INFLUENCE OF COW SIZE AND OTHER FACTORS ON WEIGHT GAIN OF BEEF CALVES TO 365 DAYS OF AGE
A study involving three sets of data from the University of Alberta beef breeding herd (1966–67, 176 cows; 1967–68, 167 cows; 1968–70, 285 cows) was conducted to determine the influence of birth weight of calf (BW), postcalving weight of dam (PCW), and breed effect on calf performance to 365 days of age. The influence of preweaning on postweaning performance was also considered. Calves heavier at birth tended to excel in both preweaning and postweaning growth rate. A 1-kg increase in BW resulted in an increase of 2.86–4.42 kg in calf weight at 365 days of age. For male calves, PCW was negatively associated with calf weight at both 180 and 365 days of age for 1966–67 data; however, for 1967–68 and 1968–70 data, a 10-kg increase in PCW resulted in 0.70- and 0.92-kg increases, respectively, in calf weight at 180 days, and 1.96- and 2.12-kg increases in calf weight at 365 days, respectively. For female calves, a 10-kg increase in PCW resulted in 1.40-, 0.88-, and 0.29-kg increases in calf weight at 180 days of age, and 0.68-, 1.31-, and 0.31-kg increases in calf weight at 365 days of age, respectively, for the three sets of data. Breed difference explained from 22 to 43% of the variance in average daily gain of calf to weaning (ADG) but only 0.2–13.8% of the variance in postweaning average daily gain (PWADG). Male calves with higher ADG to weaning or heavier weaning weights tended to have slightly higher PWADG. A 10-kg advantage in weaning weight for male calves resulted in a 12–14-kg advantage in weight at 365 days of age.