Abstract

Two experiments studied the effects of herbage allowance in the latter half of pregnancy on the performance of 18-month beef heifers. In Experiment 1, 54 heifers were offered daily allowances of 4.5 (H) or 3.3 (M1) kg DM/100 kg live weight (LW), and in Experiment 2, 64 heifers were offered 3.1 (M2) or 1.9 (L) kg DM/100 kg LW. Average daily gain to post-calving weight (net ADG) for the H and M1 heifers in Experiment 1 was 0.46 and 0.34 kg/d (P<0.001). The post- partum anoestrous interval (PPAI) was short in both groups (H+ 42.7 and M1 = 49.2 days; P<0.10). H calves were 1.8 kg heavier at birth and 7.6 kg heavier at weaning than M1 calves (P<0.05). In Experiment 2, M2 and L heifer net ADG was 0.23 and -0.03 kg/d respectively (P<0.001). The PPAI was 28.4 d shorter for M2 than L heifers (P<0.001). Birth and weaning weights of M2 calves were heavier by 1.8 kg (P<0.07) and 14.0 kg (P<0.05) respectively than those of L calves. Results suggest that a herbage allowance of around 3 kg DM/100 kg LW over the latter half of gestation may be adequate for satisfactory performance of yearling-mated heifers.

JM, Suttie, ID Corson, and PF Fennessy

Proceedings of the New Zealand Society of Animal Production, Volume 44, , 167-170, 1984