Superior Germ Plasm in Dairy Herds

Superior Germ Plasm in Dairy Herds By R. R. Graves^ Principal Specialist in Dairy Cattle Breedings and M. H. Fohrman^ Senior Dairy Hushandman^^ Division of Dairy Cattle Breeding, Feedingj and Management^ Bureau of Dairy Industry WITH more than 26 million dairy cows spread over the entire United States, a survey of herds for superior germ plasm is a tremendous undertaking. How the survey which is the subject of this article was conducted among agricultural experiment stations and the owners of more than a thousand commercial herds is described in later pages. It is sufficient at this point to say that no similar project on so large a scale had previously been attempted in this country. Hitherto the genetic study of dairy cattle has been restricted for the most part to analysis of the hereditary make-up of the individual sire or dam. Some attempts have been made in studies in the Bureau of Dairy Industry, and more recently by the Holstein-Friesian Association, to show the inheritance for production being built in some herds through the use of a number of sires. To analyze all the sires used in herds during the entire period of record keeping, however, and to show the female lines of descent and their relationship to the various sires in a large number of herds, is pioneer work in the field of animal breeding. In the present state of genetic knowledge relating to livestock, many might call it premature to attempt a survey of progress in breeding superior germ plasm in dairy-cattle herds in which records of production have been kept over a period of years. The effort is necessarily based on the generally accepted theory that butterfat and milk production are characters inherited through quantitative factors (genes) and that on the average sires proved for ability to increase daughters' records over dams' records carry superior germ plasm and should be used in herd improvement. Neither the actual genes nor their mode of inheritance is known, though presumably there are many of them and they interact with one another in an extremely complex way. It may be pointed out, however, that this 1 other members of this Division who have assisted with the preparation of the material are W. W. Swett, T. E. Woodward, J. R. Dawson, J. B. Shepherd, C. A. Matthews, and C J. Stauber. 997 basic assumption is not essentially different from that continually used in practical plant breeding. The wheat or the corn breeder knows neither the genes that influence production nor their mode of inheritance, but by assuming that they exist and that his general theory of their operation is not too far from the truth, he is able to get results of unquestionable value. The prematurity in this case, then, does not lie in the nature of the assumption, but in applying it to an animal organism and using it on a wide scale to draw practical conclusions as to intrinsic worth— that is, to compare and grade breeding merit on the basis of the three characteristics of primary economic importance in dairy cattle: milk production, butterfat production, and butterfat percentage. These quantitative elements can be measured for individual animals and entire herds, and a practical procedure has been in use long enough to yield many data useful in the selection of sires possessing superior inheritance for high levels of production. Nevertheless there are recognized shortcomings and difficulties in the methods employed. Material on type of animals was included in the survey for the benefit of those who lay stress on conformation, and who feel that this may have some connection with productive ability. This material is available to the breeders concerned and the present plan is to publish it elsewhere than in this Yearbook. It is recognized that by no means all of the superior germ plasm in dairy cattle in the United States is included in the present survey. There is undoubtedly a great deal of it in herds for which records of production have not been kept, as well as in those for which record keeping has been intermittent or selective. In fact many of the best known breeding herds fall in the latter class and were therefore not available for use in the survey. Moreover, in many States limitations of time and available funds did not permit the inclusion even of all the herds in which records had been kept for a considerable time. The present survey, then, cannot be considered as a completed structure. It is ground work for the building of a more enlightened and constructive breeding program. Organized record keeping for dairy cattle has never attained desirable momentum and volume, though it has been advocated for many years by educational organizations and institutions. Those who keep records have used them principally for culling their low- producing cows. It has been estimated that in our dairy herd- improvement associations only about one-third of the cows produce enough to be profitable to their owners, another third just about break even, and the last third are such low producers as to lose money each year for their owners. In considering this statement it should be remembered that less than 2 percent of the total dairy-cow population are being tested through herd-improvement associations and that this 2 percent, together with the cattle being tested through breed organizations, are in all probability considerably higher producing animals on the average than the remainder of the dairj^-cow population In the lack of a constructive breeding program that w^ill produce a general improvement in germ plasm for higher producing levels, dairy farmers will continue to be burdened with a large percentage of cows that lack the inherent ability to produce sufficient milk and butterfat to render them profitable. Culling out a few low-producing cows is not a corrective for this situation. The poor cows will always 998 be in the herds to cull unless the owners follow a breeding program that will eliminate the germ plasm responsible for low production. This survey, then, shows what has actually been happening under the present system of breeding in the better herds. It offers the first picture, though an incomplete one, of the results of the testing program. The picture is incomplete because only the best results are shown. Without doubt critical consideration will bring flaws to light in the present survey, and many improvements and refinements should be possible in the future. This criticism is invited and will be welcomed. It has not even been possible to develop all the conclusions that might be draw^n from the survey. The mere analysis of thousands of survey cards, the calculations involved, and the summarizing and boiling down of details took weeks of work on the part of a large staff. The development of additional material is a task that will take some time after the present Yearbook is published. In many States, those who have made the survey and obtained the data from the farms see so much value in this new field of work that they are asking how it can be continued; how it may be placed on a permanent basis. The Origin and Bac\ground of the Present Breeds of Dairy Cattle THE links that indicate the line of descent of our domestic cattle from their wild forebears are skeletons and parts of skeletons excavated from various geological strata, lake beds, and marshes where they resisted decay to be resurrected later for painstaking study by archeologists, paleontologists, and osteologists, who forged the bony chain of evolution. Their conclusions in turn w^ere strengthened by gleanings from the drawings left by primitive man. Disregarding some confusion in early terminology and some per- sisting disagreement, it is evident that our domesticated cattle came from the wild species of the genus Bos, which is the largest genus of the family Bovidae. The wild cattle are long since extinct, but the long- horned species, B, primigenius, survived in the wild state in Europe up to the beginning of the fifteenth century (;^).^ It is believed that this was probably a variety of B, namadicus, the Asiatic wild ox. Its place in the ancestry of domestic cattle appears to be well established. Some confusion persists regarding the origin of the short-horned breeds. A small wâld species called B. longifrons is suggested as the ancestor of these cattle, but according to one hypothesis, B. longifrons—also called B, brachyceros—was a stunted type of B, namadicus. If this is true it would indicate a common origin for all domestic European breeds, although most writers believe that they came from two or more sources. The controversy may be cleared up when more bones have been unearthed. In any event, there were wild cattle in abundance when primitive man decided to add herding to hunting in order to safeguard and supplement his food supply. Presumably domestication of cattle 8 Italic numbers in parentheses refer to Literature Cited, p. 1069. 999 started with the capture and taming of young animals. Historians beUeve the formation of domestic flocks and herds began about 10,000 years ago, perhaps in Asia. Migrations and conquests brought about a mixing and blending of these early stocks. Since there was much roaming about in search of new pastures and more or less constant warfare between neighboring tribes, it is safe to assume that no thought was given to improvement of flocks and herds during the ages preceding the dawn of civilization. Early historians recount the accomplishments of kings, emperors, and nobles in the field of animal husbandry, but many of these chroniclers ¡flattered their patrons.

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