Effect of degree of fatness in yearling replacement beef heifers on lifetime performance

A study was initiated to determine the long-term effect of weight and age at breeding in yearling beef heifers on lifetime performance. Thirty weaned replacement heifers in each of 3 yr were equally fed until breeding on one of three systems: (i) gain of 1 kg d−1 and bred at 350 kg (medium); (ii) gain of 1 kg d−1 and bred at 15 mo of age (high); or (iii) bred at 350 kg and 15 mo of age (low). The high group had an advantage (P < 0.05) in the number of calves produced or weaned, suggesting a greater persistency of production; however, the low group weaned heavier calves. The rearing treatments had no effect (P > 0.05) on the heifer mature weights or on the birth weights of the calves. Most of the differences detected were in the first 5 yr, at which time 50% of the heifers had already been culled. Key words: Beef heifers, rearing, lifetime performance