Comparison of crossbred cows containing various proportions of Brahman in spring or fall calving systems. III. Productivity as three-, and four-, and five-year olds

Productivity of 3-, 4-, and 5-yr-old crossbred cows containing various proportions (0, 1/4, or 1/2) of Brahman breeding out of Angus or Hereford dams was evaluated using 489 spring-calving and 427 fall-calving records collected over a 4-yr period. Cows were bred to Limousin sires for the first 3 yr and to Limousin and Salers sires the 4th yr. Interactions between crossbred cow group and season of calving were not significant. Percentage of cows exposed to breeding that weaned a calf increased (P < .01) as proportion Brahman breeding increased, was higher (P < .01) for cows out of Angus dams than for cows out of Hereford dams, and was higher (P < .01) for spring-calving cows. As the proportion Brahman increased, the percentage requiring assistance at birth decreased, and cows out of Angus dams required less (P < .05) assistance than those out of Hereford dams. Preweaning ADG, adjusted weaning weight, weaning conformation, weaning condition, and adjusted weaning hip height increased as proportion Brahman breeding increased. Spring-born calves gained .12 kg/d faster (P < .01) than fall-born calves. However, weight at weaning was similar for the two groups; spring-born calves were weaned at an average age of 205 d, and fall-born calves were weaned at an average age of 240 d. Fall-calving cows were heavier (P < .05) than spring-calving cows, and 0 and 1/2 Brahman cows were heavier (P < .01) than 1/4 Brahman cows. These data indicate that Brahman-cross dams can be used to improve reproductive rate and increase preweaning growth rate, and thus weaning weight. Based on percentage of cows exposed to breeding that weaned a calf, spring calving was superior to fall calving. Interactions between season of calving and crossbred cow group were not significant for any of the traits examined.