Maternal Productivity of Crossbred Angus × Milking Shorthorn Cows. I. Cow and Calf Weights and Scores

Abstract

Heterosis for maternal productivity in crossbred Angus (A) by Milking Shorthorn (MS) cows was studied using 240 cows of A × A, A × MS, MS × A and MS × MS breed groups. Cows were born in the fall over a 5-year period. Calves were sired by Hereford, Charolais and Red Poll bulls. Data from the first three calvings were analyzed by the method of least squares with main effects including year group, weaning group, breed of sire (S), breed of dam (D) and all first-order interaction effects. The S × D interaction measured heterosis affecting cow performance. Calf sex and breed of sire of calf were added for calf data analyses. Crossbred cows averaged 6.2% heavier than purebreds from 19 to 58 months of age with condition scores below those of Angus and above those of Milking Shorthorn. For first, second and third calvings, respectively, calves from crossbred cows were heavier than those from purebred cows by .78, .53 and 1.17 kg at birth and 6.0 (P<05), 9.8 (P<05) and 4.9 kg adjusted weight at 210 days of age. Actual weaning weight of calves from crossbred cows was 7.5 kg (3.76%) above that of calves from purebred cows. Calves from crossbred cows were .24, .46 (P<05) and .28 feeder grade point above those from purebred cows in the first, second and third calvings, respectively. Calf 210-day adjusted weight (kg) per 100 kg cow exposed to breeding favored crossbred cows over purebred cows by 6.6 kg (15.50%), 3.4 kg (8.05%) and 8.2 kg (19.22%; P<05) in first, second and third calf crops, respectively. Higher percent calf crop was the major contributor to superiority of crossbred cows. Charolais sires produced calves which were 17.6 kg heavier than those sired by Red Poll and Hereford sires.