Twins in Dairy Cattle

Cromwell Argus, Volume LXX, Issue 3627, 3 July 1939, Page 7

Twins in Dairy Cattle

An American Viewpoint Dairy cattle breeders know through experience that it is not desirable for their cows to have multiple births. It Is quite an ordeal for a cow to give birth to twins or triplets and usually results in a greatly lowered production of milk In the following lactation period. When the twins consist of a male and female, the latter Is usually sterile or commonly termed a “free martin.” The reason for this sterility is now quite generally known. When the two unborn calves have a connected blood supply it is thought that there is a harmone produced by the male sex glands which inhibits the proper development of the reproductive organs of the female and an imperfect individual results. However, if the two unborn calves are in separate membranes or do not have a connected blood supply even though in the same placenta, the female will be just as normal and will be as fertile as though born singly. It is therefore important, especially in tbe case of valuable breeding cows, to observe whether there are two separate membranes, or sacs, when the calves are born. If so, the female will be normal. When both calves are enclosed in one placenta it is sometimes difficult for the farmer to determine if there has been a connected blood supply between the two individuals. A veterinarian can answer this question upon examining the placenta. “Identical” Twins A case of identical twins in cattle has never been reported. To be identical the individuals are formed by a splitting of one fertilised egg cell. They will be identical in every respect, such as sex, physical characteristics, and producing ability. Authorities on breeding say that multiple births in cattle are hereditary and if it were desirable it would be comparatively easy to develop families with a high twinning tendency. Apparently this characteristic has already been established in some herds. In a small herd of registered Holsteius near Flint, Michigan, there have been reported .22 sets of twins and one set of triplets in tbe past 11 years. One cow in the herd has given birth to one set of triplets and tw r o sets of twins, all females, in three successive parturitions. At Morris, Illinois, is another cow which has given birth to eight heifer calves in four years. When so many of the offspring are females, as in these two instances cited, a herd can quickly be built up and may seem to be an advantage. However, it is just as likely that the twins will be of both sexes, in which case many of the females, probably 90 per cent., will be sterile, and thus be lost to the breeding herd.—E. M. Clark, Fieldman, The Holstein-Frieslan Association of America.