Early recognition of the free-martin condition in heifers twinborn with bulls.

A freemartin, according to definition by Webster, is a sexually imperfect, usually sterile, female calf, twinborn with a male. Dairycattle-breed associations refuse to register a female twinborn with, a bull until after she has freshened. The possibility that such individuals will be capable of reproduction is so slight that many breeders destroy them soon after birth. However, breeders of high-producing herds, in which heifer calves are valuable, are often willing to spend the time and expense to raise such individuals to breeding age in the hope that they will prove to be sexually normal, A number of cases of twin births involving both sexes have occurred in the dairy herd of the Bureau of Dairy Industry at Beltsville, Md. The results of studies of the females of these mixed twins are presented herein to provide additional knowledge about the nature of the abnormalities found in freemartins, with the hope of furnishing criteria that will aid in determining at an early age, whether the female of mixed twins is a freemartin or is normal.