

90 IL o

IX 1- 80

2 I- 70

_J65 °60

NUWARA ELIYA

2 50

30 40 50 60 70 80 MEAN MONTHLY RELATIVE HUMIDITY (%) Figure 35. Climographs for four localities in Ceylon, two localities in India, and one in Great Britain. After Wright (1945). water buffaloes in Ceylon also tend to be small. Similar dwarfing occurs in parts of India, particularly in Bengal and on the west coast of Madras Presi- dency, in Malaya, in Nigeria, and other West African territories. Such dwarfing appears to be a normal result of the hot, humid climate that prevails in wet tropical areas. Climographs for five such areas are shown in Figure 34; they are quite similar for each area. The wide variation that can exist in climographs is illustrated in Figure 35, differing markedly from those in the previous graph. Two studies have been conducted that shed some light on the extent to which heat tolerance in cattle may be inherited. Seath (1947) tested jerseys and Holsteins involving 52 cows by 7 sires in 1944, and 68 cows by 8 sires in 1945. He was investigating the heritability of heat tolerance as indicated by variations in body temperature and respiration rate. Twenty-one cows included

79 in the study for both years showed correlations between average records for 8 warmer days (on an intra-herd basis) of 0.37 for body temperature and 0.64 for respiration rate. The records for 8 warmer days gave a repeatability for individual body temperature records of the same cow of 15.2 percent for 1944 and 38.5 percent for 1945, as compared to 8 percent and 6.7 percent for the 2 years when all observation days were used. In like manner, respiration rates were more highly repeatable when the records for warmer days only were used. The ranking of sire progeny groups by years showed a great similarity for the 2 years, although there was discrepancy between rank on the basis of body temperature and that for respiration rate. Some sire groups ranked high on one basis and low on the other, and vice versa. Estimates of heritability of individual records based on sire-progeny differences were for body temperatures 15.1 percent and 30.9 percent for the 2 years, and for respiration 76.6 percent and 84.3 percent. Figures for respiration appear out of line, as they greatly exceed the estimates of repeatability, and the reverse condition was expected. Body temperature appears to be a safer measuring stick for heat tolerance than respiration rate. Seath's (1947) estimate of heritability of body temperature (15 to 30 percent) isin line with that found for individual production records o f cows. In practice this would mean that the offspring from parents selected because of their tolerance to heat would be expected to retain from 15 to 30 percent of the advantage the parents had over the average for the herd of breed. The use of more than one record appears to increase progress through selection. If the average heritable portion of variance of two heat tolerance records is 20 percent, then progress through selection would increase by 29 percent when using two records as compared with one record, 58 percent when using four, and 83 percent when using eight records. The data summarized aboveon heritability cannot be accepted as conclusive, since, if this character follows the pattern of many other economically important characters in livestock, results obtained on different herds and under other circumstancesmay vary rather widely. Similar studies on other herds are desirable. Gaalaas (1947) studied records obtainedon a Jersey herd at Jeanerette, Louisiana, and concluded that not much change occurred in theaverage heat tolerance of the herd from year to year. A definite difference in heat tolerance was found in different age groups, the two-year-olds showing" the lowest average and the three-year-olds the highest. The coefficient of heat tolerance was found to be a reasonably stable individual characteristic in animals four years of age and above, but it was not in animals of two and three years of

80 age. A real difference in the physiological response of different cows to the same environment was found when measured by the body temperature. The stage of lactation and gestation had little, if any, material effect on the coefficient of heat tolerance. Some differences were found in theresponse of groups of daughters by various sires, when measured at two and three years of age, but little difference was found when measured at fouryears of age or more. At first glance, it might appear that this finding tends to contradict Seath's report, in which a fairly high heritability of heat tolerance was found. It is quite possible, however, in this herd study by Gaalaas, that only minor differences in sires existed, and that there was a heritable basis for variations in heat tolerance, even at four years of age and over.

Adaptability as Measured by Milk Production Experience in India has shown that high-grade and purebred animals of European dairy breeds such as the Holstein do not produce satisfactorily under conditions that generally prevail in that country. Many of the animals become thin. "Panters," or animals that breathe rapidly and laboriously during hot weather, are frequent. Inability to withstand the hot climate is reflected in their milk production. Average production figures on the better-managed farms that were doing constructive breeding work, for animals with varying amount of European blood (mostly Holstein), as published by the Imperial Council of Agricultural Research (1941), are shown in Table 18. Instead of the level of milk production being increased as the amount of imported blood is increased beyond the level of 1/2 to 5/8, there is an actual decrease, even though the genes for milk production have presumably been increased by the introduction of more Holstein or other blood of dairy breeds. These data, accumulated under variable conditions in several parts of India, bring out the importance of resistance to a tropical environment if milk production is to be satisfactory.

TABLE 18.AVERAGE PRODUCTION OF CATTLE IN INDIA CARRYING VARIOUS AMOUNTS OF IMPORTED BLOOD, MOSTLY HOLSTEIN-FRIESIAN. Number Average amount Breeding of cows of records of milk (Kg.) imported blood 21 2199.54 1/4 imported blood 175 2719.09 1/2 imported blood 589 3171.36 % imported blood 204 3175.00 3/4 imported blood 396 3029.09 imported blood 86 2809.09

81 Figure 36. A native "yellow" cow of Szechwan Province, China, used in the Chungking Dairy at Chungking, Szechwan.

Figure 37. A 1/2 Holstein-1/2 Szechwan nativecow in the herd of the Chungking Dairy, Chungking, Szechwan.

82 Results of this type will not necessarily apply to all tropical and subtropical areas. The high summer temperatures in the plains of India place an unusually heavy strain on animals not adapted to hot environments, and such rigorous conditions do not prevail in all regions. For example, in the province of Szechwan in southern China, the summer temperatures are not nearly as high as they are in India, and clouds give considerable protection from the sun during much of the _summer period. Data obtained under these conditions indicate that grading-up to approximately the level of purebred Holsteins may be satisfactory. The data (Table 19) were obtained in the Chungking Dairy by T. C. Liang, and are summarized by Phillips, Johnson, and Moyer (1945). TABLE 19.SUMMARY OF MILK PRODUCTION DATA IN THE CHUNGKING DAIRY, CHUNGKING, SZECHWAN, CHINA. Lactation period Milk yield (Kg.) Fat Lacta- Breeding No. tions Long Short Average(Mature basis) Yellow cow 10 13 203 27 104.7 '119.5 5.92 1/2 Holstein 54 166 530180 329.8 2342.2 4.74 3/4 Holstein 20 27 575259 386.1 2985.4 3.90 Holstein 9 17 639276 418.2 4180.4 3.63 1 Range WaS13.9to284.1Kg. Four animals produced in the work at Chungking are shown in Figures 36-39. These animals are in good condition compared with the Jersey cow

Figure 38. A3/4Holstein-1/4 Szechwan native cow in the herd of the Chungking Dairy, Chungking, Szechwan.

83 illustrated in Figure 44, produced in experimental work in Jamaica.

Adaptability as Measured by Beef Production The effect of environment on beef production is more difficult to measure than on milk production, because there is no definite and single yardstick with which to measure beef production. The United States Bureau of Animal Industry and the Texas Agricultural Experiment Station conducted a co-operative study (Black, Semple, and Lush, 1934) in which zebu-Hereford and zebu-Shorthorn steers were compared with Hereford and Shorthorn steers with respect to feedlot performance, market desirability, size and weight of various parts of the body, and characteristics of the meat. No significant differences were found in the total quantities of feed consumed in proportion to weight of the steers. The crossbreds, however, took a longer time to eat their feed, ate considerably more grain and cottonseed cake and a little more roughage, per 45.5 Kg. (100 pounds) of gain in weight, than did the Hereford and Shorthorn steers. Steers containing zebu blood were heavier at weaning time than Hereford and Shorthorn steers, and at that time would have returned considerably more money per head. The price per hundredweight was slightly higher for the crossbreds, in addition to their advantage in weight. After 120 days of feeding in dry lot, the crossbred steers sold at slightly higher prices per hundredweight and returned more per head, even though their feed costs were slightly higher. After feeding periods ranging from 150 to 179 days in length, there was a tendency for this situation to be reversed. No signiacant differences were found in the amount of shrinkage while the animals were being shipped from feedlots to market. On account of smaller gains, greater feed consumption, and only slightly greater margins between purchasing and selling prices per hundredweight, the Crossbreds were not so desirable as feeders as the Herefords and Shorthorns, if purchased at the same price, under the conditions of this experiment. How- ever the differences in feedlot performance were small. The crossbreds had, on the average, smaller heads, larger hides, and smaller digestive tracts. The larger hides are explained by their loose and pendulous character, especially around the neck. The smaller digestivetracts offer an explanation for the tendency of the crossbreds toeat less at a time and to eat more frequently than the purebred steers. The crossbred steers averaged 2 to 4percent higher in dressing percentage than the Herefords and Shorthorns. The dressedmeat from the purebreds

84 Figure 39. A 7/8 Holstein-1/8 Szechwan native cow in the herd of the Chungking Dairy, Chungking, Szechwan. was appraised at a slightly higher figure than that from the crossbreds, but this was about offset by the higher dressing percentage of the crossbred steers. Rib cuts from the crossbred steers had a slightly higher proportion of edible meat and a correspondingly smaller portion of bone than the rib cuts from the other lots. There were no consistent differences in the chemical composition of the edible portions or in the color of the meat.Samples of cooked meat from the crossbred and the Hereford and Shorthorn steers were graded by a committee, which found only slight differences in palatability. The textui e of the meat from the crossbreds was rather consistently coarser, and was judged to be slightly less tender. Taking into consideration the various factors in cooking and palatability, and the varying tastes of the judges, the cooked samples of meat from crossbred, Hereford, and Shorthorn steers were considered to be approximately eqiral in quality. Considerable work has been conducted by the U. S. Bureau of Animal Industry to determine the type of breeding best adapted to beef production in the coastal plain around the Gulf of Mexico, where high temperatures and humidity prevail during much of the year. This work has been carried out at the Iberia Livestock Experiment Farm at jeanerette, Louisiana (Fig. 40). Some of the results, which have been reported in detail by Rhoad and Black (1943), are given below.

85 Figure 40. Experimental pastures at the Iberia Livestock Experiment Farm at Jeanerette, Louisiana. These pastures are typical of much ofthe grazing area on low and relatively wet land adjacent to the Gulf of Mexico.

Zebu, Aberdeen Angus, Afrikander, F1ereford, and Shorthorn bulls were used. The females were native stock, grade Herefords, purebred Angus, and several generations of progeny of these females and bulls of the types used in the tests. Comparisons were based on weights at birth, at six months, and at two years of age. The procedure that gave best results when Hereford bulls were used on native and grade Hereford foundation cows was to mate these females to the Hereford bulls, then mate their female offspring to zebu bulls. The hybrid females were then mated to Hereford bulls, producing offspring that were of 5/8 Hereford, 1/4 zebu, and 1/8 foundation breeding. When the Angus cows were used as foundation female stock (Fig. 41), best results were obtained by first mating these cows to zebu bulls, then backcrossing the hybrid heifers to Angus bulls, thus producing 1/4 zebu-3/4 Angus offspring (Fig. 42). Good results were also obtained with animals having 3/8 zebu-5/8 Angus blood. These were produced by mating- first- generation heifers (1/2 zebu-1/2 Angus) to bulls having *1/4 zebu-3/4 Angus blood, or by mating second generation heifers (1/4 zebu-3/4 Angus) to hybrid bulls. Other animals having varying amounts of zebu blood alsogave reasonably satisfactory results. The work indicates that the amount of zebu blood needed in beef cattle to give them sufficient adapability to the environment in the coastal plains around the Gulf of Mexico, lies somewhere between 1/4 and 1/2, but sufficient data have not yet been accumulatedto determine the proportion

86 Figure 41. An Angus cow and five offspring resulting from polyallel crossing at the Iberia Livestock Experiment Farm, Jeanerette, Louisi- ana. AAberdeen Angus cow. The five offspring were produced from matings with bulls of the following breeding: BAberdeen Angus. CZebu. DZebu X Angus. EAfrikander. FAfrikander X Angus. The dam was photographed at four years of age and the other animals at about 18 months, except F, which was photographed at two years of age.

87 ';.

Figure 42.Three weanling heifers having3/4Angus and 'A zebu blood. These heifers wereproducted at the Iberia Livestock Experiment Farm, Jeanerette,Louis- iana.

that can be expected to give the best results, particularly in a continuing breeding program. Another phase of the work conducted by the U. S. Bureau of Animal Industry in the coastal plains area has been summarized by Rhoad, Phillips, and Dawson (1945). A study was made on certain of the data collected at Jeanerette, Louisiana, to determine the relative merits of the offspring of Aberdeen Angus cows when mated to Angus, zebu, Afrikander, and zebu- Angus bulls. The zebu bulls used in this and other work at Jeanerette were primarily of the Kankrej type, but there was also a trace of Gir blood. (These and other breeds and types of Indian zebu cattle are described briefly by Phillips, 1944.) The breed of sire was found to be significantly associated with birth weight of calves when the four types of bulls were mated to the same nine Angus cows. The calves ranked as follows in birth weight, by types of sire: zebu, Afrikander, zebu-Angus, and Angus. In a group of 19 cows mated to three types of bulls, birth weight was also significantly associated with the breed of sire; the calves ranked, by type of sire, as follows: zebu, Afrikander, and zebu- Angus. The breed of sire was also found to be significantly associated with weight at six months, in an analysis in which Angus, Afrikander, and zebu bulls were involved. This significant variation was largely due to the relatively small size of the Angus calves as compared with those sired by thetwo other types of bulls. Calves sired by zebu bulls were only slightly heavier than those sired by Afrikander bulls. In another study in which offspring of zebu, Afri- kander, and zebu-Angus bulls were used, the calves ranked in that order in

88 weight at six months, but the variation among the averages of the three groups was not large enough to be statistically significant. Data on a _limited number of zebu-Angus and Afrikander-Angus cows as dams indicated that offspring of the zebu-Angus cows were somewhat lighter at birth but heavier at six months of age than those from Afrikander-Angus cows, but these results cannot be considered conclusive since the two groups of cows were mated to bulls of different types. The findings indicate that hybrid calves carrying zebu or Afrikander blood are superior to Angus calves out of the same Angus cows under conditions prevailing in the coastal plains area at Jeanerette, Louisiana, as measured by weight at six months of age. The difference between calves sired by zebu and Afrikander bulls was not so clear cut, but the averages were in favor of those sired by zebu bulls.

Observations in Northern Australia Tropical and subtropical conditions in northern Australia impose hardships on European cattle, and some attempts have been made to introduce zebu cattle into these regions. Kelley (1943) has reported on the results thus far obtained. He points out that there were a number of earlier importations of zebu cattle into Australia, but that serious attempts to use these cattle did not begin until 1933, when an importation was made from theUnited Stdtes. The animals imported were of three zebu types: Ongole (Nellore), Kankrej (Gujerat), and Gir. They were distributed to several ranches in Queensland between 17° 23" and 22° 36" south latitude, where they were used for crossing with British cattle and were maintained under practical ranching conditions. It was not possible to obtain detailed experimental data, but the breeders reported on the performance of these animals in relation to 2.nimals of British origin, and the results shed some light on the usefulness of zebu and crossbred animals. The animals had not been maintained sufficiently long at the time of Kelley's report to determine their longevity. However, it was observed that mortality rates among crossbreds were about 30 percent lower than among British breeds. This figure is based on general observations. The areas where the cattle were studied are sometimes subject to severe droughts, but none occurred during the period of observation. Two herds were subjected to semi-drought, in one area, and the general impression was that crossbred cattle were more tolerant to the situation than the British herds. Severe losses and high infantile mortality were observed among British cattle on ranches in the neighborhood.

89 There is a dry period during the winter of every year in this reg,ion. Cross- bred cattle were observed to maintain themselves in better condition during this period than British cattle, a matter of importance to successful cattle production in the area. During the summer, zebu and zebu X European cattle were observed to remain out in bright sunlight, either resting or grazing, while British cattle sought the shade. This observation is identical with that reported by Rhoad (1938) in Louisiana. On one occasion respiratory rates of crossbreds and of British-bred cattle were observed. The shade temperature at the time was 101.5° F. The cattle were driven from 4.0 to 6.4 Km. (21/4 to 4 miles) and placed in yards where they could be observed. All animals were in excellent condition. The animals observed included two- and three-year-old Shorthorn and Devon X Shorthorn bullocks, and two-year-old zebu X Short- horn bulls. Under the conditions outlined, the British-bred bullocks were panting, and various counts showed their respiratory rates to be approximately 150 per minute. No such acceleration was apparent in zebu X Shorthorn

Sorne observations were also made on tick repellence of zebu X European crossbred and European animals. It was observed that, although a small number of halfbreds may be relatively susceptible, most half and three-quarter zebus harbor few ticks and seldom, if ever, show tick worry. The repellence of ticks appears to be closely associated with the length and character of the coat. When the coat was of zebu type, short-haired and sleek, repellence was good. When the coat was of the long-haired British type, tick infestation occurred, and tick worry resulted in some animals. However, tick worry was not as pronounced in animals carrying quarter zebu blood as it was in British-bred cattle under the same conditions. Animals carrying three-eighths zebu blood seldom exhibited tick worry. Some observations were made on carcasses of animals carrying zebu blood, including those sold to packers and those examined in carcass tests: In general, the crossbred animals showed high dressing percentages, acceptablecarcass formation and finish, and fine texture of muscle. The evidence accumulated in this study has shown that zebu X European crossbred cattle yield greater returns than British-bred cattle under comparable conditions. The results also indicate that the percentage of zebu blood in crossbred stock is of considerable importance, and that somewhere between 25 and 50 percent of zebu blood is necessary to give adaptabilityto the hot environment in Northern Queensland.

90 Observations in Jamaica and Trinidad European dairy animals have been taken intoboth these areas and have been used for crossing with the hope of improvingthe local animals. Some zebu animals have also been imported and havebeen used for crossing with the European stock. Hammond(1932)concluded that the main problem to be solved in Jamaicawas to determine the proportions of zebu and European blood that would give the best results. He alsoexamined the cattle breeding work in Trinidad, and concluded that, although work hadbeen initiated in 1879, very little improvement could be expected from the nondescriptanimals a vailable. Bulls of the Shorthorn, Red Polled. Guernsey, Jersey, and Holstein breeds had been usedon native and zebu cows, and Holstein-Friesian bulls had given best results,as measured by local requirements, which were for cows that could be milked and bullocks that could be used for work. He also pointed out that the chief problem in Trinidad,as in Jamaica, is that of determining the proportion of Holstein-Friesian and zebu blood requiredto give the best results under local conditions. Edwards(1932)made a further study of the results obtainedon the Govern- ment Stock Farm at Hope, Jamaica, in which he examined the influence of six bulls introduced for improvementpurposes. The milk records of the progeny of these bulls were examined on an individual basis, and also in relation to percentage of zebu blood. European animals maintainedon the farm had low average milk yields and a high percentage of these animals showed poor constitutional adaptability to tropical conditions. Animals containing 1/2 zebu blood produced about the same amount of milk, and there was an equally high percentage of poor producers, but it was believed that these animals lacked the genetic ability to produce large amounts of milk. Highest milk yields were observed among grade animals possessing1/32to 1/4 zebu blood, and the lowest percentage of failures was observed among this group. Edwards concluded that animals containing approximatelythese amounts of zebu blood might be the most satisfactory base from which to develop a new milking breed adapted to the environment. The experiments with the crossing of zebu and European cattle at Hope, Jamaica, which were dealt with by Edwards(1932)and Hammond(1932), have been analyzed more closely by Howe (1946). The data he used were collected during the years 1910-1940 inclusive. He points out that the breeding work was undertaken in 1910 with the objective of developing a type of animal which would combine resistance to tropical conditions with an economical pro-

91 duction of milk. In the original work, purebred or high-grade animals were used, the main breeds being Ayrshire, Brown Swiss, Guernsey, Holstein, Jersey, and Red Polled. It was found that when such breeds were crossed, the hybrids were little better than the pure animals, neither having the necessary resistance to tropical conditions. In 1914, two zebu breeds, the Nellore (Ongole) and the Hissar, were introduced for crossing with the dairy breeds, but the progeny were unsatisfactory as dairy cows. This is not surprising, since the breeds used are not among the better dairy types of zebu cattle. These breeds were used until 1922. In 1920, some Sahiwal cattle were imported from India, and were crossed with the Guernsey, Holstein, and Jersey breeds, with the object of developing a type of animal suitable to conditions in Jamaica. This zebu breed was used exclusively for crossing work after 1922. Howe shows that, for -Various reasons, the Ayrshires, Brown Swiss, and Red Polled were less satisfactory for dairy purposes than Guernsey, Holstein, and Jersey breeds; only these three breeds were used during the later years of the experimental work. The animals were grouped for comparison as follows:

Amounts of Euro pean blood Group By ei ghths By sixteenths Breeding 16/16 Purebreds 8/8 15/16 II 7/8 14/16 13/16 Three-quarter breds III 6/8 12/16 11/16 IV 5/8 10/16 9/16 Half-breds 4/8 8/16 In all instances the amount of European blood possessed by the animals used was as set out in the various groups. All the animals listed which were not purebred contained some zebu blood. In some instances, however, the amount of zebu blood contained did not equal exactly the difference between the fraction of European blood and unity, the amount lacking by 1/16 or 2/16 of zebu blood. The remainder of the inheritance in these cases came from grade crows of mixed breeding, mainly of European breeds and possessing no zebu blood. The numbers of animals used in the study are set forth in Table 20.

92 WEIGHT Kg. Lbs. 500.0 1100

454,51000

409.0 900

363.6 800 .0" 3/8.0 700

2727600

227.2 500 /8 /.7400 -- Purebreds /36.3300 Three-quarter Breds 90.9200 Half - breds i I 45.4 I 00 22.7 50 BIRTH I 2 3 4 5 6 7 8 9 10 AGE IN YEARS FAO Chart No 173

Figure 43. Growth curves for purebred Jerseys and Guernseys, and for animals containing approximately 3/4 and 1/2 European blood under conditions at Hope, Jamaica. From Howe (1946).

TABLE 20.NUMBERS OF ANIMALS USED IN STUDIES IN JAMAICA.'

Groups European breed involved IV V Total Jersey 260 63 120 201 46 690 Guernsey 48 26 86 154 64 378 Holstein 5 27 42 45 119 Totals 308 94 233 397 155 1,187 1 Reported by Howe (1946).

93 TABLE 21.WEIGHTS IN KILOGRAMS BY AGE IN YEARS OF PUREBRED AND ZEBU CROSSBRED CATTLE. Age in Groups years II IiI IV V Jersey Birth 23.2 22.7 24.5 25.0 27.7 1 166.8 151.8 148.2 175.5 202.3 2 250.0 243.2 241.8 266.4 296.8 3 325.9 325.0 305.5 347.7 351.8 4 338.6 345.9 355.9 385.5 397.7 5 363.2 345.9 367.7 395.0 386.4 6 366.4 375:0 360.0 402.3 455.5 7 375.0 397.7 384.1 365.0 453.6 8 380.0 404.5 388.6 431.4 427.7 9 390.5 457.3 411.4 420.9 450.0 10 391.8 360.0 365.0 418.6 434.1 11 410.9 390.9 365.0 302.7 420.0 12 446.4 365.0 267.3 456.4 13 470.9 365.5 358.2 518.2 14 550.0 15 504.5

Guernsey Birth 25.0 26.4 26.8 28.2 30.0 1 179.5 163.6 162.7 201.4 195.9 2 282.7 250.9 293.2 290.5 298.6 3 337.3 313.6 364.1 354.1 363.2 4 384.1 354.5 400.0 399.5 395.0 5 390.0 342.7 420.9 413.2 458.2 6 425.9 350.0 400.9 420.0 442.3 7 421.4 388.2 486.4 429.1 8 451.4 417.7 420.5 9 475.9 452.3 422.7 10 478.2 390.9 11 507.3 12 481.8 13 463.6 14 454.5 15

Holstein Birth 30.0 31.4 30.9 31.8 1 183.2 136.4 177.3 2 303,2 265.5 277.3 3 362.7 377.7 367.3 4 448.2 420.0 5 454.5 468.2

The average rate of growth in the various groups is shown in Table 21, and a summary of the growth rates of the larger composite groups is presented in Figure 43. Three animals produced in these experiments are shown in Figures 44, 45, and 46.

94 TieV .)

Figure 44. A purebred Jersey cow used in experimental work at Hope, Jamaica. This was a second generation animal in Jamaica,was six years old when photographed, and weighed 376 Kg. (828 lb.).

After Hammond(1942).

Figure 45. A zebu-Jersey heifer produced in the experimental work at Hope, Jamaica. This animal had 9/32 zebu blood, was four years old when photographed, and weighed 479 Kg. (1,054 lb.).

95 TABLE 22.AVERAGE PRODUCTION OF MILK IN KILOGRAMS BY BREEDS AND GROUPS FOR 305-DAY LACTATION OF CATTLE AT HOPE, JAMAICA.' Groups Stand- Breed ard Breed II III IV avgs.error Jersey 1827.31889.11450.91747.3 2054.51816.8 18.2 Guernsey 1613.21501.81803.21817.71815.01764.1 19.5 Holstein 1700.0 2320.02217.32502.7 2337.3 48.2 Group average, all breeds 1789.51772.31855.51829.5 2090.0 1 From Howe (1946).

The average milk production in the various groups is given in Table 22, together with the averages for the three breed groups, classified according to the type of European blood they contained. The average percentage of butterfat in the milk of the various groups is shown in Table 23. The results of this study, which are summarized above, show that animals with zebu blood have a higher birth weight and grow more rapidly than purebred animals of the European breeds, the rate increasing with an increase in

Figure 46. Azebu-Jersey cow produced in the experimental work at Hope, Jamaica. This animal contained 17/32 zebu blood,was six years old when photographed, and weighed 527 Kg. (1,160 lb.). After Hammond (1942).

96 TABLE 23.AVERAGE PERCENTAGE OF BUTTERFAT IN THE MILK OF CATTLE AT HOPE, JAMAICA.' Groups Stand- Breed ard Breed I II III IV V avgs. error Jersey 4.89 5.08 5.22 5.40 5.89 5.18 .03 Guernsey 4.85 4.99 5.18 5.09 5.27 5.11 .04 Holstein .. 3.47 4.16 4.18 4.42 4.25 .06 Group average, all breeds 4.89 4.99 5.08 5.13 5.18 From Howe (19.16). the amount of zebu blood. The difference in growth rate is more perceptible after two years, and, at maturity, halfbreds weighed on the average 81.4 Kg. (179 pounds) more per head than purebreds. Milk production also increased as the amounts of zebu blood increased, the greatest production being given by halfbreds. The differences between groups were significant in the Holstein stock, and highly significant in the Jersey and Guernsey stocks. The halfbred Holstein's produced 802.7 Kg. (1,766 pounds) more milk per lactation, than those with 1/8 zebu blood, there being no purebred Holsteins reported in this study. Among Jersey and Guernsey stock, the increase in production of the halfbreds over the purebreds was 227.3 Kg. (500 pounds) and 201.8 Kg. (444 pounds) per lactation, respectively. These results indicate that animals with V zebu blood are the most suitable for milk production. However, the high production in the halfbreds may be due, to a considerable extent, to heterosis, and further experimental work is necessary before definite conclusions can be reached on the amo-unt of zebu blood that would be most effective. Howe suggests that such work should include inter se matings of halfbreds, and the production of animals by crossing halfbreds with cattle having 3/8 and 5/8 zebu blood. Records on animals having amounts of zebu blood greater than half should also prove valuable in determining the optimum amount of zebu blood. The percentage of butterfat in the milk increased with an increase in the amount of zebu blood. The Jersey X zebu stock showed the greatest increase in butterfat, their milk testing 1 percent more than the purebreds. The increase in fat percentage of halfbreds over purebreds in the Guernsey stock was 0.42 percent, and in the Holsteins the halfbreds were .095 percent higher than animals having 1/8 zebu blood. Differences between groups were significant in the Holstein stock, highly significant in the Jersey stock, and not significant in the Guernsey stock.

97 Observations were also madeon certain other production factors, which may be summarized as follows:

The number of services per calfwas slightly reduced as the amount of zebu blood increased. Differences in thisrespect were highly significant in the Jersey stock, but not significant in the Guernsey and Holsteinstock. The age at which heifers calved for the first time increased with theamount of zebu blood. The differences in this respectwere highly significant in the Jersey stock, and not significant in the other twotypes. The length of the dry period increased with the addition of zebu blood, butnone of the differences was significant. The length of the service period increased with increasein the amount of zebu blood. This period was calculated by subtracting 283 days, or the average length of the gestation period, from the interval between calvings. None of the differences was significant, however. The length of the gestation period increased as the amount of zebu blood increased, but these differences were not significant, with the exception of the Jersey stock, where they were found to be highly significant. Howe concludes that halfbred animals are superior for dairypurposes under conditions that exist in Jamaica. Comparisonswere not possible with animals containing more than half zebu blood; and Howe believes that additional experimental work is needed before definite conclusionscan be drawn as to whether the halfbreds are the most desirable for maximum milk production and resistance to climatic and disease conditions. Howe also observes that while the Holstein stock showed the greatest milk production per lactation, the Jersey stock had a higher butterfat test at an earlier age, and shorter dry and service periods. He concluded that these factors, combined with other observations, show the Jersey animals to be better adapted to conditions in Jamaica. He adds that Holsteins are not able to maintain themselves in as good condition as Jerseys and that Guernseys vary when crossed with zebus.

Results in Tunisia Efforts to improve dairy cattle in Tunisia have been described by Ducloux (1930). Native cattle, zebu, and French dairy breeds were used. As a result of these tests, Ducloux is of the opinion that, for North Africa, 40 percent of zebu blood is essential to combine disease resistance and milking ability in one animal.

98 Development of the Santa Gertrudis Breed in Southern Texas, U.S.A. ln connection with several of the accounts of cattle breeding in tropical and subtropical areas, mention has been made of the need for determining the amount of zebu blood required to ensure adaptability under various circumstances and of the possibility of developing new types containing the required proportions of zebu and other blood. The Santa Gertrudis breed is an example of one such undertaking that has been carried sufficiently far that the resulting type is now considered a definite breed. Santa Gertrudis cattle were developed on the King Ranch in southern Texas under the supervision of Robert J. Kleberg, Jr. The King Ranch is in the coastal plain region of southern Texas, where the summers are long and hot, and where internal and external parasites are major problems in the production of range cattle. Little grain is available here for fattening, and the area is too far removed from the Corn Belt to make the marketing of feeder steers a major part of the local cattle industry. Therefore the marketing of reasonably fat animals from grass is the major objective. If it is to succeed, the animals must be adapted to the utilization of range grass under subtropical conditions. It must also be remembered that much of the income from the range-cattle enterprise is from the marketing of discarded heifers and older cattle. If these discarded animals, and particularly the older ones, are to yield a satisfactory income, they must be able to stand up well in the environment. The earlier cattle of Mexico were first introduced from Spain and were commonly known as Longhorn cattle (Fig. 47). These were the first cattle introduced into Texas, and the only ones available in the early days. They were, therefore, the first cattle used on the KingRanch. They did reasonably well on the range, were prolific and hardy but small, inclined to be wild, and did not mature into desirable beef animals. In an effort to produce more beef per acre, and beef of better quality, the Longhorns were graded up by means of Hereford and Shorthorn bulls. Small herds of registeredHereford and Shorthorn cattle were also maintained. The grading-up process was continued until the entire ranch was stocked with high-grade or purebred animalsapproximately 25,000 Shorthorns and 25,000 Herefords. Kleberg states that the two herds, FIereford and Shorthorn, were placed on the ranges to which they were best adapted. The two breeds were kept separated, and comparisons were made from time to time. Experience proved that on the better, stronger lands the Herefords were more prolific, better rustlers, and fattened more readily into a smoother carcass of beef which

99 ,

,:`* c404/.1"

s1t

dO 4 '''s., ''''otr*, 'oo'4'kes'''''V A 4,,,J6, 4 '

.,'' 34' $

to.,44:" A 4,,,e.

r, 444

44,,...1; ' ' ^:41' 's §..,..0$ o O'' o o '

Figure 47. An example of the early Spanish-type (Longhorn) cattle used on the King Ranch in southern Texas, U.S.A.

Photos provided by Robert I. Kleberg,

Figure 48. This bull, named Monkey, was used in development of the Santa Gertrudis breed.

, »

100 usually commanded a higher price per pound. They were, however, somewhat lighter in weight than the Shorthorn, and when placed on the sandy and weaker lands of the ranch, tended to deteriorate faster, to produce small- boned calves, to suffer more from cancer-eye, screw worms, and so on. The standard of excellence of the Shorthorn cattle was much easier to maintain on the open range. However, the Shorthorn suffered more during periods of protracted drought, and often produced very poor calf crops during unfavorable seasons. Both of these British breeds suffered tremendously from flies and mosquitoes after heavy rains. During very wet periods, the young calves, and oftea the mature cattle in the herd, were literally eaten up by screw worms. Ticks lodged in great quantities in their ears, causing screw-worm infection. In some of the brush country during these intervals of wet weather, the calf crop was reduced to as low as 40 percent. After some preliminary experience with the crossing of zebu and European cattle, Kleberg set out to develop a new type combining, insofar as possible,

Figure 49. Some grass-fed Santa Gertrudis cattle on the KingRanch in southern Texas, U.S.A. Photo provided by Robert J. Kleberg,

101 the desirable characteristics of zebu and British-type beef cattle. Zebu animals of the Ongole (Nellore) breed were selected for crossing with the Shorthorn cattle on the King Ranch. Kleberg (1931) has described the procedures used in developing this breed. As in all such undertakings, success depends somewhat upon the laws of chance that operate in animal genetics. The breeding quality of individual animals produced from a specific cross cannot be pre- dicted. In the work on the King Ranch, one outstanding bull resulted from mating a zebu bull to a high-grade Shorthorn cow that carried either 1/16 or 1/32 zebu blood. This bull, named Monkey (Fig. 48), sired a second outstanding animal called Santa Gertrudis. The dam of Santa Gertrudis was 1/2 zebu and 1/2Shorthorn. These two outstanding bulls, upon which the breed was based, contained approximately 1/2 zebu and 1/2 Shorthorn blood. Large numbers of animals have been used in the development of the existing herd and detailed information has not been published concerning all the breeding work. However, Kleberg (1931) indicates that many bulls containing 3/8 zebu and 5/8 Shorthorn blood were being used on cows of similar breeding to establish the range herd; the objective was to establish a breed containing these proportions of the blood of the two parent types. The 52 original zebu bulls involved in the undertaking belonged to different breeds of zebu cattle and their mixtures. The best individuals available were selected, belonging to the Ongole (Nellore), Krishna Valley, Kankrej (Gu- jerat), and Gir types. Many of the animals showed some traces of Sindhi blood. Some of the resulting Santa Gertrudis cattle are shown in Figure 49. Kleberg (1931) reports that steers of the new breed averaged 34 to 46 Kg. (75 to 100 pounds) heavier at one year of age and about 68 Kg. (150 pounds) heavier at two years of age than animals of the British breeds maintained under identical range conditions.Heifers averaged about 46 Kg. (100 pounds) heavier and mature cows from 46 to 68 Kg. (100to 150 pounds) heavier than females of the European breeds. Kleberg says that the animals have performed very satisfactorily under the range conditions of southern Texas, and that the steers have been marketed primarily as grass- fat stock. Four-year-old Santa Gertrudis steers have averaged approximately 636 Kg. (1,400 pounds) when finished on grass for market, dressing about 3 percent higher than animals of the British breeds.Kleberg also reports that old cows and bulls have been marketed to better advantage than those of British breeds, since they have consistently outweighed the British-bred animals and have maintained themselves in better conditionon the range. He emphasizes that, in reporting thesuccess of the Santa Gertrudis

102 breed, he intends no criticism of the British breeds, whichare superior cattle under favorable conditions. However, under conditions in southernTexas, there are definite advantages in favor of animals havingsome zebu blood.

Work in South Africa

Bisschop (1938) has studied the reactions of animals under conditionsat Armoedsvlakte, neat Vryburg, in British BeChuanaland, South Africa. Three exogenous breeds were included in the investigation, the Sussex for beef production, the Red Polled fot beef and milk production, and the Holstein (Fries) for milk production only. Afrikander animalswere also used, repre- senting the only systematically improved. indigenous breed. A basic herd of nondescript native cows was graded up, using the four breeds mentioned above. In 1925, large-scale experiments .wete initiated to deterMine.. the effects of feeding bone meal on the groWth,- production, and reproduction of cattle at Armoedsvlakte. The results proved that , phosphorus is one of the chief limiting factors to animal functioning -under the environmental conditions there. When phosphorus was fed the Aftikander grade cattle were able to perform satisfactorily, but the excilgenons breeds were not sufficiently adapted to perform normally undet. the environmental conditions, and therefore underwent some phenotypic changes. The soils upon which these animals were m.aintained are sandy, loose, and very shallovv. They overlie a deep layer of tufaceous limestone, through wh:ch plant nutrients in rolutiont pass down beyond the reach of the plant roots. The soils have become eXtremely poor in phosphoric acid. The basic liMiting factor in the environment, however, is the low rainfall, which averages 16 inches a year. The dissipating effects of evaporation and other causes reduce this by at least 60 percent, leaving only about 6.4 inches of moisture for plant growth. The poor soils and the inadequate rainfall result in a sparse vegetation, which supplies a complete ration for cattle for only a few m.onths during the year. The grazing is dry, unappetizing, deficient in phosphates and proteins, and probably defiCient in valuable carbohydrates during at least seven months of each year. Further climatological factors such as high altitude, marked seasonal and diurnal variations in temperature, low relative humidity, and high intensity Of 'infra-red and ultra-violet light rays add to the difficulties of normal animal function. The limiting influences of animal diseases have been overcome to a considerable extent by prophylactic measures.

103 TABLE 24. ATCOMPARISON THE LAMSIEKTE OF WEIGHTS RESEARCH AND STATION, MEASUREMENTS ARMOEDSVLAKTE, OF MATURE NEAR ANIMALS VRYBURG, OF VARIOUS SOUTH AFRICA.TYPES OF BREEDING 1 2 Actual Average Weights (Kg.) and Measures3 (cm) 4 5 6 7 8 9 10 11 12 Basic herd BreedingAnimals of Animals No.46of Weight470.5Live Length146.1Body of WithersHeight126.0 at HeightHook-bones128.8 at DepthChest69.1 of WidthChest34.1 of betweenWidthHook-bones48.6 between°WidthThirls42.4 LengthRump 50.0 of betweenWidthbones12.1Pin- Heart-177.6Girth LengthHead50.2 of betweenWidthEyes17.7 X IAAfrikanderHolstein... HolsteinAfrikander 18171516 470.0486.8488.6521.4 149.0156.1145.2148.1 130.5133.3128.3129.6 131.9134.6131.2132.2 67.270.969.1 32.233.532.631.8 47.849.050.553.7 47.948.441.041.9 48.852.049.851.7 18.816.312.611.8 180.4176.7180.5180.8 54.352.750.251.9 18.518.418.3 XlA IA SussexRedSussex Red Polled Polled 10201917 485.0509.1435.5472.7 146.6152.4144.7151.7 122.1128.1124.1130.2 124.7130.6124.21`d1.4 65.970.468.269.8 -- 32.933.631.831.9 49.647.952.150.2 44.544.242.144.1 49.351.948.750.9 15.411.913.7 179.3179.2175.5177.0 48.149.350.951.7 18.118.918.318.2 X IAAfrikander Afrikander 3.493.86 1.37 12.861.83 Differences12.641.86 in Percent over Basic Herd 0.002.60 -16.74 0.82 -1.17 23.40 -2.48 4.13 1.801.58 28.1724.98 3.393.95 X IAHolsteinRed HolsteinRed Polled Polled -17.44-0.09210.82 0.48 -0.62 23.8326.841.98 23.3312.4125.79 12.4124.502.02 --12.75 '2.601.01 -16.45-7-5.57-1.76-4.40 -1.65210.49 13.9113.29 -3.30212.98214.15 4.01 -2.4-0.40 24.00 1.8 213.22255.37234,71 -0.51-1.18-0.34 1.63 -24.18 12.990.003.39 14.5213.953.392.82 XIA SussexSussex 'Highly significant 28.213.09 2Significant -0.96 24.310.34 -23.10 -13.18 -14.63 -1.51 -23.57 1.67 1.40 -1.30 -16.74 1.88 - -3.52-1.47 -1.44 -0.71 -12.6027.202.06 14.9514.25 -1.40 23.80 -1.65227.27 0.960.90 -1.79 1.39 26.782.26 Pasture and animal managementsystems in this ranching area are still crude and primitive.Bisschop (1938) reportson observations on three generations of experimental animals under such conditions. Thesegenerations include the basic herd of nondescript nativecows and the 1/2 and 3/4 grade animals produced by gradingup with bulls of the four breeds already mentioned. The indigenous Afrikander grades showedno changes either in body weight or body shape from the basic herd through the halfbredto the three- quarter-bred generations. Theexogenous breeds, however, showed changes between each generation. In general, the changes from the basic herdto the halfbred generation were progressive, but from the halfbredto the three- quarter-bred generation, theywere markedly retrogressive and in many cases fell below the level of the cows in the basic herd. Weights and various body measurements of the animalsare summarized in Table 24. Bisschop concludes that under the Armoedsvlakte environment, corrected bythe feeding of the phosphorus supplement, the indigenous grade animalsare able to attain ancl.maintain a phenotypic makeup typical of the Afrikander animals. Grades produced by crossing withexogenous types, however, are unable to attain and maintain the phenotype that would be possible undera more favorable environment. The specific changes Bisschopreports are outlined as follows:

In the Afrikander grade herd, the only important change that occurredwas an increase in the length of head. This change was due to the broader characteristic of the Afrikander and was not considered an environmental modifica- tion. In the Holstein grade herd, the halfbreds were heavier, deeper, and taller than the animals in the basic herd, and approached the Holstein breed characteristics with respect to large frame and general conformation. The 3/4 Holstein animals were shorter, narrower, had less depth of body, and weighed less than the halfbreds, although they retained the same height. They were leggy, shallow, narrow, and lean in comparison with both the halfbreds and the cows in the basic herd. The Sussex grade animals reacted in a very different way. The halfbreds showed a marked increase in weight, but no important changes in height, length, or width, in comparison with cows in the basic herd. The general tendency was towards compactness and beefiness. The 3/4Sussex animals retained the beefiness, but were somewhat smaller as measured by weight, length, and depth. The grade Red Polled animals reacted in a fashion intermediate to the Sussex and Holstein grades. The halfbred animals showed a tendency towards

105 body build of the dairy type, but the1/4 bred animals showed some of the reduction in size typical of the beef type. However, they became very lean, as did' the three-quarter-bred Holsteins.

Figure 50. Bhutla ponies used by Himalayan tribesmen in Bhutan and adjacent parts of India. The ponies shown in this picturewere rented to vacatiomsts for pleasure riding in the city o": Darjeeling.

106 IV OBSERVATIONS ON THE ADAPTABILITY OF HORSES AND SWINE The discussions on adaptability haveso far dealt primarily with sheep and cattle, the two kinds of animals upon whichman primarily depends for the utilization of large areas of grazing land. On suchareas, which are not suited to intensive agriculture, these animals are able to turn the available forage into meat, wool, hides, and milk (particularlyamong nomadic and semi- nomadic groups) for human use. In general, cattle utilize the better grazing lands and sheep the less productive areas, but practicesvary widely. Cattle are also used extensively as work stock in many parts of the world, particularly in tropical and subtropical areas.Cattle are also used primarily for milk production, or attempts have been made to introduce them for this purpose, in many parts of the world where environmental hardships place definite limitations on livestock production. It is natural therefore, that much of the available information on adaptability has been obtained from studies and observations on cattle and sheep. Horses and swine are also kept under a wide variety of conditions, but most of the technical developments and studies on these animals have been in areas where the environment is reasonably favorable to livestock production. However, limited information is available on less favorable areas, and a few examples can be given to illustrate the importance of adaptability.

Adaptability in Horses

Anyone familiar with various types of horses cannot fail to be impressed by the wide differences in size and by the general tendency of greater size to be associated with favorable environments, particularly a good feed supply. Horses in mountain and semiarid regions are generally small.Examples can be found in the highlands of Scotland, the Indian foothills of the Himalayas (Fig. 50), the Tibetan highlands, the hills of southern China, the semiarid and highland plateau regions of northern China (Fig. 51), the semiarid regions of Arabia and adjacent countries. The large draft horses native to Belgium, France, and the intensive farming regions 6f Great Britain (the Belgian, Percheron (Fig. 52), Clydesdale, and Shire breeds) constitute a sharp contrast, not only in size, but in unsuitability to conditions such as

107 those in which aSi kong horse must exist. Unfortunately, practically no scientific data are available to show variability in performance of these and other types of horses under different conditions. However, some information on the growth of horses under western (U.S.A.) range conditions has been reported by Dawson, Phillips, and Speelman (1945) and these workers have also compared their findings with those of others who studied the growth of horses under more favorable conditions. A summary of this material should, therefore, serve to indicate the problems encountered in improving horses under difficult environmental conditions. The work was conducted at the U. S. Range Livestock Experiment Station at Miles City, Montana, where a uniform system of breeding, feeding, and management was followed for the horses used in the study. The system included: (1) Mating of mares, three years of age and over, to foal in the month of May, whenever possible; (2) weaning of the progeny when about six months old; (3) inspecting and measuring all growing stock twice annually (about April 15 and October 15); (4) keeping foals with dams on pasture without supplemental feed until weaning; (5) feeding weanlings throughout the winter on adequate rations of grain and hay (about 0.45 kilo or one pound of grain for each 45.5 Kg. (100 pounds) of body weight plus all the hay desired); (6) carrying all growing stock betweenone and three years of age on range pasturage except in emergencies; (7) carrying non- working mares on range pasturage without supplemental feed except in emergencies; (8) feeding working mares and geldings enough during work periods to maintain fit condition; (9) maintaining stallionson feed at headquarters throughout the year, except light stallions kept on range during the breeding season. Growth data were reported in this study on 297 horses foaled from 1927 to 1934, inclusive. Of these, 16 were Belgians; 59 were grade-draft horses (ranging from one-half to nearly pure Belgian); 75 were Morgans; and 147 were classified as grade-light horses. Some of the last group were sired by Thoroughbred stallions; others by Morgan stallions; anda few by a grade- Standardbred stallion. The mares used to produce the grade-light horseswere, for the most part, western saddle stock of unknown breeding, butmany obviously carried some improved light-horse blood, and thisgroup also included offspring of a few Morgan mares mated to Thoroughbred stallions.

All the draft horses were sired by one Belgian stallion. This horse hada height of 169.2 cm. (66 inches-16 hands 2 inches) anda weight of 840.9 Kg. (1,850 pounds) when in good breeding condition. Four Thoroughbred stal-

108 Figure 51. A Mongolian horse of the type found in Chinghai Province, China, on the northern portion of the Tibetan plateau. lions were used. They ranged from 431.8 to 556.8 Kg. (950 to 1,225 pounds) in weight and from 157.7 to 165.4 cm. (611/7to 641/2 inches) in height. Detailed data were available on three of the four Morgan stallions which ranged from 472.7 to 522.7 Kg. (1,040 to 1,150 pounds in weight and 155.8 to 160.3 cm. (6w/4 to 621/2 inches) in height. The fourth Morgan stallion was sold before attaining mature size, after siring only a few colts. The same Morgan stallions were used to sire the Morgans and part of the grade-light horses. With one exception, only one stallion of a breed was used in any one year, so it was impossible to compare the progeny ofdifferent sires within the same breed and year. The fact that the same sire was used for the Belgian and grade-draft groups undoubtedly tended to make those groups more alike than if different sires had been used. A similar likeness existed between the Morgans and grade- light horses sired by the same Morgan stallions. The Morgan stallions used at Miles City were similar in breeding to those used at the United States Morga.n Horse Farm, Middlebury, Vermont, with which certain of the data were compared. Two were sired by Mansfield (7255 A.M.R.), a stallion used extensively in the stud at Middlebury, and two

109 were his grandsons. The mares at the two stations were not so closely related, but the breeding of the young stock appeared sufficiently comparable to justify comparison of growth rates under the widely different environments of the two places. As judged by comparison with the results of other investigations, data obtained on the animals in this study showed that they grew normally with adequate rations, from birth to weaning and from weaning to one year. They grew normally also in the 12- to 18-months period, w,hen generally they received sufficient feed from summer pastures. Between 18 months and two years of age, that is, during the first winter, they had to depend entirely on the range; all groups lost from 6 to 101 pounds on the average. The following summer all groups gained rather rapidly, but lost again during the third winter. Generally, the same fluctuation was found in the fourth and fifthyears, but it was not as great and did not occur in all groups. The growthcurves are shown in Figure 53. Since the number of horses at the differentages was not

Figure 52. A Percheron stallion illustrating the large drafttype typical in the better farming areas of North America andEurope. Other large breeds of importance include the Belgian,Clydesdale, English Shire, and Suffolk. Such large types couldnot exist and perform satisfactorily under the conditions where Bhutiaponies, Mongolian horses, and other such small types are used.

110 1,600 GRADE DRAFT de BELGIAN d d 1,500 BELGIAN 99 - GRADE DRAFT 99 1,400

1,300 -1,200 g1,100 - 0 .MORGAN dd 0- -GRADE LIGHT d d -1,000 - --v-GRADE LIGHT 99- ---x-MORGAN 99 I 900 - Ili 800 -

700

600

500

400 6 12 18 24 30 36 42 54 AGE (MONTHS)

Figure 53. Growth in weight of horses under range conditions in Montana, U.S.A., by breed groups.

After Dawson, Phillips, and Speelman (1945).

Figure 54. Growth in height of horses under range conditions in Montana, U.S.A., by breed groups.

65 GRADE DRAFT dd 64 4-BELGiAN - -0-GRADE DRAFT 9 9- 63 ---BELGIAN 99 62 -0 ----- 0------4.-GRADE LIGHT dd.- ./ X"-MORGANcrcr 61 V

60 ..------9GRADE LIGHT 9 9 -- v 59 ---- ..4' x ...../- ..------x.-MORGAN 99 -- .."-"----.-7-- x, ----- 58 ... - - L.) /''''.' ,x- - - - -x-- / 57 // (D 56 z LT1 55

49 60 12 IB 24 30 36 42 48 54 AGE (MONTHS)

111 2.000 DRAFT HORSES (CRAMPTON'S DATA) 1.900

1,800

1.700

1,600 PERCHERON dd+99 COLuMWA, MO) 1,500 *--<__GRADE DRAFT 99 1,400 GRADE DRAFT dc3 ( MILES CiTY, MONT ) ( MILES/ CITY MONT 1.300 o A o1,200 a. 1,100 MORGAN 99 71MIZLEBuRY,VT) -0 1,000' DRAFTD HORSES LTJ. (HARPER'S DATA) X- 900 MORGAN 99 (MILES CITY, MONT.1 800 'X' 700 600

50 40 6 12 24 30 36 42 48 54 60 AGE ( MONTHS) Figure 55. Growth in weight of range-fed horses vs. growth in weight of horses fed liberally under farm conditions.

Data are from Crampton,1923;Harper,1921;Trowbridge and Chittenden, 1932; U. S.Bureau of Animal Industry, unpublished data; and Dmson, Phillips, and Speelman,1945. the same, and in some of the groups was quite small, cautionmust be used in drawing definite conclusions, particularly with regard to small deviations in the growth curves. For example, the apparent increases in weight found in the fifth winter for the Belgian and Morgan maleswere due to the averages being increased by the loss of the smallest animals in thosegroups, rather than to other factors.

The weights of the horses after three years of age were notas representative of true weights as those before that time, as many of themares were pregnant part of the year and some horses were worked or ridden, and given extra feed while performing such work. Growth of the horses in height shows the adverse effects of inadequate feeding in winter periods (Fig. 54), but not to thesame extent as growth in weight. Height is largely a skeletal measurement and would show little, ifany, loss during periods of insufficient feed.

112 65 PERCHERON dd+ (---GRADE DRAFTdd (COLUMBIA. ) (MILEScal%MONT / 64 - /-* .,GRADE DRAFT gy 63 ---0 (MILES CITY, MONT )- -a- - 62 ------(MIDDLEBURY, VT.) - 0---- */-MORGAN cfc3`

61 ( ',Allis CITY,MONTI-

60 -0*--MORGAN 99 - - (MIDDLEBURY. VT.) (n59 Li -X4-MORGAN 99 C)58 (MILES CITY, NONT)__

57 o 56 Li 55

24 30 35 42 48 54 60 128 AGE (MoNTHS) Figure 56. Growth in height of range-fed horses vs. growth in height of horses fed liberally under farm conditions. Data are from Trowbridge and Chittenden, 1932; U. S. Bureau of Animal Industry, unpublished data; and Dawson, Phillips, and Speelman, 1945.

In most of the groups the males tended to be taller and heavier than the females and to mature a little more slowly, as shown by their growth curves, which do not flatten out as quickly as those of females. However, on the basis of increases in height and weight, and under the feeding and management conditions in this work, there does not appear to be any evidence that the draft horses matured more rapidly than the light horses, as had sometimes been claimed (Gay, 1932; Harper, 1913). There was a definite tendency for the method of management used in these experiments to produce horses that matured, as judged by their size at 5 years, somewhat below the size to be expected had they been fed adequately during all stages of the growing period. This is indicated by comparison with data obtained on groups of draft colts fed at Columbia, Missouri (Trowbridge and Chittenden, 1932) and at Ithaca, New York (Harper, 1921). While these colts were at first smaller than those at Miles City, they finished at about the same size (Figs. 55 and 56). Comparisons with Crampton's (1923) data on 409

113 TABLE 25.COMPARISON OF GROWTH OF HORSES U N DER RA N GE AND OTHER CONDITIONS. Animals Weights in Kilograms at different ages

Weanling 1.yr. 11/2 yrs. 2 yrs. 3 yrs. 4 yrs. Miles City draft colts (avg. four groups) 274.5 436.4 493.6 476.8 544.5 639.1 Crampton's colts 331.8 463.6 613.6 672.7 1813.6 1900.0 Relative weights of Miles City colts, in percent of weights of Crampton's colts 83 94 80 71 67 71

1 Stallions predominated intheseclasses.

American-bred draft colts furnished similar evidence. Although his colts were larger than the Miles City draft colts, the latter did not maintain the same relative rate of gain or mature at as large a proportion of their yearling weight, as is shown in Figure 55 and Table 25. On the basis of Crampton's (1923a) statement that a draft colt receiving proper feed and care should have attained at one year of age 50 percent of his mature weight, the Miles City draft horses should have weighed about twice their yearling weight at maturity, or over 815 kilos (about 1,800 pounds), instead of about 680 kilos (1500 pounds). The growth curves for weights and heights of the Morgan horses' at thc U. S. Morgan Horse Farm at Middlebury, Vermont, were much more uniform than those at Miles City (Figs. 55 and 56). This was because the stock at Middlebury received adequate rations for growth the year round. The Mor- gan males at Miles City grew at practically the same rate as those at Middlebury, except that their growth fluctuated much more between summer and winter. The mares at Miles City, on the other hand, grew more slowly, and matured,as judged by their size at 5 years, at approximately 45 kilos (about 100 pounds) lighter weight and at 3.8 cm. (1.5 inches) less height than those at Middlebury.

Adaptability in Swine

Most experimental work with swine has been conducted inareas where good supplies of concentrated feeds are available and where conditions might be considered optimum or near optimum for pork production. Very little attention has been given to the problem of producing swine under generally unfavorable environmental conditions.

1 Unpublished data, U. S. Bureau of Animal Industry.

114 The only extensive studies having a bearing on this problemwere conducted in China. They were designed to compare several native types with each other, to compare these native types with modern purebred swine and with crosses between various modern purebreds and the native Chinese swine. Many questions remain unanswered concerning the relative adaptability or suitability of various breeds and crosses to conditions under which Chinese swine are generally raised. However, the resultsare of sufficient interest to justify rather extensive treatment here, since they not only contain useful information but indicate the vast amount of work that is necessary if even preliminary solutions to such breeding problems are to be found. Chinese swine may be divided roughly into two main classes, the North- Ch ina and South-China types. North-China hogs are long, lean animals with long narrow heads, rather straight faces, and large ears. Black is the predominating color and white markings are rarely seen. The back is narrow and usually isstraight or slightly sagging. The hams are very light. Wrinkles on the face are usually parallel and run with the long axis of the face. The rate of growth is relatively slow, but sows are reported to be quite prolific. South-China pigs are shorter, broader backed, and more rotund. The hams are somewhat larger, but not as plump as those found on most American and English breeds. The back usually sags more than in North-China pigs. The head is short and rather wide, the face somewhat dished. Wrinkles on the face may be tortuous and tend to run at right angles to the long axis of the face. There is considerable variation in color in different regions ranging from solid black to nearly white, and with some red or reddish brown. The sows are reported to be less prolific than those of the North- China type, and the pigs grow more rapidly, but there is considerable variation among the South-China pigs. The hair is somewhat softer than on the North- China pigs. The hogs of North China may be divided into two classes, a large and a small type. There are graduations between these two extremes, and medium is also sometimes used in describing them. Black strains predominate in many regions of South China, but black-and- white strains, such as the Yungchang and Cantonese, are typical of certain localities. Yungchang hogs are found principally in Yungchang lisien (county) and parts of Lungchang and Luchow hsiens to the south and west of Yung- chang. These hogs are white over most of the body and have black spots around the eyes, varying from narrow circles to large spots that include much of the

115 head and ears. They are sometimes referred to as "bi-spectacled whites." Some entirely white or nearly all white animals are seen. Adjacent to the home of the Yungchang hog there is a region where many black-and-white hogs are found, owing to crossing of the Yungchang with black strains. Cantonese hogs are found in the vicinity of that city and adjacent regions. The predominating color is black-and-white, with considerable variation in the relative amounts of the two colors. These hogs have been described by Levine (1920), who states that colors range from nearly white to black, or black with white points. In some localities the ears are large and pendulous, ii others they are small and erect, though both types are sometimes found in the same community. There is considerable evidence to indicate that this is the area from which most animals were exported from China for use in early swine breeding in Great Britain. Black hogs predominate in most other regions of South China, though some black and white pigs are found in Chekiang, Kwangsi, and Hunan provinces, and animals with white markings are seen occasionally in other areas. Many of those in Chekiang have a tendency toward white belting- white with black over the head and rear quarters. The natives refer to these as "two-ends-black pigs." Red or reddish-brown animals are frequently seen among the black strains, especially in the mountainous regions of Kweichow, Szechwan, and Sikong and similar regions to the north and south. There is considerable variation in type within the black strains, even in adjacentareas. For example, the hogs around Neichiang, Szechwan province,are larger, less chuffy, and somewhat later maturing than those around Chengtu in the same province. Hogs in the mountainous regions tend to be somewhat leaner in appearance than those of the more fertile lowlandareas, but they may reflect differences in environment rather than in heredity. The work reviewed below was conducted at National Central University, and was largely financed by a grant from the Rockefeller Foundation incon- nection with its rural reconstruction program in China. From February 1936 to October 1937 the work was conducted at Nanking. After the Japanese invasion, the staff and part of the herd were moved to Chungking and then to Chengtu. After the move to Chengtu, the Szechwan provincial government co-operated with the National Central University in the work until it was concluded in 1941.

Because of wartime conditions some details of the datawere lost. The work is inadequate in some respects, and notas complete as could be desired in others. Nevertheless, these appear to be the only data of their kind in existence

116 and should be of considerable interest to swine breeders. Much of the information has been published in Chinese, by Hsu and his associates, but asum- marization of data and conclusions was given by Phillips and Hsu (1944) to make the findings generally available to workers who cannot utilize the criginal material. The Chinese swine used at Nanking were of the North-China type, with the exception of a few from Chekiang that were intermediate, while those at Chengtu were of the South-China type. Rations used at Nanking were comparable to those commonly fed under conditions of good management in the United States, but tankage was not available at Chengtu so only vege- table protein was supplied. A survey of levels of fertility on farms in four sections of Szechwan, including the Chengtu, Yungchang, and Neichiang areas, revealed that litter size varied from 8.4 to 9.1 in the four areas and averaged 8.8. In 31 sows native to the Chiangpei area of Kiangsu, an average litter size of 13.9 was observed. Tong (1943) cites an exceptional case of a North-China black sow, kept at Minghsien College, that had 32 teats and produced 25 live pigs in one litter. Levine (1920) says that in the Canton area a sow is supposed to be able to nurse at least 10 pigs, which seems to be the average for the region, though as many as 15 are frequently seen with one sow. It appears that the Cantonese sows are more prolific than those in some other parts of South China. Chinese pigs are reputed to develop sexually more rapidly than modern breeds. Chinese animal-husbandry workers cite instances of gilts being bred, by litter-mate boars before 60 days of age. Gilts are usually bred when about five months old, but earlier breedings are common and Chinese workers say that it is not unusual to find gilts farrowing at about six months of age. This is in marked contrast to the findings of Phillips and Zeller (1943) with the Poland China breed in the United States in which spermatozoa were first observed in the testes at 20 weeks of age, and large- and small-type gilts exhibited first estrus at 198.7 and 207.8 days, respectively. Hsu and Peng (1942) studied 10 gilts of the type found in the vicinity of Neichiang, Szechwan. Five were on a standard and five on a typical farm ration; the average ages of first estrus were 88.6 and 108 days, respectively. First estruF averaged 5.2 and 5.8 days in length and later estrous periods were shorter, the average for the groups varying between 2.0 and 3.0 days, after the second estrus. These gilts were checked for estrus twice daily. Pigs from Chiangpei in Kiangsu province and Chinhua in Chekiang were compared and both types were about equal in rate of growth. The Chinhua

117 pigs had more subcutaneous and less kidney fat than those from Chiangpei. Chinhua pigs are produced on the borderline between the North- and South- China types and, owing to the thicker back fat, appear to be more like the South-China type than those of Chiangpei. The black and white markings indicate that they may be intermediate between the North-China and a black- and-white strain of the South-China type. Relatively few data are available on the feedlot performance of native pigs. Some of the data given by Phillips and Hsu(1944),which indicate relative performance of native Chinese types, are summarized here. Data are also supplied showing relative growth rates and other characteristics of Chinese swine and crosses between Chinese and modern swine. A comparison of the performance of three strains of Szechwan pigs by Hsu and Chiang(1940)showed that the types differed in time of fattening and in weight when it was most profitable to market them. Small black pigs from Chengtu were at their optimum condition at90Kg. (180 catties,1 larger black pigs from Neichiang at 125 Kg. (250 catties) and Yungchang pigs at 105 Kg. (210 catties). At lower weights they were not fat enough to please the public demand for a fat carcass, and if fed longer the gains became too expensive. Some data obtained on animals being slaughtered in the normal course of business in the Chengtu, Neichiang, and Yungchang markets are criven in Table 26.

Hsu and Peng(1941)studied the performance of six sows and their progeny from the Neichiang (Szechwan) and eight from the Yungchang (Szechwan) area (see Table 27). The pigs were weaned at 10 weeks and put on feed at 13 weeks of age. Average- or medium-size pigs in each litter were selected for feeding, the extra-large or small ones being discarded. The number of pigs farrowed is much higher than that cited as theaverage for farm sows of this type, but these sows were especially selected andwere maintained under much better conditions than are commonly foundon farms. The Neichiang pigs grew at a more rapid rateover the entire feeding period, but the greatest difference occurred after they reached 110 Kg. (220 catties). The same pigs made more efficient gains; the difference of 33.8 Kg.(67.6 catties) in feed required for 50 Kg. (100 catties) gainwas statistically significant. The carcasses of the Yungchang pigs were somewhat fatter, owingto slower growth and a longer fattening period.

1- This is the new catty, equal to 1/2 kiloor about 1.1 lb. The old catty was equal to about 1.3 lbs.

118 TABLE 26.SUMMARY OF SLAUGHTER DATA IN THREE SZECHWAN MARKETS. Items Chengtu Neichiang Yungchang compared March AprilMay Winter Spring Winter Spring No. of hogs 19 35 30 37 35 28 16 Live weight (Kg.) 84.9 90.8 86.6 118.9 136.2 110.5 98.1 Dressing percent 72.2 66.1 68.2 78.7 79.0 75.4 72.4 Caul fat (percent) 1.79 1.71 1.92 4.80 5.20 4.73 4.09 Kidney fat (percent) 2.84 2.78 3.05 5.02 5.27 5.33 4.23 Back fat (cm.) 5.73 5.67 5.55 6.87 7.51 8.13 7.65 Length of bristles (cm.)1 9.11 8.81 8.04 12.39 11.29 13.44 11.79 1 Bristles on back.

Levine (1920) reports that 12 hogs fed at the Canton Christian College made an average daily gain, at six months of age, of about 0.29 Kg. (0.65pound) a day on full feed, and that these pigs usually weigh between 90 and 114 Kg. (200 and 250 pounds) at one year. The average dressing percent of 32 hogs was 72.5. The studies in which native pigs were compared with modern and modern X native crossbreds are treated below. Because different native types were used at Nanking and Chengtu, the work at the two locations is reviewed sep- arately. The modern breeds involved at Nanking were Berkshire, Chester White, Duroc Jersey, Hampshire, and Large Yorkshire. The Duroc Jersey and York- shire hogs were rather large and rangy, while the hogs of the other four breeds were of a smaller, more compact type. Nativepigs were of the North-China type and came from the vicinity of Chiangpei, Kiangsu.Numbers were limited

TABLE 27.AVERAGE PERFORMANCE OF 6 NEICHIANG AND 8 YUNGCHANG SOWS AND THEIR PROGENY.1 Items Breeding of sows and pigs compared Neichiang Yungchang Pigs farrowed 12.7 12.0 Pigs weaned 10.3 8.5 Avg. birth weights (Kilograms) 0.75 0.75 Avg. weaning weight (Kilograms) 13.0 12.3 Avg. initial weight in feedlot (Kg.) 15.5 13.9 Avg. final weight (Kilograms) 121.9 120.1 Avg. final age (days) 331.3 387.0 Avg. daily gain (Kilograms) 0.45 0.36 Feed in catties per 100 catties gain2 506.7 574.3 1 Four pigs per litter were fed. 2 This is the new catty, equal to kilo or about 1.1 lb.

119 and the modern breeds were grouped together for some comparisons with the native pigs. Loss of original records because of the war makes it impossible to indicate the proportions of the various modern breeds in some of these cases. All pigs were given comparable treatment, and the management and feeding were as near to generally accepted American standards as working conditions would permit. The ration generally used included corn, tankage, soybean oil meal, bone meal, and salt. In feeding trials with fattening hogs, the protein content of the ration ranged from about 16.6 percent at the beginning to about 12.9 percent at the end. The duration of gestation was similar in all groups. The average length of 32 gestations in modern sows was 115.8 ± 0.51 days; in 21 gestations in native sows it was 115.1 ± 0.39; and in five Fi sows mated to modern boars, it averaged 113.6 ± 0.87. Pigs from sows of modern breeds were somewhat heavier than those from native sows at birth. The average weight of 334 pigs of modern breeds was 1.03 ± 0.02 Kg. (2.06 ± 0.04 catties). Eighty-eight native pigs averaged 0.81 ± 0.02 Kg. (1.61 ± 0.04 catties) and 314 crossbred pigs out of native sows average 0.85 ± 0.01 Kg. (1.69 ± 0.03 catties). Differences between various groups are shown below, with their standard errors: Modern vs. Native 0.23 ± 0.029 Kg. (0.45 ± 0.057 catties) Modern vs. F1 0.18 ± 0.025 Kg. (0.36 ± 0.049 catties) F, vs. Native 0.04 ± 0.025 Kg. (0.08 ± 0.049 catties)

The native sows were smaller and had larger litters than the modernsows, which at least partially accounts for their pigs being lighter. The 462 male pigs born in this work averaged 0.93 Kg. (1.86 catties) and the 346 female pigs 0.92 Kg. (1.84 catties) at birth; the differencewas not significant. The sex ratio was 1335. The Chinesesows are reputed to be good mothers and the available data bear out this belief. Data on survival to weaning (at 10 weeks of age)are given in Table 28.

Weight loss of the sows owing to reproduction isgreater in the native sows. Sixteen modern sows averaged 158.5 Kg. (317 catties) before parturition. They lost an average of 20.4 Kg. (40.8 catties) during parturition, and19.2 Kg. (38.4 catties) during 10-weeks lactation,a total of 39.6 Kg. (79.2 catties). Eighteen native sows averaged 142.9 Kg. (285.7 catties) before parturition, lost 23.6 and 23.0 Kg. (47.1 and 46.0 catties), respectively,at parturition and during lactation, or a total of 46.6 Kg. (93.1 catties).

120 TABLE 28.COMPARISON OF LITTER SIZE IN MODERN AND NORTH-CHINA NATIVE SOWS. Type Number of pigs of No. of PercentNo. weaned sows litters Born End 1st wk. Weanedweaned per litter Modern 26 262 201 179 68.3 6.88 Native 22 307 259 236 76.9 10.73

The Chinese sows, being smaller, consumed less feed than the modernsows during lactation. During 1936 the average daily feed consumption of four sows of each type was 4.97 and 6.1 Kg. (9.93 and 12.1 catties) per head. During 1937 the sows had access to green alfalfa and the consumption of concentrates was somewhat lower, averaging 4.42 Kg. (8.84 catties) daily for 12 modern sows and 3.87 Kg. (7.73 catties) for 11 native sows. An interesting comparison was made of the combined feed consumption of the sows and their pigs during the nursing period (see Table 29). The difference in efficiency of production, thus measured, was 47.5 ± 10.65 Kg. (94.9 ± 21.29 catties). The native sows were raising hybrid pigs, however; there is no direct comparison of the modern and native types. Data on performance of various breeds and crosses during the feeding period are given in Tables 30, 31, and 32. Ca cass data on some of these groups are provided in Tables 31 and 32. The growth rate of native pigs was slower than that of either the modern purebred or the modern X Chinese groups that were fed. Native pigs required about 281 days from birth, on the average, to reach market weight (about 90 Kg. or 180 catties)., while crossbred pigs (sired by modern boars, and out of native sows) required about 208 days, or 73 days less to reach the same weight. Differences in efficiency of feed utilization are not nearly so marked. In the groups for which data are shown in Table 31, the two native lots required the largest amounts of feed per unit gain, but in the groups treated in Table 32, the two native groups fall within the range of the crossbred groups.

TABLE 29.COMPARISON OF FEED UTILIZATION DURING LACTATION IN MODERN AND NORTH-CHINA NATIVE SOWS AND THEIR LITTERS. Type of No. of Gain per litter Feed per 100 catties gain 1 sows litters (Kilograms) (in catties) Modern 16 116.7 417.2 ±18.67 Native 15 138.7 322.3 ±10.22 1 This is the new catty, equal to Vz kilo or about 1.1 lb.

121 TABLE 30. PERFORMANCE OF MODERN PUREBRED AND MODERN X NATIVE NORTH-CHINA CROSSES, 1936 DATA' compared Items Hamp-shire Berk-shire Berk-shire Hamp- shire X Breeding and sex of pigs Hamp- shire X Berk-shire X Berk-shire X PolandChina X PolandChina X York-shire X s.) Initial weight (kilograms) f emale 16.7 barrow 21.7 f emale 19.7 barrownative 16.8 femalenative 16.7 barrownative 21.6 f emalenative 21.5 barrownative 16.2 f emalenative 14.0 barrownative 16.8 Av.Days daily on feed gain (kg. ) . . . 140 0.50 112 0.62 126 0.56 112 0.68 154 0.48 112 0.61 112 0.58 140 0.54 154 0.51 112 0.63 Feed (in catties) per 100catties gain'2 ThisI Pig§ is werethe new put catty.on feed equal at 13 to weeks, ,X kilo or or 3 about weeks 1 after.1 lb. weaning. Four pigs per lot. 390:6 360.1 381.6 341.9 401.2 382.0 374.7 399.0 394 6 338.4 TABLE 31. PERFORMANCE OF MODERN PUREBRED, NATIVE, AND MODERN X NATIVE Items CROSSES, 1937 DATA' Breeding and sex of pigs Hampshire Yorkshire Yorkshire Chester Whit Initial weight compared Hampshire barrow Hampshire female Hampshire female barrowNative femalespayedNative PolandfemaleChina X barrownative X femalenative X barrow and f emalenative X FinalDays onweight feed (kilograms)(kilograms) 139 21.090.0 133 22.793.7 133 22.487.4 220 10.388.7 268 87.6 8.3 123 91.616.4 134 90.419.7 130 93.219.6 117 28.490.7 FeedAv. daily (in catties) gain per 100(kilograms) catties gain 3. 455.5 0.49 462.5 0.47 459.2 0.49 484.6 0.36 540.3 0.29 403.3 0.61 415.2 0.53 352.8 0.57 465.6 0.54 LengthDressingNo. slaughtered of (percent)2 small . intestine (meters) 21.772.3 4 17.971.8 3 20.370.9 4 17.172.4 2 14.274.5 4 18.874.0 4 71.818.3 4 18.269.5 4 76.917.7 4 KidneyCaul fat fat (percent)(percent)2 2 1.731.75 2.072.00 1.571.87 3.943.75 4.535.54 1.941.68 2.422.45 2.141.92 2.402.43 Back fat (cm.)4. . 2PercentiFour pigs of per live litter weight. were put on feed at 13 weeks or 3 weeks after weaning . 5.12 .7 This is the new catty, equal to 3 5.20 4.10 4.65 kilo or about 1.1 lb. 4.99 5.12 4At top of shoulder. 6.00 5.83 5.88 TABLE 32. PERFORMANCE OF NATIVE AND MODERN X NATIVE CROSSBREDS' compared Items Hampshire X Berkshire native X Breeding of pigs Berkshire native X Yorkshire native X Duroc Jersey native X Duroc Jersey native X DaysInitial on weight feed (kilograms) . . Native192 10.5 Native188 15.4 115native20.7 122 21.2 126 21.1 120 19.1 9426.6 126 20.2 Av.Final daily weight gain (kilograms) (kilograms) . . . 89.8 .39 87.4 .39 90.2 0.61 88.9 0.56 89.3 0.54 89.8 0.59 90.0 0.68 91.6 0.57 FeedDressingNo. (in slaughtered catties) (percent)2 per 100 catties gain3 395.2 71.1 6 374.9 4._ 384.6 77.1 8 396.1 74.9 8 396.8 74.4 7 364.6 72.4 7 359 . 9 72.2 8 360.34_ CaulLength fat of (percent)2 small intestine (meters) 15.7 3.49 18.5 3.26 16.6 2.75 16.4 2.48 18.1 2.12 22.3 2.702.67 BackKidney fat fat (cm.) (percent)2 native lots only. 1Pigs were weaned at 10 weeks and put on feed at 13 weeks 2Percent of live weight. 3.754,55 - 3 This is the new catty, equal to 3.146.75Eight pigs per lot. 6.263.24 Barrows and giltskilo are or aboutincluded 1.1 inlb. all lots. 7.502.76 6.212.20 4Data lost in evacuation of Nanking. 4.40 Females were spayed in the TABLE 33.AVERAGE DRESSING PERCENTAGESOF VARIOUS GROUPS OF HOGS'

Dressing per cent and Breeding of pigs No. of pigs standard error

Hampshire 12 72.7 ± 1.04 Berkshire 7 78.8 ± 0.25 Native (Chiangpei) 42 73.3 ± 0.43 Native (Chinhua)' 6 72.1 ± 0.58 Hampshire X native 15 76.9 ± 0.51 Berkshire X native 20 75.1 ± 0.76 Chester White X native.. 4 77.1 ± 0.19 Yorkshire X native 18 72.5 ± 0.60 Duroc Jersey X native 8 72.1 ± 0.76 Poland China X native... 7 76.1 ± 0.60

1I3ased on warm carcass weight. '2Butehered at lighter weights than other groups.

The dressing percentages available for various groups, includingsome animals in addition to those listed in previous tables, are given in Table 33. The native groups fall within the range of the purebreds and crossbreds. Some definite differences appear in the mode of fat deposit. The data for caul and kidney fats are summarized in Table 34. All the differences listed in the lower half of this table are significant; they indicate that the native pigs put on relatively more caul and kidney fat than the modern breeds, while the crossbreds are intermediate in this respect. The few pigs studied from Chinhua, Chekiang, were similartothe crossbreds,caulfataveraging 2.44 ± 0.37 Kg. (4.88 ± 0.73 catties) and kidney fat 2.55 ± 0.34 Kg. (5.10 ± 0.70 catties), but they were slaughtered at somewhat lighter weights than the other animals; at equal weight they would have been nearer to the other native pigs. Back fat was significantly thicker in native and crossbred pigs than in the modern group, but the crossbred and native pigs did not differ significantly (see Table 35). The few Chinhua, Chekiang, pigsused, which were slaughtered at somewhat lighter weights, had a thickness of back fat of 5.66 ± 0.32 cm., or nearly as thick as that of the crossbreds and Chiangpei. Kiangsu, natives.

125 TABLE 34.SUMMAR-Y OF DATA ON CAUL AD KIDNEY FAT IN CARCASSES FROM VARIOUS GROUPS

Average and standard error Group Caul fat Kidney fat (kilograms) Modern breeds 1.53 ± 0.10 1.86 ± 0.14 Modern X native 2.33 ± 0.05 2.59 ± 0.06 Native (Chiangpei) 3.51 ± 0.21 4.32 ± 0.22

Difference between: Modern and crossbred 0.80 ± 0.11 0.74 ± 0.15 Native and crossbred 1.18 ± 0.21 1.73 ± 0.23 Modern and native 1.98 ± 0.23 2.46 ± 0.26

TABLE 35.SUMMARY OF DATA ()N THICKNESS OF BACK FAT ANI) SKIN, TAKEN AT TOP OF SHOULDER

Average and standard error Group Back fat Skin (Centimeters) Modern 4.47 ± 0.21 0.20 ± 0.003 Modern X native 5.70 ± 0.14 0.28 ± 0.011 Native 5.83 ± 0.26 0.33 ± 0.021

Difference between: Modern and crossbred 1.23 ± 0.26 0.08 ± 0.012 Native and crossbred 0.13 (not sig.)' 0.05 ± 0.024 Modern and native 1.36 (significant)1 0.13 0.021

'Actual standard error calculated but now unavailable owing to loss of records.

126 Thickness of skin was greatest in the native, lowest in themodern, and intermediate in the crossbred pigs (see Table 35). In the Chinhua, Chekiang, pigs thickness of skin was similar to the modern pigs, averaging 0.2cm. The native swine used at Chengtuwere of two types, the rather large black pigs found in the vicinity of Neichiang, Szechwan, and the "bi- spectacled" white pigs typical of the Yungchang, Szechwan,area. The rations used in feeding trials were balanced accordingto the same standard used at Nanking, but tankage was not available and all the proteinwas of plant origin. Berkshire, Chester White, Yorkshire, and Poland China boarswere used to sire crossbred pigs, and their performance recordswere kept (see Table 36). All the crossbred groups grew ata more rapid rate and their gains were somewhat more efficient. No material differences appear between the natives and the crossbreds in length of the small intestine and in deposition of fat, the native litters falling between the extremes observed in crossbreds in most of these measures. The only exceptions were caul and kidney fat, in which the Yungchang native pigs showed the highest levels ofany. Bristles have long been an important source of income to Chinese swine producers. It is not possible to predict the future importance of bristles; much depends on developments in synthetics. Native Chinese hogs have longer and stiffer bristles than the modern hogs of the United States, with which they were compared, and the methods 6f management result in a much longer period for bristle growth before the hogs are slaughtered. Before the war, white bristles were more valued than black and the Yungchang hogs were a chief source of white bristles. Data on bristle length at the end of the feeding period were obtained (see Table 36), but they are inconclusive because of small numbers. Crossbreds' bristles compared favorably and in one case exceeded those of the native animals in length. However, bristles on the crossbreds were not as stiff as those on the natives. In the various feeding trials summarized above, the animals were maintained under experiment-station conditions, with management and feeding practices as comparable with those used in the United States as the circumstances permitted. In Szechwan, where this work was done, the pigs are normally weaned at from one to two months of age and the majority of them are sold to poor farmers who feed them scantily for two to five months, then resell them as medium-sized feeders. These are handled by small tenant farmers and others who feed them mostly roughage and farm refuse, and use them as a means of providing manure for their land. They sell the hogs as large feeders to well-to-do farmers and to proprietors of mills, oil presses, breweries,

127 TABLE 36. PERFORMANCE OF NEICHIANG AND YUNGCHANG NATIVE PIGS, AND CROSSES WITH MODERN BREEDS1 compared Items Yungchang Neichiang Berkshire X Berkshire X Breeds of pigs Yorkshire X Yorkshire X Chester White X Poland China X Initial weight (kilograms) . . native 16.7 native15.2 Yungchang 14.7 Neichiang 18.6 Yungchang 15.3 Neichiang 18.0 Yungchang 14.3 Neichiang 15.6 FinalDays onweight feed (kilograms) . . . 224 91.8 230 93.6 181 90.8 186 91.6 161 91.6 202 90.4 179 91.1 171 91.2 FeedAv. daily (in catties) gain (kilograms) per 100catties gain' . . 487.0 0.34 524.5 0.29 448.8 0.41 420.2 0.39 438.4 0.48 474.2 0.36 449.6 0.43 425.2 0.44 DressingNo.Length slaughtered of (percent) bristles (cm)3. . . . 65.9 3.245 61.8 33.04 64.3 43.38 67.6 42.82 73.2 54.61 64.8 52.85 64.8 3.035 65.1 53.40 CaulLength fat small (percent) intestine(meters) . 20.7 2.46 21.5 1.96 21.3 1.01 20.1 2.05 19.8 2.08 18.2 2.14 21.8 1.76 22.2 1.47 BackKidney fat (cm.) fat (percent) 'Five pigp per litter were used. 5.122.94 2.425.93 2Catty = 3z 6.352.08 kilo or about 1 11h. 4.05,2.39 4.882.74 3 Bristles over withers. 5.422.10 7.281.75 6.501.97 TABLE 37. GROWTH OF PUREBRED, NATIVE AND CROSSBRED PIGSUNDER NATIVE FARM CONDITIONS

Number Average initial Average final Breeding of pigs At At Age beginning end (days) Weight Age Weight (kilograms) (kilograms)

Native 4 1 100 15.0 380 93.0 Native 3 2 120 20.5 288 43.0 Berkshire 4 2 100 13.5 352 35.3 Berkshire 2 2 160 20.3 384 50.3 Hampshire 4 3 100 12.9 380 59.7

Large Yorkshire... . 7 4 154 20.8 348 64.3 Chester White X native 4 2 120 15.5 288 64.5 Duroc Jersey X native 4 3 100 17.3 380 100.9

etc., to be fed on fattening rations for two or three months, after which they go to market as slaughter hogs. The total feeding period, from weaning to slaughter, may vary from six months to two years. There are many variations, but this is the essential pattern of swine production in Szechwan. The animals are "stretched up" largely on roughage and under otherwise poor conditions of environment, after which they are fattened for a brief period on relatively good-quality feeds. Available experimental evidence (McMeekan, 1938) indicates that this procedure tends to produce animals with relatively underdeveloped muscles and a high proportion of fat. A limited test was made of the performance of some native, modern purebred, and crossbred pigs under experiment-station conditions until they weighed from approximately 15to 29 Kg.(Ioo to 150 days). They were then distributed to farmers to be fed in their own way. Weights were taken at intervals of four weeks, until the pigs were approximately one year old (see Table 37). Obviously, the numbers are too limited for definite conclusions. The data do not indicate definite superiority of any of the three general groups. Much further work is required to determine the adaptability to Chinese farm conditions of the modern breeds and crosses between these and native types.

129 The data obtained in all these experiments, even though quite detailed, are sufficient to permit only tentative conclusions: Chinese native hogs become sexually mature at an earlier age than modern American and English hogs. North-China sows appear to be more prolific than modern sows and most South-China sows. Chinese native sows appear to be somewhat better mothers, as judged by the percentage of pigs weaned. Sows of the North-China type wean a greater total weight per litter than modern sows, owing to larger initial litter size and better survival. Individually, modern and modern X native crossbreds gain much more rapidly than native pigs, during both the nursing and fattening periods, and reach a larger mature size. Data on efficiency of feed utilization give some indication that native animals tend to be less efficient than the modern and modern X native crossbreds, but in sotne trials no difference was apparent. Native Chinese hogs, especially those of North China, tend to store up more internal fat during the fattening period than modern and modern X native crossbreds. At comparable weights the North-China native hogs also had a thicker layer of back fat than the modern breeds, while crossbredswere intermediate. Direct comparisons were not made between modern and South- China native types, but crossbreds exceeded the native pigs in thickness of back fat in some cases. Chinese swine usually produce stiffer, longer bristles than modern breeds. The environment under which the Chinese hog is born and raised is less favorable than that usually provided in the United States and Great Britain, where the modern breeds with which theywere compared originated. Information is not yet sufficiently complete to indicate how well modern and modern X native pigs can compete with native pigs under Chinese farmcon- ditions. Swine in most parts of the worldare used primarily as converters of concentrates into meat for human consumption. They also utilize some roughage, the amount varying from small quantities of chopped legume hay mixed with concentrates to a nearly complete ration of roughage such as is consumed by the growing pig (between weaning and thé beginning of the fatteningperiod) in China or the pigs that mustrange for a living in the Himalayan highlan.ds (Fig. 57). It seems probable,on the basis of field observations, that hogs

130 vary widely in their ability to utilize roughage, but experimental evidence that would enable us to measure such variations is almost entirely lacking.

Hogs are maintained under a wide variety of environmental conditions,ranging from the Corn Belt of the central United States, where conditionsare near ideal for pork production, to the plains of northern India, where animals must withstand high summer temperatures (Fig. 58), and the piney-woods section of southern United States and the highlands of Tibet, where animals must forage for their own feed for most of their lives. In many intermediate areas where pork production is developed to a high degree, producers depend to a considerable extent on imported feeds, and may have inadequate supplies of concentrates. Under such conditions, the ability to utilize pasture and other roughage effectively is obviously an important characteristic of swine. It is evident that if swine are to play an important part in an agricultural economy, particularly in areas where temperature, supply of concentrated feeds, and other factors place limitations on their production, attention should be directed to the breeding of types adapted to such conditions.

Figure 57. Hogs of a type found in limited numbers in the upland areas of Sikong Province, China. They exiSt largely on grass and other roughage. Photo by Ray G. Johnson.

131 a r .11Noras

Figure 58. Entrance to a hog-house in a Central India village. This tunnel-like arrangement leads to a small underground compartment where hogs can escape the intense summer heat of the plains of India.

132 V

USE OF LE?)S-KNOWN TYPES OF ANIMALS 1,11VESTOCK PRODUCTION

It is quite natural that types of animals such as domestic cattle, horses, sheep, and swine, which have proved suitable for use in the major livestock- producing areas of the world, should have received muchmore attention in programs designed to improve their productivity than yaks, water buffaloes, camels, and other types that have been used in many less-developedareas. The native environments of these latter types are, in many cases, quite rigorous. The animals that have survived and served man for centuries under such conditions obviously are well adapted to their environment. In planning the improvement of livestock production in these areas, it is important that native types of livestock be given adequate consideration, to ensure that misguided attempts to replace them with less suitable types be avoided, and to encourage responsible authorities to undertake programs designed to increase the productivity of the native types. No attempt will be made in this chapter to give complete descriptions of the less-known native animals and their special adaptabilities -and- abilities to produce and work under difficult conditions. The object is,rather, to call attention to some of the more important types and indicate their general usefulness, with the hope that these comments may help to stimulate interest in their improvement.

Water Buffa loes There are no authentic records to show when the domestication of water buffaloes began, but there is little doubt that most of the present-day domestic breeds originated from the wild water buffaloes of India. It is not difficult to see similarities between the present-day domesticated buffalo in India, those in the rest of Asia, and their wild prototype (Bos ami) in the Assam jungles. The latter has a massive forehead with thick-based flat horns and a chunky, massive, low-set frame. There is also a certain amount of similarity between the domesticated Jaffarbadi breed of water buffaloes from Kathiawar, India, and the wild Cape buffalo of Africa (B. cager) which has a short, thick, convex forehead with massive, thick-based horns which usually have a downward curly sweep.

33 FigL water buffalo of one of the milking types found in India.

There is also some historical evidence that domestic buffaloes from India, later known as water buffaloes or riverain buffaloes because of their affinity to water ponds or reservoirs, were introduced into Italy sometime in the 6th century, and into Egypt before that. They were found in the Philippines when the islands were first visited by Spaniards. Other distributions with their epicenter in India were eastwards to China, Burma, Siam, Malaya, Java, Suma- tra, Borneo, Philippines, and also westwards to Southwest Asia, Africa, spread- ing far up the Nile, and to the countries of southern Europe. Buffaloes of what appear to be the Jaffarbadi variety have also been introduced into Trinidad, where they are used by Hindu immigrants as draft animals. Itis estimated from census figures of reporting countries that the total world population of water buffaloes is approximately 78 million. India alone contributes approximately 48 million, China ranks next, and there are sizable numbers in all the countries of Southeast Asia.In addition to these and other Southeast Asia countries, the following countries report buffaloes as part of their livestock population: Bulgaria, Egypt, Greece, Hungary, Iraq, Rumania, Syria, arid Turkey. In conformation the buffalo is rather heavy, appears low-set because of its great depth of body, and usually has dark pigmentation throughout, except

134 under the root of the tail, where it is usually light. The skin isglossy and smooth with very coarse hair. The hideappears tough and lacks a perspiring mechanisrn except at the muzzle. Formation of the head and hornsvaries according to types. The tail usually is notas long as in cattle and the switch is small, with very little tuft. Height varies accordingto the breed between 118 and 160 cm. (46 and 62 inches) at withers and the lengthas measured from shoulder point to pin bones varies between 128 and 154cms. (50 and 60 inches). Weights of mature females vary frona 360 to 680 kg. (800to 1,500 pounds) according to breed, while bulls weighing between 725 and 900 kg. (1,600 and 2,000 pounds) are not uncommon.

As far as the formation of forehead goes, there are two distincttypes. One is the Jaffarbadi, which shows close similarity toB. eagerof Africa and has a distinct convexity of forehead, the bulge occasionallyso prominent that the eyes look sunken. The other type, which includes many breeds, has much less convexity and the backward slope of the forehead is much gentler. In both types, the horns are thick at the base and angular rather than round. The Jaffarbadi type usually has a bend which goes intoa curve, while in the latter the horns usually have a sweep backwards, though at different angles, giving an appearance of flatness. This type has more similarity toB. al-72i. In the low humid rice-growing tracts of China, Siam, Indo-China, Malaya, Philippines, Sumatra, and India, the buffalo has been extensively used for paddy cultivation. Because of itsslow movement and considerable draft ability, the animal is peculiarly suited to this form of cultivation. Buffaloes have tremendous power to pì1i. 1vy loads but on highways they are comparatively slow. They usually move at the rate of about 3 Km. (2 miles) per hour with a load of about 900 to 1360 Kg. (1 to11/2tons). In Oriental forest areas they are used to move large logs. Castrated males are docile and easy to handle. In India, Egypt, Iraq, Syria, and some of the southern European countries the water buffalo is used for milk production (Fig. 59). Milk is used either for direct consumption or for manufacturing such products as cream, butter, cheese, yogurt,ghee(clarified butter), khotva (desiccated milk), etc. Unfortun- ately, there is not one milk-recording organization or society for buffaloes in any part of the world today. However, some information may be surmised from bits of available data. Water buffaloes in Egypt and some of the southern European countries are reported fo yield as much as 900 to 1360 Kg. (2,000 to 3,000 pounds) of milk in a lactation period of 8 to 9 months. Records from India show that some of the developed breeds, such as Murrhas, produce

135 TABLE 38.SUMMAR,Y OF ANALYSES OF COMPOSITION OF MILK FROM WATER BUFFALOES. Solids Calculated calories Country Water Fat not fat per lb.' (percent) India 83.46 7.05 9.49 496 calories Italy 82.16 7.99 9.85 543 Egypt 82.24 7.96 9.80 542 China 76.80 12.60 10.60 778 Philippines 78.25 10.35 11.40 663

1 On the basis that1 lb. of 4 percent milk=340 calories. between 1360 and 2270 Kg. (3,000 and 5,000 pounds) of milk during a lactation period of 9 to 10 months. Occasionally animals are seen that produce up to 4545 Kg. (10,000 pounds) of milk, with a daily production in peak period of 25 to 27 Kg. (55 to 60 pounds) in two milkings. This shows the economic potentiality of this species as a milk producer. In India the water buffalo is largely used as a dairy animal. It is estimated that total production of buffalo milk in India is in the neighborhood of 11 million metric tons per annum. This figure is equivalent to about 16.3 million metric tons of cow's milk, if the caloric value of buffalo milk is taken into consideration. Buffalo milk is always white, never markedly yellow even with high carotene feeding. Analyses of buffalo milk are not as extensive as those of cows' milk, but the reported analyses summarized in Table 38 give a fair indication of its composition. The meat of the water buffalo is coarse-grained, rather watery, and lacks interfibrial fat (marbling), which adds so much to the palatability of meats. Beef production from the water buffalo has not been a major enterprise inany part of the worldusually only worn-out work animals and discarded dairy animals are used for meat. This side of water-buffalo husbandry -requires fuither study. Hides of water buffaloes are thick and tough. They are valued by the tanning industry for the manufacture of leather.

Compared to cattle, buffaloes are slow-maturing, even under favorablecon- ditions of good feeding and judicious management. From records maintained in India, it seems that on an average the age at first calvingmay be 31/2 to 4 years. Careful records regarding estrous cycles are not available, but it has been observed that duration of estrus in buffaloes may be anywhere from 6 to 48 hours, depending upon individuality andseason; the estrous cycleis18 to 28 days in length. Buffaloes show a strong tendency to be seasonal breeders.

136 In practicallyallthe countries calving takes place between August and Ociober. The period of gestation is 308 to 318 days. As a rule, the water buffaloes are huge feeders and less discriminating than cattle in foraging. This makes them suitable for exploitation of thecoarse natural pastures and other forages of the tropics. Because of the absence of an efficient perspiring mechanism the buffalo is likely to suffer from hot temperatures. To counteract the effects of heat, they are allowed to wallow in ponds or water reservoirs or are splashed with water. Some interesting work has been done by Minett (1947) and Sinha and Minett (1947) on the effects of application of water to the body surface of buffaloes and its effect on body temperature and milk yield. This work was conducted in India where the water buffalo is an important milk producer. It was found that a heavy artificial shower for two hours would lower the body temperature by 2.8° F. in the morning and 1.6? F. in the afternoon, on the average. In observations on wallowing it was found that adult water buffaloes wallowed naturally from April to October when air and water temperatures were above 85° and 77° F. respectively. A desire to wallow was most intense from July to October. In comparing the various methods of cooling water buffaloes it was found that wallowing for 20 minutes and one hour gave

Figure 60. A water buffalo of the type used primarily for work in the rice fields of China.

137 similar results. Hosing for three minutes was as effective as wallowing for 20 minutes, while splashing water from buckets for 10 minutes was not quite as good as- the other two techniques. It was concluded, that in organized dairies cooling by showers or hosing should be most effective, more hygienic, and no more costly than a well-constructed wallow. Observations on the effect of cooling on milk production were made on 15 milk buffaloes during the optimal period of their lactation. It was shown that during the h.ot months wetting of the bodies of buffaloes is essential. When this was not practiced as a routine the milk yield decreased and became more irregular. The water buffalo has amply demonstrated its value in the tropicsas a milk producer and as a draft animal, particularly in the rice fields (Fig. 60). It is, therefore, worthy of much more attention than it has so far received byagen- cies interested in livestock improvement.

Yaks Yaks are indigenous to the mountainous regions of central Asia. The'vare of great value to man in these regions, being well suited to travel over rough

Figure 61. A yak cow being milked bya Tibetan woman in Chinghai Province, China.

138 terrain and well adapted to grazing at high elevations on steep slopes. Cross- ing with cattle, they produce the hybrid pien nitt, which are used extensively by Mongolians and Tibetans. Yaks are used for carrying wood and supplies by private individuals and for packing in commercial transportation. In addition to their use as beasts of burden, they produce milk (Fig. 61), thus providing a staple food in the high-plateau regions. They furnish meat, their hides are used for leather, their hair is used for making rope and the thread used in weaving tents. For the most part, yaks are grazed in the vicinity of the villages in winter, or near the nomad tents in summer. No supplemental feed is given during the season when grass is obtainable, and no hay is put aside for winter use. In periods of heavy snowfall, especially during the later winter and early spring, losses are frequently heavy; their resistance is low and the animals cannot survive m4ny days without feed. In such periods, choice animals are sometimes fed dried casein or other food to keep them alive. In many areas, the ranges are overstocked. There is urgent need for better range management. The more enterprising owners allow their animals to graze both day and night. In areas where it is unsafe to allow the animals to graze untended at night, a guard is posted over them. Some owners allow grazing only during the day and tie up the animals at night. New-born calves may be housed in the yak-hair tents, or in yurts, during the night, for safety and to reserve the morning milk for human use. More con- siderate milkmaids may leave a little for the calves. Suckling calves follow their dams during the day unless the weather is too stormy. At night the milk not taken by the calf is obtained for human use. In some areas animals are milked only once daily, usually in the morning. Concentrates are seldom fed to calves. Some whey left from the making of casein or milk residue is occasionallyfe'cl. Calves learn to eat grass when quite young. During the summer months, when grass is growing, the calves make fair growth, but during other portions of the year, and especially during the late winter and spring months, there is not enough feed to permit normal growth. These periods of near-starvation stunt the young stock and weaken mature animals. Losses are heavy. It is especially difficult for the calves and yearlings to survive the winter, but less-adapted types would be unlikely to survive at all. Packsaddles used on yaks are of the same design as those used for horses and cattle, consisting of a felt pad and a wooden framework to which the load is tied. Loads are removed at the end of the day or trip, but the saddle is frequently left on for days at a time, apparently to avoid the difficulties of

139 saddling the animals each morning, but sometimes to protect the animals from storms. Saddle sores are frequent. Most yaks and their products are used by the people that produce them. Some animals are sold for use in pack caravans, but there is little organized marketing. In some areas of the grasslands, markets are held at certain seasons in connection with religious festivals. Milk is used for drinking and for production of butter and milk residue or casein. Some of these products go to the lamaseries and some is stored for winter use. Relatively little is sold. Butter for marketing may be packed in sheep or goat stomachs. Hair is collected as it falls out or when the animals are shorn during the summer. Yields are said to be about 0.5 to 0.7 Kg. ( 1 to 1.5 pounds) per animal, but no actual data are available. The hair is used for making tents, felt, ropes, and other things. The coarse hair is used for the twine from which tents, grain bags, and similar articles are woven; the finer undercoat is used for felt making. Tail hairs are collected and used to make dusters. Some hides arc sold for leather, but the tanning and processing of leather is generally poorly done. In Sikong, China, for example, a considerable portion of the hides are used in the raw state to wrap tea, butter, and salt for transport. The material is wrapped with the wet hide, which deteriorates in transit until it cannot be used againa very wasteful procedure. The yak is well adapted to high altitudes and does not appear to be adversely affected by cold weather and snow. It is seldom found at low altitudes and does not stand up well in hot weather. The animal is adept at ranging for feed on the mountains. When turned loose it goes to the higher elevations to feed, at times above 5180 m. (17,000 ft.) altitude. It grazes comfortably in places where cattle and horses could find footing only with great difficulty. The yak can also dig through snow for feed. When grass is extremely scarce, and cattle and horses cannot long survive, yaks eke out an existence by licking up broken and wilted blades of last year's grass that have been blown by the wind and partially imbedded in the soil. Under such conditions yaks may spend eight hours a day licking up dead grass to keep them alive and working. Small wonder that pack trains often move only 13 to 16 Km. (8 to 10 miles) a day. More details about the yak and its place in the economy of peoples living on the high plateau and mountainous regions of central Asia are given in publications by Phillips, Johnson, and Moyer (1945) and Phillips, Tolstoy, and John son (1946). Soine information concerning their possibleuse in parts of Alaska is provided by White, Phillips, and Elting (1946). It is evident that

140 these animals are particularly suited to the use of pastoral peoples who liveat high altitudes. Little attention has been given to improving their productivity, or to utilizing them in areas other than their native habitat. It seems likely that, by the application of modern breeding methods, their usefulness in central Asia could be materially impro-ved. It is also possible that they could serve a useful purpose in other parts of the world where similar environmental conditions prevail.

Reindeer

Reindeer are used extensively in the far northern portions of Asia, Europe, and North America. Their use in North America is relatively recent, dating from importations of 1,280 animals into Alaska from Siberia in 1891 and 1902. By 1934 the herds in Alaska contained approximately one million animals. This rapid expansion indicates that they served a useful purpose in a new region where conditions were similar to those in their native home. A detailed description of the reindeer industry in Alaska is given by Palmer (1934). The reindeer is used for many purposes. It serves to some extent as a beast of burden, for packing in summer and for drawing sleds in winter (Fig. 62). It can readily be broken to halter and to pulling a sled. The average animal can carry 27 to 32 Kg. (60 to 70 pounds) on its back, pull a sled weighing 45 to 135 Kg. (100 to 300 pounds), depending on trail conditions, and can cover 32 to 40 Km. (20 to 25 miles) a day. Its most important products are meat (Fig. 63) and hides. Reindeer leather is used by Laplanders and other northern peoples for boots, parkas, mittens, socks, leggings, trousers, and sleeping bags, and in commerce it provides fine leather for kid gloves and leather jackets. Meat, including the heart, liver, and tongue, is used for human food. Some is jerked and smoked, some is canned, at least in Alaska. Antlers, bones, blood, and viscera are used in the preparation of meals fed to dogs and foxes; some antlers are used for the manufacture of knife handles and handcraft products. In some countries, reindeer milk is used for making cheese and butter. The reindeer was domesticated and developed from the wild caribou of northern Europe and Asia. Palmer says that average animals in Alaska stand 108 to 113 cm. (42 to 44 inches) high at the shoulder and measure 1.7 to 1.8 m. (51/2 to 6 feet) from nose to tip of tail. The dressed carcass weighs about 68 Kg. (150 pounds), with exceptional carcasses weighing as much as 91 Kg. (200 pounds). The live weight of 3-year-old males ranges from 118 to 136 Kg.

141 Figure 62. Reindeer hauling cannp supplies on sleds in Alaska. Photo by W. B. Miller, U. S. Fish and Wildlife Service.

(260 to 300 pounds), and females of the same age are about 36 Kg. (80 pounds) lighter on the average. A variety of range types can be utilized by reindeer. In Alaska, for example, they are grazed on dry and wet tundra and on interior mountain areas. The forage includes lichens, shrubs. sedges, vveeds, grasses, mosses, willows; alders, birches, and some other kinds of plants. Reindeer can be grazed on open range throughout the year (Fig. 64), and in Alaska, for example, no cultivated forage is fed even in winter. Palmer (1934) says that the suitability of range for reindeer depends principally upon climate and forage, and to some extent upon topography. Since the natural habitat of these animals is in the Arctic and subarctic regions, they will undoubtedly do best on ranges within these climatic zones. Whether they can be grazed successfully farther south is not

Figure 63. Reindeer steers in good condition for slaughter. Photo by W. B. Miller, U. S. Fish and Wildlife Service.

142 definitely known. The area- selected for grazing should lend itself to efficient herd management throughout the year. It should comprise a natural grazing unit, including spring, summer, fall, and winter ranges. In heavily forested country, reindeer are difficult to herd successfully unless the grazing areas are fenced. On winter grazing in Alaska, Palmer points out that in the Arctic region the range selected must include an area not subject to periodic crusting of snow. Because of winter rains, even within the Arctic Circle, certain areas near the coast are subject to crusting. Under such conditions herds may suffer great losses through starva.tion, for the animals cannot paw through hard crust for food. When a crust forms, the herd must be moved back promptly to pro'tectedareas in the interior hills. Under ordinary conditions the depth of snow- in coastal winter ranges does not seriously affect grazing, since at least part of the area is generally exposed to winds and does not become deeply covered. In the interior, however, particularly in timbered fiats and benchland

Figure 64.Reindeer grazing on open range in Alaska. Photo by L. J. Palmer, U. S. Fish and Wildlife Service.

143 Figure 65. A large bull camel of a type considered desirable in North China. Photo by Ray G. Johnson.

country, there is less drifting and the depth of snow affects the selection of winter range. Where there is much drifting, certain areasmay become so deeply covered that the animals cannot reach the vegetation. Ordinarily,to uncover lichen forage, they will paw through 0.6 m. (2 feet) of packed snow and 0.9 to 1.2 m. (3 to4feet) of loose snow. It is evident that reindeer are peculiarly adaptedto conditions in the Far North, and efforts to improve them foruse under those conditions should be encouraged.

144 Camels and Dromedaries The two-humped camel is found primarily in central Asia and the one- humped dromedary lives mostly in southwestern Asia and northern Africa. In both areas as "ships of the desert," these animals are of great value to the peoples who inhabit the drier portions of Asia and Africa. The primary uses of camels and dromedaries are for transport of goods and passengers in desert and semidesert areas. Wool, milk, skins, and meat are by-products of this main function.

Accurate data on the working capacity of Chinese camels (Fig. 65)is unavailable. According to Phillips, Johnson, and Moyer (1945), who obtained their data from camel-owners in China, camels in North China travel 35 to 40 Km. a day on long trips and up to 85 Km. on short trips. The strongest camels carry 275 Kg. and cover 1,150 Km. in 30 days. Camels of average size and strength may carry about 140 kilos at the beginning of the working season, but only 120 at the end. In some areas such as Ningsia the average load is reported to be about 115 to 140 kilos. Cross (1917) gives some figures on the loads for camels in India that are interesting by way of comparison. He states that the load allowed on government camels is 182 kilos, that natives load as heavily as 270 to 360 kilos, and that the strongest camel can carry up to 435 kilos. These loads are apparently for dromedaries. Cross also states that camels can walk at the rate of 21/2 miles (about 4.1 Km.) per hour and, if at continuous work, should not be allowed to cover more than 20 to 25 Km. a day. He recommends one day of rest in each week. Cross says that a good riding camel (Fig. 66) can travel at the rate of 10 to 12 Km. (6 to 7 miles) per hour and cover up to 100 or 115 Km. in a stretch. If at continual work they can average 50 Km. a day for several days. Camels are also used in some areas for pulling wagons. Camel hair or wool is used for making blankets, certain clothing materials, and other textiles. Young camels have fine hair of good quality but that of old animals is relatively poor. The price in northwest China was reported by Chang (1941) to be three times that of sheep wool. The average yield is said to be about 2.4 kilos, but large animals yield asmuch as 3.5 kilos. The production of camel wool in Manchuria was reported (Wang, 1942) to be 32,463.2 Kg. (71,419 pounds) in 1937. The estimated number of camels was 12,800. If these figures are accurate, the yield per head was about 2.5 Kg. (5.6 pounds). Camels are seldom shorn, because shearing results in a too-sudden change and some animals become ill. Shedding begins in April and is complete by about the end of May. The wool falls out in bunches and is picked up, or it may be pulled out as it loosens.

145 The camel has received very tittle attention in attempts to improve livestock, and many animal husbandmen consider it a beast possessed of little beauty and of an obstreperous disposition. However, it serves a highly useful purpose in arid and semiarid regions where other means of transport are not apt to replace it generally in the immediate future. Some attention to its improvement is certainly justified.

Llamas and Alpacas The llama and alpaca are members of the camel family. They and their wild relatives (the huanaco or guanaco and the vicuna) are found chiefly in the mountainous Pacific-coast regions of western South America.

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146 The llama (Figs. 67 and 68) stands 1.2to 1.4 m. (4 to 41/2 feet) high at the shoulders and weighs about 114 Kg. (250 pounds)on the average. It carries burdens weighing up to 57 Kg. (125 pounds) and is ableto cover 19 to 24 Km. (12 to 15 miles) a day. It is generally patient and docile, anditE great usefulness as a pack animal has earned it the sobriquet "ship ofthe Andes." The ability of these animals to thrive and workat high altitudes makes them particularly valuable in the Andes. Schmidt (1945)reports that few llamas are seen below 3660 m. (12,000 feet) and few alpacas below 4270 m. (14,000 feet) in Peru. The meat of the llama is notvery palatable, and the hair is inferior to that of the alpaca, though itis used for similar purposes. The llama, therefore, has its greatest usefulness as a pack animal. Available data indicate that there are approximately 2,000,000 llamas in Bolivia, somewhat less than 1,000,000 in Peru, and about 100,000 distributed through the higher areas of Ecuador, Chile, and Argentina. The alpaca (Fig. 69) is maintained primarily for its hairor wool and is kept in large flocks, particularly by Indian tribes in the high mountains of Peru. Somewhat snialler than the llama, it seldom measures more than 1.1m. (31/4 feet) at the shoulders. These flocks graze in the high valleys, almostat the snow line. They do not, as a rule, go to lands below 1830 m. (6,000 feet). They are gregarious and have instinctive habits of vigilance. Once every two years the alpaca herds are driven to enclosures and sheared. The average clip is reported by one writer to be about 1.6 Kg. (31/2 pounds) per animal. The annual growth of the hair or wool is reported to be about 20 cm. (8 inches), but is subject to much variation. Longer fibers are obtained when the shearing is done in alternate years, and fleeces with fibers of 0.6 m. (2 feet) ormore are seen. It appears possible to produce fibers of the lengths réquired for commercial purposes by adjusting the time of shearing. The fibers are small, but strong and elastic, and range from black to gray or yellowish in color. They are very lustrous and silky, and are valued for weaving fine, warm cloth. In general, the fleeces of the llama and alpaca are similar in character to those of the Angora goat. The hairs are quite uniform in diameter and length. A high percentage of kemp is present in fleeces of llamas, whereas the fine alpaca fleece has practically none. The raw fiber contains a small amount of natural grease (less than 4 percent), and the total amount of impurities usually does not exceed 25 percent. The average yield of clean fiber is 80 percent. In addition to the production of wool, the alpaca serves to a limited extent as a beast of burden and its flesh is used as human food. Alpaca skins are used for clothing and rugs.

147

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Figure 68. Llamas in Peru with Ilamero in attendance. Photo by courtesy of Pan American Union.

The alpaca population in Peru is estimated at more than 1,500,000, that o f Bolivia about 200,000, with undetermined numbers in Ecuador and northern Chile. In most cases, the herds are owned by native tribesmen and graze in a semiwild state for long periods. Llamas and alpacas can be crossed. The offspring are known as huarizo (Fig. 70). Obviously all of these an;mals have a fundamental place in the economic life of the peoples of the higher Andes. One of their wild relatives, the vicuna (Fig. 71), is also of some importance since it has an unusually fine soft coat. It is commonly found in small herds at about 4880 m. (16,000 feet) elevation and has not been domesticated, though some attempts are being made in this direction. It is smaller than the llama and alpaca, and in color ranges from a

Figure 67. A pair of prize-winning llamas and their owners, Morococha, Peru. Photo by Ewing Gallotvay, provided by courtesy of Pan American Union.

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deep fawn to a golden chestnut, shading off to a pallid white beneath the body and on the surface of the extremities. Most vicunas are found in Peru. Matthews (1947) reports that the Peru- vian Government is enforcing a law of 1921 aimed at their protection. Peru, according to Matthews, is now taking an annual census of the various flocks. According to figures released by the Peruvian Departm'e` nt of Agriculture, the number of vicunas in Peru at present is approximately 1,000,000. With adequate enforcement of the law and even stricter hunting and breedingregu- lations, the flocks may continue to increase. The available supply of vicuna fleeces at presentisvery small, approximately 1360 Kg. (3,000 pounds), altogether. This commodity is sold exclusively under license from the Peruvian Government.

150 igure 71. Vicunas native to the highlands of Peru. Photo by courtesy of Fred F. McKenzie. VI METHODF OF BREELV

Methods of breeding that can be applied in underdeveloped areas of the world fall into three categories: Selection within the native types; Grading-up with already improved types or breeds from other countries; and Development of new types out of animals that are graded only part of the way up to the improved type. It must be recognized, before improvement programs are begun in underdeveloped areas, that some of the existing types are meeting the needs of the people reasonably well. Others may need improvement in some or most of their economically important characteristics. Granting that improvement may be needed, it must be recognized further that adaptability to environment is especially important in these areas and should not be overlooked. Selection within a native type has certain advantages. The native types are already adapted to the local environment, which may not be true of types brought in from other countries, and there is no problem of selection and importation of foreign stock. The disadvantage is that progress is much slower than grading-up with already improved types, provided the improved types meet local needs and are adapted to the environment. Grading-up has the obvious advantage of rapid improvement through the use of improved males on large numbers of native females. It isthe logical method in all cases where there are existing types in other countries that meet a country's needs and which are apt to perform satisfactorily under the conditions in question. If this method proves satisfactory, foreign breeds or other improved herds need be maintained only as sources of males to continue the grading-up program, while the bulk of animals in the area or country would become high-grades as the program progressed. In many casesit may be found that imported purebred animals cannot perform satisfactorily under existing environmental conditions. Grades with a certain amount of improved breeding may withstand the environment satisfactorily and produce at higher levels than the native stock. In such cases, the obvious procedure is to determine the extent to which improved breeding can be introduced, then develop a new type from animals with this breeding background.

153 The three practical methods outlinedindicate the means of approach that are available under conditions where little if any improvement of native stock, has been accomplished. There are breeding problems under the most favorable environmental conditions that man can provide for his animals, and grading-up also has its place there. While a discussion of breeding for such favored conditions is outside the scope of this publication, an understanding of the basic tools breeders can use under such circumstances is essential also to those who plan breeding programs under less favorable circumstances. The three basic tools the breeder has to bring about genetic improvement in his aniinals are selection, inbreeding, and crossing. These tools have been used to develop existing breeds, they will be used to effect further improvements, to establish new types and breeds, and to raise the productivity of commercial livestock. Beyond them, the breeder uses a knowledge of the physiology of reproduction to insure maximum fertility and maximum opportunity for selection.

Selection

The breeder's abilitytoselect superior animals as parents of the next generation is one of the most important factors that determine progress in animal breeding. If the breeder is to select genetically superior animals, he must have yardsticks to measure superiority. And if he is to utilize effectively in selection the knowledge he obtains through application of these yardsticks, he must know which selection procedures will result in greatest progress. Several recent studies have yielded important information on these points.

A breeder may use one of three basic methods of selection: First, the "tandem" method, in which he selects for one character at a time until it is improved, then selects for another, and so on, until all desired traits are improved; ,second, the "total score" method, in which selection for all desired traits is practiced simultaneously, the total score or index being constructed by adding into one figure the superiority or inferiority for each trait considered; third, the "independent culling levels" method, in which he sets a certain level of merit for each trait, and discards all individuals below that level, regardless of their rating in other traits.

A careful investigation of the efficiency of the three methods of selection was made by Hazel and Lush (1942). From their study of the theories involved, they conclude that selection for a total score or index of net desirability is more efficient than selection on the basis ofindependent culling levels, and that the tandem method is the least efficient of the three.

154 Although selection on the basis of independent culling levels isegenerally less efficient than selection for totalscore, it does permit earlier selection for some traits, without waiting for other traits for which selection can best be made at later ages. The superiority of the independent culling levelover the tandem method increases with the number of traits involved and the intensity of culling. Hazel (1943) also studied the principles of constructing and using selection indexes, or the "total score" method of selection. The genetic gain, he observes, that can be made within a group of animals by selecting for several traits at once is the product of the selection differential,or intensity of selec- tionthe superiority of selected animals over theaverage of the entire group- th.e multiple correlation (a measure of relationship) betweenaggregate breeding value and the selection index, and genetic variability. The selection differential is limited by the rate of reproduction of each species, and itmay be small because of the breeder's carelessness in making selectionsor in emphasizing unimportant points. Genetic variabilityisrelatively beyond man's control. Hence, the greatest opportunity for increasing progress from selection is by ensuring that the multiple correlation is as large as possible. Hazel gives a multiple-correlation method of constructing indexes having maximum accuracy. These are its constants: Relative economic values for the different traits. Standard deviations (measures of variation) for each trait. Correlations (measures of relationship) between each pair of traits. Heritability of each trait (a measure of the extent to which expression of trait is governed by heredity). Genetic correlations between each pair of traits. The genetic correlations show the extent to which traits are similar because of genes that affect both traits, and are determined by correlating one trait in one animal with the other in a relative. Using these principles, Hazel developed three indexes for swine. The first involved two characters for which data were avagable before breeding 'age. The index (I) was: I=(0.137 x W)(0.268 x S) in which W is the pig's weight at 180 days and S the pig's market score. The second index was: I=(0.136 x W)(0.232 x S)+(0.164 x P) in which W and S are the same as in the first formula and P is the productivity of the dam, used as a measure of the pig's productivity, the lapse of one genera-

155 tion being compensated for by a suitable adjustment for the heritability of this trait. The third index was designed to include information about the average weight (W) and score (S) of the litter in which each pig was born, in addition to the three traits in the second index. These were considered as fourth and fifth variables, using the correlations between the various traits and making allowances for the number of pigs per litter, when arriving at the values to insert in the index. The three indexes were compared to determine their relative efficiency in rnaking genetic progress. Rate of progress is proportionate to the size of the correlation between genotypes of the selected animals and their indexes. The second and third indexes were 8.8 and 11.3 percent, respectively, more efficient than the first. Since the time and effort expended in keeping records is but a small fraction of the total labor 'connected with a breeding program, the second index would probably be preferable to the first in most cases. The third might also be chosen over the second, since genetic progress could be increased a little more through its use, and the extra labor would be only that of com- puting and using the litter averages from data already available. The progress that could be made by using the three indexes studied by Hazel was 36.3, 39.5, and 40.4 percent, respectively, of that which could have been made by a perfect index, or one in which the phenotype, or appearance of the animal, was a perfect measure of the genotype, or genetic make-up, of the animal. The loss is due to the confusing effects of environment; dominance of one gene over its pair-mate, so that the recessive member of the pair is not evident in the phenotype; and epistasis, or interaction of genes, all of which can make phenotypes unlike genotypes. A selection index for Rambouillet sheep has been developed at the United States Western Sheep Breeding Laboratory at Dubois, Idaho, based on the same principles as those outlined for swine. These traits have been included: face covering (F), length of staple (L), weaning weight (W), typescore (T), condition score (C), and neck-fold score (N). The completed index (1) is as follows: 1=-75(15 x F) + (7 x L) W + (0.4 x T) (7 x C) (11 x N) The constant of 75 is added to ensure that the index will be positive and average around 100. Corrections for various factors, like twinning, age of dam, and inbreeding, may be made directly on the index, using suitable correction constants. The completed index varies from about 70 to 150 for individual lambs in the Rambouillet flock at Dubois, with an average of about 110. The

156 value of the index may be estimated by comparing theprogress when the index was used with that before itwas available. Progress was roughtly determined by combining the selection differentials for the various traitsafter each was weighted by its heritability and its economic importance. Over-all progress from selection at weaning age was increased in the range of 20 to 50 percent by the use of the index.

The breeding merit of an animalmay be estimated in various ways, including the merits of its ancestors, the animal'sown characteristics and performance, the merit of collateral relatives, such as sibs (brothers and/or sisters) and half sibs, and the merit of its offspring.

The last is usually called the progeny test. Much has been writtenconcern- ing its accuracy, compared to that of other methods that might give indirect measures of breeding merit. From the standpoint of rate of genetic progress, factors other than relative accuracy must be considered. The most important of these factors are the age at which progeny tests may be obtained and the rate of reproduction. The longer interval between generations that results from use of the progeny test tends to offset the advantage gained by more accurate selection, and may actually reduce the annual rate of improvement. The relative merits 'of progeny testing and other methods of selection have been studied by Dickerson and Hazel (1944). This is an intricate problem requiring detailed mathematical studies in Order to obtain a solution. They considered a number of traits in various species, and concluded that the possibilities of increasing progress by a regular plan for use of progeny--tested sires are limited to certain kinds of livestock and to certain traits. Their reasons are outlined here: The less the interval between generations is increased by progbny testing, the more likely it is that progeny testing will increase progress. This is illustrated by an example contrasting the results of selecting for weanling and yearling traits in sheep. Use of the best ram tested the year before on an optimum portion (60 to 70 percent) of the ewes increased progress by about 4 percent for weaning traits, but reduced it for yearling traits, as compared with progress to be expected from use of only the two best yearling rams each year. The only difference between these two examples is that one year is required to obtain progeny-test information on weanling traits, while two years are required for yearling traits. When the rate of reproduction is low, progeny testing of sires is more likely to increase progress. The resulting increase in genetic superiority of parents tends to be lafger, relative to the increase in age of parents, when

157 there is less opportunity for early culling, particularly among females. For example, progeny testing affects progress more favorably for yearling traits in sheep than for growth rate in swine. Obviously, a much higher proportion of the female offspring must be retained in order to maintain the population in sheep than in swine. 3. If the basis for making early selections is relatively inaccurate, the progeny test is more likely to be effective. Therefore, the progeny test would be more apt to improve the annual progress in traits where heritability is low than in traits where it is high. Thus, the relative value of the progeny test is determined by a combination of circumstances that are largely beyond the breeder's control, and a regular plan of progeny testing is unlikely to increase (and may reduce) genetic progress unless the progeny-test information becomes available early in the animal's lifetime, the reproductive rate is low, and the basis for making early selections is relatively inaccurate. Dickerson and Hazel point out that improvement from selectionis nearly maximum for most traits when culling is based on individual performance, family average, and pedigree, and when the interval between generations is kept short. Dickerson and Hazel also studied the effectiveness of different methods of selecting for two specific characters in swine, growth ratc of pigs and productivity of sows, and they have made some recommendations concerning the procedures that should be most effective. In selecting for growth rate, they recommend that 8 to 10 times as many boars and about 3 timesas many gilts as are needed for breeding should be retained long enough after weaning (such as 180 days of age) to obtaina more reliable measure of growth rate than weaning weight. The rest may be culled without reducing appreciably the effectiveness of selection. Several plans for culling were compared. Yearlyprogress from selection is greatest when sows are culled after the first litter, the best one-thirdto one;half being kept for a second litter 6 months later. Another plan, which is ahnost as effective, is to delay culling until after the second litter, and keep the best one-fifth to one-fourth of thesows for a third litter at 2 years of age. Progress is retarded by retainingmore than the optimum proportion of older sows, because the less intense culling of sows and the longer interval between generations is only partly offset by themore severe culling of gilts and the greater accuracy of sow culling. Having sows farroW fwo littersa year results in more rapid genetic improvement in productivity, since it permits the accuracy of selection of boars and gilts to be improved by basing the dam's productivityon two litters instead

158 of one. It also permits themore productive sows to be kept for additional litters, with a minimum increase in theaverage interval between generations. It is important that the breeder have efLctive yardsticksof merit, regardless of the selection procedures and breedingsystem he uses. Evaluation of the fitted animal in the show ring haslong been considered an important part of livestock improvement inmany countries. In recent years it has become increasingly apparent that this procedure hasmany shortcomings as a tool for selection of improved breeding stock.For obvious reasons, only a small portion of the animals raised each generationcan be prepared for evaluation. The condition of the animalsat the time of the show is usually highly artificial, and quite often isvery different from the condition that idesired in practice. Undue attention is often givento so-called fine points of little or no economic importance. Some traits, suchas milk yield and efficiency of feed utilization, cannot be accurately evaluated by visual inspection. The practice of excessive fitting has been carriedover to the conditioning of breeding stock for sale, and is found to a marked degree, for example, 'even in bulls and rams that are to be sold for use on westernranges in the United States. Thus the breeder spends an undue amount for feed to put excessive faton the animals, for which the buyer must pay, but for which he has nouse. Also, the excessive fat may obscure defects in conformation, a point that is aptly stated in the common phrase, "Fat is a pretty color." Recognizing the need for improved yardsticks, many workers are seeking to develop measures of the economically important characters. Some characters, like litter size in swine, May be observed directly. Others, like body size, rate of growth, milk yield, yield of grease wool, and length of staple, can be weighed or measured directly. Others, for example face covering, skin folds, and body conformation in sheep, require indirect methods of evaluation and the assignment of a score to represent the degree of development in each animal. Devices have been developed for measuring such characters as length of wool fibers, tenderness of meat (muscle), diameter of wool fibers, density of wool fibers, and hardness of fat. Much attention also has been given to measuring functional traits, such as efficiency of feed utilization in beef cattle and swine, physiological response of horses and mules to exercise, and performance of work by draft horses and mules and by light horses in carriage and under saddle. Many of the developments are still in the experimental stage, but active research is continuing at many institutions to test existing procedures, to develop new ones, and to simplify experimental procedures so they can be applied by breeders in evaluating and selecting their stock.

159 Before leaving the problems of selection, further note should be taken of the limitations placed on progress through selection by the relatively low heritability of most economically important traits in livestock. The heritability of a trait is actually a measure of the observed variation in a group of animals that is caused by differences in heredity. Estimates of heritability are based on the degree that related animals resemble each other more than less closely related or unrelated animals. These estimates are appli- cable primarily to characters or traits in which development depends upon many genes. Considerable information has accumulated in recent years on the heritability of various characters in livestock. The information helps the breeder because it indicates the progress that can be made by selection and the plan of breeding that is likely to be most effective. Practically all the information on heritability of economically important traits in livestock has been obtained during the last decade. A summary of most of this information was prepared by the author (Phillips, 1943-47) and is reproduced in Tables 39 to 44. Variations occur, of course, and many apparent discrepancies, in the estimates of heritability. There are several reasons for this. Errors may be made in sampling, particularly in studies based on small numbers of animals, so the results are not representative. Variations in environment may be correlated for certain kinds of relatives. For 'example, data may have been collectedover a period of years that fail to reflect gradual changes in feed or management. Both the dams and their- progeny, raised at various times during this period, may have been exposed to an environment better or poorer than the average. Such environmental contributions to likenesses between relativesare difficult to measure. Another factor that may affect estimates of heritability is the mating system. A different 4proach is required to obtain a reasonably accurate estimate of heritability in an inbred population than in one where random mating has been practiced, a factor that has not been taken into account .insome of the studies. In others, the mating systemor the amount of inbreeding may have deviated more (or less) from random than the investigator supposed. An example from the data on heritability of weights of swineat various ages serves to illustrate the usefulness of such information. Data on weights and growth rates in Tables 39 and 40 indicate that the estimates of heritability increase as pigs grow older. Therefore, selection for maximum weight should be most effective if practiced at 180 days, rather thanat earlier ages. Herita- bility of weight at 180 days approximates 30 percent. Thismeans the breeder should expect to make about 30 percent of the progress he "reaches for" in

160 TABLE 39.ESTIMATES OF HERITABILITY FOR WEIGHTSOF SWINE Al VARIOUS AGES

Age Herita- Method used to determine (days) bility heritability Reference

(percent) 16 Paternal half sib Lush et al. (1934) do Baker et al. (1943) Birth. .. O do Nordskog et al. (1944) 4.6 do Krider et al. (1946) 14 Intrasire regression Nordskog et al. (1944) 4 Paternal half sib Baker et al. (1943) 21 o do Nordskog et al. (1944) 24 do Krider et al. (1946) O Intrasire regression Nordskog et al. (1944)

O do Comstock et al. (1942) 56 15 Paternal half sib Baker et al. (1943) O do Nordskog et al. (1944) 13.6 do Krider et al. (1946) 7 do Bywaters (1937) 60 15 Intrasire regression Do. 18 Combination of different methods Do. f26 Paternal half sib Baker et al. (1943) 84 lo do Nordskog et al. (1944) 28 112 f do Baker et al. (1943) 1 O do Nordskog et al. (1944) 19 do 140 Baker et al. (1943) 21 do Nordskog et al. (1944)

16 Line difference due to 150 selection Krider et al. (1946) 13 7 Paternal haIf sib Do.

25 do Baker et al. (1943) 168 27 do Nordskog et al. (1944)

1 14 Intrasire regression Comstock et al. (1942) 20 Paternal half sib Whatley (1942) 62 Intrasire regression Do. 30 Intrasire offspring-dam correlation Do. 40 Full sibs, not litter mates. Do. 180 30 Regression of variance to genetic relationship Do. 23 Paternal half-sib and intrasire regression Whatley and Nelson (1942) 19 Line differences due to selection Krider et al. (1946) 23 9 Paternal half sib Do.

161 TABLE 40.ESTIMATES OF HERITABILITY FOR GAIN AND RATE OF GAIN IN SWINE

Period Herita- Method used to determine (days) bility heritability Reference (percent) Birth-21.... 7 Paternal half sib Baker et al. (1943) Birth-56.... 15 do Hazel et al. (1943)

( 0 do Nordskog et al. (1944) 21-56 -{ 15 do Baker et al. (1943) O Intrasire regression Nordskog et al (1944)

{ 17.7 Paternal half sib Nordskog et al. (1944) 56-84 20 do Baker et al. (1943) 6 Intrasire regression Nordskog et al. (1944)

{ 25.8 Paternal half sib Do. 84-112 31 do Baker et al. (1943) 10 Intrasire regression Nordskog et al. (1944) {27.8 Paternal half sib Do. 112-140 4 do Baker et al. (1943) 10 Intrasire regression Nordskog et al. (1944)

{ 24.5 Paternal half sib Do. 140-168 13 do Baker et al. (1943) 10 Intrasire regression Nordskog et al. (1944) 56-112 f28.1 Paternal half sib Do. 28 do Hazel et al. (1943) 56-168 45.3 do Nordskog et al. (1944) 112-168 17 do Hazel et al. (1943) 50-200 26 Intrasire regression Comstock et al. (1942) 56-200 40 Paternal half sib Nordskog et al. (1944) 1 Intrasire regression Comstock et al. (1942)

Birth-200... 21 Paternal half sib Nordskog et al. (1944) 3 Intrasire regression Do. Weaning -200 21 do Do. 24 Average of three methods. Lush (1936)

selection. For example, if he selécts for parents of the next generation animals that weigh 9.1 Kg. (20 pounds) above the average of his stock at 180 days, their offspring should be expected to weigh about 2.7 Kg. (6 pounds) more than the average of offspring from parents picked at random from the same stock. The heritability of a trait is one of the most important factors to consider in deciding upon the breeding plan that is most apt to succeed in improving that trait. If the heritability of the desired trait is high, the best method of

162 TABLE 41.ESTIMATES OF HERITABILITY FOR FERTILITY IN SWINE

Measure of Herita- Me hod used to determine Reference fertility bility heritability (percent) 17 Maternal half-sib litters...Lush and Molin (1942) 10 17 18 Estimated from published Do. 34 reports of various workers Litter size at 44 birth 13 Maternal half-sib litters....Hetzer et al. (1940) 15.6 Paternal half sib Stewart (1945) 14.8 Full sib Do. 13.6 Intrasire regression Do. 14.5 Average of three methods. Do. 17.6 Paternal half sib Do. Live pigs 8.8 Full sib Do. farrowed.. 15.8 Intrasire regression Do. 13.6 Average of three methods. Do. Litter size at 28 days.. 16 Maternal half-sib litters Hetzer et al. (1940) Litter size at 70 days . 20 do Do. Litter size at weaning... 17 do Lush and Molln (1942) breeding to bring about improvement is the mating of animals possessing greatest development of the desired trait, little use being made of information on pedigrees and relatives. If heritability is low, thebreeder is more apt to make progress if he 'uses information on pedigrees and collateral relatives and the information he gets from progeny tests. Also, if heritability is low, it is generally advisable to make relatively little use of inbreeding other than that needed to make families distinct from each other or to make full use of the progeny test. Once anirnals are selected from which to produce the next generation, the breeder must decide how they will be mated, and in so doing he may choose between some form of inbreeding and crossing.

inbreeding Inbreeding is the mating of animals that are more closely related to each other than the average relationship within the population concerned. Such matings tend to make the offspring more homozygous, on the average, than if their parents were of average relationship to each other. Genes occur in pairs.

163 TABLE 42.ESTIMATES OF HERITABILITY FOR OTHER CHARACTERS IN SWINE

Character Herita- Method used to Reference bilitydetermine heritability (percent) Weaning weight of Maternal half-sib litterl 18 litters Lush and Molln (1942) Productivity index of sow 16 Intrasire regression.. Hazel, quoted by Lush and Molln (1942)

Economy of gain.. . 18 Average of 3 methods Lush (1936) Body length 54 do Do. Yield of export bacon. 20 do Do. Thickness of belly... 46 do Do. Thickness of back fat. 47 do Do. Market score at slaughter 33 Average of 2 methods Whatley and Nelson (1942) Conformation score 20 Intrasire regression. .Stonaker and Lush (1942) Type score (within

strains) 38 Paternal half sib. . ..Hetzer et al. (1944) Type score (between strains) 92 do Do.

1Minimum estimate.

If both members of a pair are alike they are said to be homozygous; if they are different they are said to be heterozygous. Thus, inbreeding increases the proportion of pairs of homozygous genes, or determiners of heredity. Since inbreeding is the most powerful tool the breeder has for establishing uniform strains or families that are distinct from each other, and since much experimental work is now being conducted to determine how best to use it in livestock improvement, readers not already familiar with the technique may wish to know how the amount of inbreeding is measured. The method that is now used almost exclusively was developed by Wright (1922). This is his formula, which appears more technical than it really is: F=--[( r2) "+n ( 1 + Fa ) Fx stands for the coefficient of inbreeding of an animal, which is to be calculated. The Greek letter / (sigma) represents all the hereditary contributions to the inbreeding, but has no numeral value of its own. For example, if two or more ancestors contribute to the inbreeding, the contribution of eachis calculated and then all are added together to obtain the coefficient of inbreeding. The fraction 1/2 is the animal's relationship to each of its two parents;

164 TABLE 43.ESTIMATES OF HERITABILITY FOR VARIOUS CHARACTER:"IN BEEF CATTLE

Character Herita-Method used to determine Reference bility heritability (percent) 23 Paternal half sib Knapp and Nordskog (1946) 42 Sire-offspring regression. Do. 34 Sire-offspring regression Birth weight within year Do. 29 Paternal half sib.. . Dawson, Phillips and Black (1947) 11 Paternal half sib; corrected birth weights Do. 12 Paternal half sib Knapp and Nordskog (1946) Weaning weight.. .. Sire-offspring regression. Do. 30 Sire-offspring regression within year Do. 81 Paternal half sib Do. Final feed-1ot weight 69 Sire-offspring regression. Do. 94 Sire-offspring regression within year. Do. 99 Paternal half sib Do. Gain while on feed. 46 Sire-offspring regression. Do. 97 Sire-offspring regression within year Do. 75 Paternal half sib Do. Economy of gain . 54 Sire-offspring regression. Do. 48 Sire-offspring regression within year . Do.

53 Paternal half sib Knapp and Nordskog Score at weaning .. (1946a) O Sire-offspring regression. Do.

Slaughter grade. ... 63 Paternal half sib Do. Carcass grade 84 do Do. Dressing percent. . 1 do Do. Area of eye muscle . 69 do Do.

n stands for the number of generations between the sire and a common ancestor; n' stands for the number of generations between the dam and a common ancestor; The factor (1+F(,) represents the influence of a common ancestor, if that ancestor is itself inbred. If the common ancestor is not inbred, this part of the formula is omitted.

165 TABLE 44.ESTIMATES OF HERITABILITY FOR VARIOUS CHARACTERS IN SHEEP

Character Herita-Method used to de- Reference bility termine heritability (percent) Birth weight 30 Paternal half sib. . .Chapman and Lush (1932) Yearling staple length. 36 Intrasire regression.Terrill and Hazel (1943) Yearling weight of f38 do Do. clean wool 28 do Do. Yearling body weight. 40 do Do. Yearling body score... 12 do Do. Face covering 32 do Do. Neck folds 26 do Do. Body folds 37 do Do. Weaning weight 26.9 Paternal half sib... Hazel and Terrill (1945) 17.0 Average 3 breeds, 2 methods Hazel and Terrill (1946a) 33.9 Intrasire regression Hazel and Terrill (1945) 30 Weighted average of 2 methods Do. Staple length at 41 Paternal half sib... Do. weaning 38.7 Intrasire regression. Do. 40 Weighted average of 2 methods Do. 43.0 Average 3 breeds, 2 methods Hazel and Terrill (1946a)

15.2 Paternal half sib. .Hazel and Terrill (1946) 6.8 Intrasire regression. Do. Type score at weaning 13.0 Weighted average of 2 methods Do. 7.0 Average 3 breeds, 2 methods Hazel and Terrill (1946a)

2.4 Paternal half sib. . .Hazel and Terrill (1946) Condition score at 13.8 Intrasire regression. Do. weaning 4 Weighted average of 2 methods Do. 21.0 Average 3 breeds, 2 methods Hazel and Terrill (1946a) 45.6 Average of 4 methods Jones et al. (1946) Skin folds 51.2 Average of 4 methods, within year Do. 36.2 Paternal half sib...Terrill and Hazel (1946) 45.1 Intrasire regression. Do. Neck folds 39 Weighted average of 2 methods Do. 8 Average 3 breeds, 2 methods Hazel and Terrill (1946a) 51.0 Paternal half sib...Terrill and Hazel (1946) 60.3 Intrasire regression. Do. Face covering 56 Weighted average of 2 methods Do. 46.0 Average 3 breeds, 2 methods Hazel and Terrill (1946a) Number of nipples.... 14.4 Intrasire correlation Phillips et al. (1945) Number of functionalf26 do Do. nipples 22 Intrasire regression. Do.

166 To illustrate, supposean animal, A, has the following ancestors:

The animal has thesame grandsire (D), on both the sire's (B) and the dam's (C) sides of the pedigree. Thus D isa common ancestor of both parents of A. Since there is onlyone generation between B and D, and also one between C and D, the values forn and n' in the formula are 1 and 1, thus: Fx, (34) or( y2)3 The third power or the cube of 1/2is 1/8, which is expressed as 12.5 percent, and is the coefficient of inbreeding. This coefficient indicates the increase in the proportion of homozygous pairs of genes that can be expected,on the average, in matings where there is one common grandparent,as compared with matings where there is no common ancestor. If we suppose that random breeding has been practiced in a herd; and that 50 percent of the pairs ofgenes were homozygous and 50 percent heterozygous, then 12.5 percent inbreeding would imply that 12.5 percent of the heterozygous pairs were homozygous in the new individual (12.5 percent of 50 is 6.25)so, 56.25 percent of the pairs would be homozygous, while 43.75 percent would be heterozygous. If the common ancestor, D, in the above example had already been inbred, for example 25 percent, then the factor (1+Fa) would have been (1+0.25) or 1.25, and the inbreeding of animal A would have been 12.5 x 1.25 or 15.625, usually shortened to 15.6 percent. Inbreeding does not create or destroy any genesit merely permits more of them to occur in homozygous pairs. Genes that favor development of both desirable and undesirable characters may become homozygous. Inbreeding thus uncovers many recessive genes that would otherwise remain concealed by their dominant pair-mates, or alleles (a recessive gene is one that is not able to express itself when it occurs as the pair-mate of a dominant gene, hence only the effect of the dominant gene is seen). Recessive genes generally have less desirable effects than dominant genes, so there is usually some degeneration in the average merit of individual animals when inbreeding is practiced. The chief danger of intense inbreeding, therefore, is that it may make undesirable genes homozygous so rapidly that it will be impossible to discard all the individuals that are homozygous for these undesirable genes. The chief advantages of inbreeding are:it helps to uncover undesirable recessive genes so that animals possessing them may be culled; it may beused to develop uniform and distinct families so that interfamily selection may be more effectively practiced; new and often superior groups of animals may be

167 produced by combining two or more inbred lines; it increases prepotency by increasing the chances that animals will pass on their traits to their offspring; and it is useful in maintaining a high relationship of stock to an especially desirable ancestor. Not all lines developed in any program with swine, or with other classes of livestock, will be valuable for use in livestock improvement. For exarnple, it is becoming apparent that only a part of the 46 inbred lines of swine on hand in the United States Regional Swine Breeding Laboratory program will merit maintenance and use for improving purebred herds and for extensive use in pork production. Some wastage of lines is inevitable. Many inferior lines of maize have been discarded, and the same will apply to inbred lines of livestock. Lindstrom (1941) made a survey of the results of inbreeding of maize in 1939, and estimated that only 2.4 percent of a total of about 30,000 inbred lines developed in the United States during several previous years had proved useful. The expense of developing an inbred line of livestock is of course much greater than for a line of corn. For this reason, itis generally desirable to guide the development of lines as much as possible by selection, and to test them thoroughly before deciding to retain or discard them. But, for thesame reason, itis necessary to be ruthless in discarding lines, once itis clearly demonstrated that they can make no worthwhile contribution to improvement, rather than to follow a natural desire to retain expensive (but not valuable) stock with the hope that it may prove useful. The outstanding inbred lines of swine may be used for crossing. withnon- inbred stock or for crossing with other inbred lines to produce market hogs, or they may be used for crossing with other lines to develop still better lines from which stock will be available for use in commercial productionor for improving purebred herds. The situation will be somewhat different for cattle and sheep than for swine. Since such a large proportion of the fernale offspring in inbred lines of cattle and sheep must be retained for replacements, the nutnbers that can be used for crossing with males from other lines for commercial production will be small. Experimental work is underway at several institutions to test the various ways of utilizing inbred lines, and further results are needed before final recommendationscan be made.

Crossing Crossbreeding for the production of market animals has been practiced for many years, particularly with swine, sheep, and beef cattle. By this method of breeding, producers have taken advantage of the increased productivity

168 (called hybrid vigor or heterosis) that frequently results from thecrossing of distinct types and breeds. The most extensive experimental work in this field has been withswine. Lush, Shearer, and Culbertson (1939), of Iowa State College, U. S. A., have summarized the results of the important experiments in this field. They point out that any one piece of work, especially one inwhich small numbers of pigs were used, scarcely appears enough byitself to prove beyond question that there is a real advantage in favor of crossbreeding. Yet, almost every piece ofwork indicates that such an advantage is probable. The Iowa workers conclude that the combined weight of all the scattered evidence is overwhelming in indicating that crossbreeding results in increased production. Crossbred pigs tend to be somewhat more vigorous and thrifty than would be expected from the average of the two parent breeds. Because of this added vigor, crossbreds generally show a lower death rate up to weaning., and consequently larger and heavier litters are weaned. Also, they generally gain a little more rapidly on a little less feed than the purebreds. For the same reasons, the crossbred gilts or sows, when used for breeding, canbe expected to wean slightly larger and heavier litters than purebreds. Lush and his co- workers emphasize that these results can be expected on the average, but they should not be expected to happen every time a cross is made, any more than slightly loaded dice should be expected to turn up a winning combination every time they are thrown. Three general systems of crossbreeding can be practiced by the producer of market hogs: Purebred or high-grade females of one breed and purebred boars of another breed can be used for the productinon of each crop of pigs. This plan is simple, but it means that replacements of sows must be purchased or produced in a subsidiary breeding program. Another plan is called crisscrossing, in which boars of two breeds are alter- nated in producing each new generation of pigs from dams saved from the previous generation. This plan takes advantage of any hybrid vigor expressed in the ability of the crossbred dam to raise large vigorous litters, and eliminates the necessity of purchasing sow replacements. Still another plan utilizes three breeds of boars. It is similar in all other respects to crisscrossing. Our knowledge of the results that can be expected from crossbreeding beef cattle has been increased in recent years through work conducted co- operatively at Miles City, Montana, by the U. S. Department of Agriculture

169 and the Montana Agricultural Experiment Station. The experiment was planned to test the possibility of maintaining heterosis through three-breed crossing. The first cross was Shorthorn bulls on Hereford cows. The first generation, Fi females (offspring of Shorthorn bulls and Hereford cows), were mated to Aberdeen-Angus bulls, and their triple-cross female offspring were mated to Hereford bulls. The latter phases of this work have not yet been completed, but results thus far indicate that three-breed crossing may be an effective method of increasing productivity in beef cattle. Some resultsare: Fifty-seven Pi steers (Shorthorn X Hereford) were compared with 67 Here- ford steers. The crossbred calves gained more rapidly in the feedlot andwere heavier at the time of marketing. Crossbreds had fewer digestive distur- bances, and they also had higher dressing percentages. Differences in efficiency of feed utilization, slaughter grade, and carcass grade were not significant. Fifty-three Fi and 55 Hereford heifers were also compared. The crossbred heifers were heavier at birth and weighed 3.3 Kg. (7.2 pounds) more at weaning time. At 18 and 30 months the differences in favor of the crossbredswere 22.7 and 40.0 Kg. (50 and 88 pounds), respectively. Results with offspring produced by mating Aberdeen-Angus bulls to Fi females show that the triple-cross steers weighedmore at weaning and at the end of the feeding period, gained more rapidly during the feeding period, sold for more per pound and per head, hada higher dressing percentage, and returned more per head above feed and marketing costs than the Hereford steers with which they were compared. The triple-cross heifers also weighed more at weaning and at 18 months, and were given higher scores at 18 months than Hereford heifers raised under identical conditions. Therewere indications that the triple-cross calves had a faster rate of gain before weaning, buta slower rate after weaning than Fi calves. Further work is needed to determine the part that continued three-breed crós'sing can play in commerical beef production. Management of animals in several groups at breeding time will make it difficult formany producers to follow. Crisscrossing in which only two breeds are used should bemore practical, and its use should be tested further experimentally. If the breeder chooses to follow an inbreeding plan, the coefficient of inbreeding may be built up at varying rates, dependingon the objectives of the program and the success of each series of matings. If crossbreeding is followed, the breeder must either dependon other breeders for replacements as needed or maintain his own breeds for crossing. Many breeders do not follow either inbreeding or crossbreeding schemes ina definite way, but either consciously

170 or unconsciously follow a system of more or less random breeding,so that the coefficient of inbreeding remainsnear zero. Such a system involves the mating of unrelated animals, so it is a system of crossing,even though it may be done within a breed or type, but it cannot be called crossbreeding, which implies mating animals of different breeds.

Developing New Breeds

Developing new types or breeds tofitspecific environmental conditions will be an important aspect of animal breeding operations inmany parts of the world. Both the difficulties and the possibilitiesmust be fully recognized. Many breeds of livestock have been developed. Theyvary widely in traits and adaptability. But circumstances sometimes arise in whichno one of the existing breeds meets all the requirements of the breeder. Under such circumstances, it may be desirable to develop a new breed, combining characteristics oftwo or more breeds. An example of this is the Columbia sheep, which is sufficiently well established to be recognized as a breed (seepage 27). It has been rather common range practice for several decades, insome western areas of the United States, to crossbreed sheep by mating range ewes that predominate in Rambouillet or other fine-wool breeding withrams of long-wool breeds, such as Lincolns and Cotswolds, in order to get larger ewes that produce more pounds of lamb and marketable wool than can be produced with fine- wool ewes of the parent stock. Although the practice has advantages, it has given rise to considerable periodic variation in flocks because crossbred ewes that were produced in this way were, as a rule, alternately mated to fine-wool rams and then to long-wool rams. Development of the Columbia sheep was an effort to contribute stability to the production of large range ewes. This breed is, in general, the result of crossbreeding select Lincoln rams with Rambouillet ewes and proceeding from this original crossbreed foundation by mating the most select first-cross rams with carefully selected first-cross ewes and interbreeding the rams and ewes descending from them. This undertaking was pursued at Laramie, Wyoming, from 1912 to 1917, and since then at the United States Sheep Experiment Sta- tion, Dubois, Idaho. The Columbia is a white-faced sheep that is large, vigorous, moderately low- set, polled, and free from wool blindness and body wrinkles. The good body length balances well with the width and depth. It is especially well-fleshed in the loin and has a square rump and a good leg of mutton. Mature rams range in body weight from 87 to 114 Kg. (190 to 250 pounds), whereas mature ewes

171 range from 61 to 70 Kg. (135 to 155 pounds) under rangeconditions in the fall. On the average, mature Columbia ewes produce about 5.5 Kg. (12 pounds) of unscoured wool per year, which, on a commercial basis, yields approximately 50 percent scoured clean wool. The average length of staple in fleeces of 1 year's growth is approximately 9 cm. (31/2 inches). Mature rams produce fleeces weighing 8 Kg. (18 pounds) or more after a growth of 12 months under range conditions. The annual length of staple for fleeces of rams averages about 95 cm. (31/4 inches). The fleece tends to stay well together in storms. DesiAible market grades of the wool from Columbia sheep, on the basis of fineness, as determined commercially, are three-eighths blood and quarter blood. Work of this type is also under way at other places and with other types of livestock. The U. S. Department of Agriculture, working in co-operation with the Office of Indian Affairs of the U. S. Department of the Interior, is developing a type of sheep adapted to the semiarid ranges of the Southwest and pro- duces a good-quality rug wool suitable for hand weaving. This work is conducted at the Southwestern Range and Sheep Breeding Laboratory, Fort Wingate, New Mexico (see page 59). At its Iberia Livestock Experiment Farm, near Jeanerette, Louisiana, the U. S. Department of Agriculture is establishing and testing new lines of cattle containing varying amounts of zebu and Aber- deen-Angus blood (see pages 85-89). The object of this latter work is to develop a type or types of beef cattle that can perform satisfactorily in the subtropical conditions along the Gulf of Mex- ico. Work is also under way with swine, in efforts to develop improved types having more lean and less fat, by combining the Danish Landrace (a bacon type) with various domestic and imported breeds of the fatter, or lard, type. The U. S. Bureau of Animal Industry has a numbei- of these experimental lines at Beltsville, Maryland, and one at its Range Livestock Experiment Station in Miles City, Montana. The Minnesota Agricultural Experim. ent Station is also developing some new lines of swine. There are other experimental efforts of this type, but these illustrate the nature of the work being done. The development of a new breed is not a task to be undertaken lightly. A definite need for a new type should be clearly evident before such a project is started. Facilities should be available to handle a large number of animals and to continue the project for many years, so that the new type can be well established. Those planning and supervising the work should have a clear understanding of the genetic principles involved. Work like this is obviously limited to government experiment stations and to a limited number of private breeders who have unusual facilities and are willing to venture afield from established breeding practices.

172 Reproduction

Maintenance of a satisfactory level of reproduction is essential to thesuccess of any breeding program. No attempt can be made here to deal with this aspect of the problem, other than to emphasize that in measuring the performance of an animal, strain, or breed, the ability to reproduce at a satisfactory level is of major importance.

Hybridizcition Hybrid animals find their greatest usefulness in animal husbandry practice as producers of work, meat, or milk, and not as breeding animals to be used in continuing improvement programs. The mule, for example, is used for work in many parts of the woild, but because of sterility cannot perpetuate itself. The pien niu (hybrid cattle and yak) is another example. The males are sterile, but females can be mated to yak or cattle bulls. Attempts have been made to hybri- dize cattle and bison, to develop a type that could withstand the cold winters of the northern United States and Canada; here again difficulties were encountered with reproduction. The experience is, in most cases, that hybridization is a method of producing utility rather than breeding animals.

173 VII IMPROVING THE ENVIEZONMENT

A detailed discussion of livestock management, nutrition, disease and parasite control, and other environmental factors is outside the scope of this publication. However, it must be recognized that in many areas substantial improvement in the efficiency of livestock production can be obtained by improving the environment. The extent to which the environment can be improved must, of course, be examined in relation to the cost and the value of the increased products that would result. Restrictions laid down by nature place definite limitations on the extent to which such improvements are economically sound in many parts of the world. Throughout this publication, emphasis has been placed on the importance of breeding and producing animals that can perform satisfactorily within the limitations of the environment. Obviously, the possibilities of improving the environment, coincident to improving the livestock of an area, must also be considered in long-range breeding programs. Many factors must be considered in any attempt to improve the conditions under which livestock are maintained. For the most economical production, maximum use must be made of range and pasture lands. Management practices should be so designed that the maximum yield of animal products is obtained per unit of land. Winter feed supplies must be provided, by harvesting and storing hay, silage, or other roughage, or by reserving winter grazing areas. Supplemental feeding of salt and also of certain minerals may be necessary in order to avoid deficiencies. Adequate calories should be provided in a well-balanced ration', since much feed is wasted by inefficient use of unbalanced rations. Diseases and parasites must be controlled if production is carried out efficiently. Housing or other shelter is needed in many cases to protect livestock fromstorms, cold, and sun. Obviously, the amount of attention and the kind of attention that should beiven to these factors will vary with climatic and other conditions. These problems are mentioned to re-emphasize the fact that the development of every animal depends upon its hereditary make-up and its environment, and that both sets of factors must be considered in livestock improvement.

174 VIII COPCU !SION

There is ample evidence to demonstrate that adaptabilityto the environment is one of the important factors to consider when decidingupon the type of stock to use in a livestock enterprise. This holdstrue whether the environmental conditions are favorable or unfavorable. Ina good environment, the profitable animal will be one that is able to produce ata maximum level with ample feed of good quality and other optimum conditions of livestock production. In a less favorable environment, greater emphasismust be placed on ability to survive and less on immediate efficiency in transforming feed into usablepro- ducts. If environmental conditionsare rigorous because of high temperatures, scanty feed, feed of poor quality, severe winters, high elevation, or other factors, then ability to survive and reproduce in the face of such obstacles becomes the first consideration in selecting stock. The most productive types of livestock have been developed in regions where ample feed is produced and where temperate climatic conditions prevail. These regions are also those in which the economic status of the people is best and where considerable emphasis has been placedon research and extension or advisory activities designed to assist livestock producers in their efforts to improve their animals. In less productive regions, the limitations laid down by nature have prevented development, by the livestock producer, of animals highly specialized for meat, milk, wool, or work production. Gen- erally poorer economic conditions have also hindered the development of highly competent research and extension services to assist the livestock owner. It is not surprising that livestock producers and agricultural leaders in less developed regions have, in many instances, obtained stock from more highly developed regions to use in improving the animals native to their own regions, or to replace them. The animal that has been developed to a highly specialized degree for beef, milk, wool, or work production, under favorable environmental conditions, stands in sharp contrast to many types native to underdeveloped areas, when only individual merit in the usual sense is considered. But the contrast is often as marked in the opposite direction when the "improved" animal from a favorable environment must meet the tests of surviving and reproducing itself in the tropics, on semiarid tracts, or in other areas to which it is not adapted. The lessons to be learned from previous efforts to introduce improved stock from the temperate zones into regions having less favorable environments

175 should be heeded in further attempts to improve livestock in the less-developed areas. Workers planning such work should also study the results of experimental breeding projects that have been carried out to develop types of animals adapted to special conditions, as well as the lessons to be learned from several types of domestic animals, not mentioned in most present-day animal husbandry textbooks, that have unique adaptabilities to the respective conditions in which they are produced. Conditions that prevail on a large portion of the world's land area are not favorable to production of highly developed beef and dairy cattle, large draft horses, or other highly specialized livestock. In many of these less favorable areas, production of livestock adapted to the local conditions is the only way in which the land may be utilized effectively. In others, particularly in the tropics and subtropics, there is need for milk and meat to supplement the human diet which is obtained largely from plant sources, and animals from temperate regions have not proved well adapted to conditions that prevail generally in these regions. The material in this volume has been assembled to make available to animal breeders and all workers interested in livestock improvement much of the information having a bearing on the breeding of livestock adapted to unfavorable environments. No attempt has been made tocollectallthe pertinent facts, but sufficient examples have been set forth to illustrate the dangers of introducing unadapted types, and to indicate the possibilities of improving livestock under unfavorable conditions, either by selecting within native types, introducing more productive types from other regions where similar conditions prevail, or developing new types adapted to specific sets of conditions. Livestock occupy a large place in the agriculture of all countries. In many countries there is need for much more attention to the solution of breeding problems upon which livestock improvement depends. Work has lagged in this field because of inadequate funds and personnel, hesitancy oft the part of government administrators to embark on the relatively long-range programs that are required in livestock improvement work, and a general lack of understanding of the contribution that could be made to the welfare of many countries by making full use of existing knowledge of animal breeding. Herein lies one of the most fascinating and productive lines for agricultural improvement, and one to which many governments could profitably direct their attention.

176 LTh ITED

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