Developing New Breeds

Many breeds of livestock have been developed. They vary widely in traits and adaptability. But circumstances sometimes arise in which no 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 of two or more breeds. An example of this is the Columbia sheep, which has become sufficiently well established to be recognized as a breed.

It has been rather common range practice for several decades, in some western areas, to cross-breed sheep by mating range ewes that predominate in Rambouillet or other fine-wool breeding with rams of long-wool breeds, such as Lincolns and Cotswolds, in order to get larger ewes that produce more lambs and pounds of 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.

In an effort to contribute stability to the production of large range ewes, the Columbia sheep has been developed by the Department. This breed is, in general, the result of cross-breeding 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, Wyo., from 1912 to 1917, and since that time this development of the Columbia sheep by the Department has been conducted at the United States Sheep Experiment station at 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 190 to 250 pounds, whereas mature ewes range from 135 to 155 pounds under range conditions in the fall. On the average, mature Columbia ewes produce about 12 pounds of unsecured wool per year, which, on a commercial basis, yields approximately 50 percent scoured clean wool. The average length of staple of the fleeces of 1 year's growth is approximately 3 1/2 inches. Mature rams produce fleeces weighing 18 pounds or more for a growth of 12 months under range conditions. The annual length of staple for fleeces of rams averages about 3 3/4 inches. The fleece tends to stay well together in storms. Desirable 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 Department, working in cooperation with the Office of Indian Affairs, is developing a type of sheep that is adapted to the semiarid ranges of the Southwest and produces a good-quality carpet wool suitable for hand weaving. This work is conducted at the Southwestern Range and Sheep Breeding Laboratory, Fort Wingate, N. Mex. At its Iberia Livestock Experiment Farm, near Jeanerette, La., the Department is establishing and testing new lines of cattle containing varying amounts of zebu and Aberdeen-Angus blood.

The object of this work is to develop a type or types of beef cattle that can perform satisfactorily in the subtropical conditions along the Gulf of Mexico. 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 Bureau of Animal Industry has a number of these experimental lines at Beltsville and one at its Range Livestock Experiment Station in Miles City, Mont. The Minnesota Agricultural Experiment Station is also developing some new lines of swine. There are other experimental efforts of this type, but these should serve to 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 undertaken. Facilities should be available to handle a large number of animals and to continue the project for many years, so that the new type may be well established. The person or persons planning and supervising the work should have a clear understanding of the genetic principles involved. Work like this is obviously limited to Federal and State experiment stations and to the establishments of a limited number of private breeders who have unusual facilities and are willing to venture from the established breeding practices.

Maintenance of a satisfactory level of reproduction is essential to the success of any breeding program. Much work has been done in recent years on various phases of physiology of reproduction that have a bearing on fertility.

The importance of time of breeding in relation to the beginning and end of the heat period, or estrus, has received considerable attention. Data on length of estrus, time of ovulation, or release of the egg or eggs from the ovaries, speed of travel of spermatozoa in the reproductive tract, duration of life of spermatozoa in the female tract, and studies on the proportions of successful coatings when breeding takes place at various stages of estrus all bear on the problem.