Birth Weight and Gestation Period in Purebred and Crossbred Dairy Cattle

Abstract

Data consisted of birth weights and gestation periods of 478 live, single-birth calves born in generations 4 and 5 of the Illinois crossbreeding experiment. The mathematical model included effects of breed groups, sires within breed groups, parity, sex of calf, and age of dam at calving as a covariate. For the two generations, crossbreds averaged 35.9 kg whereas purebreds averaged 34.6 kg; thus, crossbreds were 3.8% heavier than purebreds. The gestation period of crossbreds was 1.2 days shorter than that for purebreds. Male calves were 2.82 kg heavier and were carried 1.34 days longer than females. There were significant differences between the breed group means for birth weight and gestation period for both generations 4 and 5. The effect of parity and age of dam at calving were not significant in either generation. © 1974, American Dairy Science Association. All rights reserved.