Heterosis from Crosses among British Breeds of Beef Cattle: Fertility and Calf Performance to Weaning

Records of 572 straightbred and crossbred matings of Angus, Hereford and Shorthorn cattle, collected over a 5-year period, were analyzed by least squares procedures to estimate the amount of heterosis from breed crosses. This procedure adjusted calf measurement data for the environmental effects of sex, year and age of dam (year, age of dam and parity were completely confounded), as well as for age in the case of weaning weight. The number of cows exposed to mating varied from 118 during the first season to 112 during the last season. The most important finding was a 10% advantage in calves weaned from crossbred matings, indicating heterosis for fertility and livability. There was evidence of heterosis in birth weight, preweaning growth rate and weaning weight. Feeder grade at weaning was slightly but not significantly lower among the crossbred calves. Differences existed among breeds in maternal environment in some breed combinations for growth rate, weaning weight and feeder grade at weaning.