BODY WEIGHTS AND GAINS OF CALVES FROM PUREBRED AND CROSSBRED SHORTHORN COWS

Body weights and average daily gains of 187 calves obtained by mating Angus × Shorthorn, Charolais × Shorthorn, Hereford × Shorthorn and Shorthorn cows with Shorthorn bulls were compared to evaluate the performance of the crossbred cows. Birth weights of calves from Hereford- and Charolais-sired crossbred cows (34.7 and 34.4 kg, respectively) were significantly heavier than those from the Angus cross (31.9 kg) or purebred Shorthorns (31.8 kg). The calves with Charolais ancestry weighed 209 kg at weaning and were 16, 18 and 32 kg (P < 0.05) heavier than those with Angus, Hereford or pure Shorthorn ancestry, respectively. They were also superior (P < 0.05) to the other three groups in preweaning average daily gains at three intervals. Breed group, sex, and parity were significant sources of variation in most of the traits studied. Phenotypic correlations between weights and gains were positive and highly significant. The highest estimate (0.89) was found between weights at 120 and 180 days of age.