Reproductive performance and growth of Shorthorn purebred and crossbred cows

Abstract

SUMMARY Data were obtained from 27 pure Shorthorn, 22 Angus × Shorthorn, 31 Charolais × Shorthorn and 27 Hereford × Shorthorn cows, during 10 years. Angus × Shorthorn cows required the least number of services per conception (1·17), had the shortest average gestation lengths (280·6 days), and had a calving percentage of 88·2% and birth weight of calf of 29·8 kg. The respective figures for Charolais × Shorthorn were 1·21 services, 281·6 days, 88·3% (the highest) and 32·9 kg (the heaviest), for Hereford × Shorthorn 1·23 services, 283·6 days, 84·4% and 31·6 kg, and for pure Shorthorn 1·20 services, 282·2 days, 82·7% and 29·6 kg. Average calf weight at birth increased with the advance in age of cow up to 5 years, then showed little change. Seventy-two per cent of the crossbred cows calved for the first time at 2 years old compared with 65% of the Shorthorns. On the other hand, Shorthorn cows had the highest twinning percentage (2·9%) and the lowest single calf mortality at birth (1·4%). The maximum body weights of Angus, Charolais, and Hereford crossbreds and Shorthorn cows were 576·8, 655·8, 6254 and 553·8 kg respectively at 7–8 years of age.