Artificial Breeding

by RALPH W. PHILLIPS

A BULL can cover 30 to 50 cows a year under average conditions. Each time he spends millions of sperms, any of which could fertilize an egg and beget a calf. To correct such profligacy of nature, careless with the individual however concerned she may be with the species, man has developed a technique called artificial insemination, whereby semen is obtained from the male, diluted considerably, and a part of it placed manually in the cervix or uterus of the female. Thus a bull can impregnate 500 or 1,000 cows a year, or even more in special circumstances. The usefulness of good bulls and other males is multiplied manifold. There is less chance of spreading disease. The semen of valuable males can still be utilized even when they become too big or too old for natural service.

Animal breeders in the United States became actively interested in the technique a decade or so ago, although actually it is much older. The Italian scientist Lazaro Spallanzani in 1780 artificially inseminated a bitch to show that semen alone was sufficient to start normal pregnancy. The Russian Professor Elie Ivanov in 1919, after 20 years of preliminary work, set up the Central Experimental Breeding Station in Moscow to further the method.

At first some failures resulted in the United States from improper handling of semen, mismanagement of bulls, and inadequate financing of associations, but the work was successful generally, and it has become well established. In 1939, six associations of dairy cattle breeders used artificial insemination; they had 646 members who owned 33 bulls and 7,539 cows. In 1946, there were 336 associations, with 73,293 members in 29 States. These members owned 579,477 cows and were using 900 bulls. The leaders were Wisconsin, Pennsylvania, Ohio, New York, and Iowa. Another interesting comparison : In 1946, cooperative bull associations and bull studs in which natural mating is practiced had an average of 11.1 cows to a herd and 38 cows to a bull; artificial-breeding associations had 7.9 cows to a herd and 644 cows to a bull.

Artificial insemination is used mostly among dairy cattle. An example of its use with beef cattle is in the purebred Hereford herd of the Apache tribe of San Carlos, Ariz. The herd comprises about 1,000 cows, which are kept in a pasture of approximately 10,000 acres. Bulls are kept at a central plant near one of two watering places. The plant has a laboratory, four corrals, a feed barn, and breeding and semen collection chutes, built especially to handle range cattle. Cowboys check cows for estrus, and the cows in heat are brought to the central plant, or to a subsidiary set of corrals and breeding chute about 5 miles from the central plant, where they are inseminated.

Horses and sheep also are bred artificially to some extent, primarily to meet the needs of individual breeders or experiment stations. Little use is made of the technique with goats and swine. Poultrymen employ it in experimental crossing and in studies that require controlled conditions of insemination. It is useful where birds are kept in individual laying cages, but commercial breeders find its cost is relatively high compared to the cost of roosters. Breeders of broad-breasted turkeys use it to maintain fertility, because many broad-breasted males are clumsy and unable to mate efficiently. Such use is of doubtful value, however, for breeding stock from flocks developed with the aid of artificial insemination may go to flocks where natural mating is the only economical procedure. Males that cannot give satisfactory service under these conditions are of little value.

Most artificial-breeding associations in the United States started as individual units, each having its own staff and bulls and operating in a small area. More recently, a trend began toward the more efficient federated type of organization, which functions in a larger area, such as a State or a part of a State.

Usually, a number of local organizations combine to form a federated organization, and members of the local groups belong to the central association that owns or leases the barn, laboratory, and all bulls, which are kept at the central barn. Semen is mailed or shipped to the local associations. The local associations usually employ their own technicians, manage local procedures, and elect directors of the central organization. The work is financed by an equitable division of income between the central and local associations. The local associations may be incorporated as affiliates or subsidiaries of the central association. After a central association is formed, local associations can become affiliated with it.