Relation of Milk Production to the Twinning Tendency

Abstract

Upon first thought it seems unreasonable to think of any relation between high milk production and multiple births in cattle. However, when we reflect that twinning in cattle is but of the evidences of high fertility and that high fertility has been found to be closely correlated with high milk production (1), such a relationship does not seem so unreasonable. The writer, in order to determine whether or not such a relationship does exist has made a study of a random sample of 357 dams of multiple offspring in the Holstein-Friesian breed. In this study are included the dams of all the male twins in volume 35 of the herd-book, and the dams of all the female twins indicated in volume 40, up to number 474,273. There were a total, then, of 165 dams of male twins or male and freemartin, and a total of 192 dams of female twins. The two groups were kept separate as the males are selected more rigorously than the females, and thus the dams of registered males axe more likely to have records than the dams of registered females. The A. R. O. records of the dams of the twins were compiled, the problem being, Do the dams of twins produce more milk than the dams of singles. Of course, if one group did produce more than the other, it would be indicated, not by a higher average A. R. O. production, but by a larger number of animals making the A. R. O. requirements. The table given below shows the results of the study: