Herbage intake, ingestive behaviour, and growth performance in unbred and once-bred Hereford × Friesian heifers

摘要

Abstract The once-bred heifer beef production system involves mating heifers at 15 months of age to calve as 2-year-olds. This study compared the performance of once-bred Hereford × Friesian heifers mated to Limousin or Charolais sires and the herbage intake of once-bred and never-bred heifers during periods corresponding to late pregnancy and early lactation in the former group. Heifers carrying Limousin-sired (LS) calves had gestation lengths slightly longer than those carrying Charolais-sired (CS) calves (290.4 versus 286.6, pooled SE (PSE) = 1.2 days, P < 0.10), but there was no effect of calf sex on gestation length. The average birth weight of calves was 40 ± 1 kg, there being no difference between female and male, or LS and CS, calves. Dystocia caused mortality rates of 19% in calves and 9% in heifer dams. Female calves had 9 kg lower weaning weights at 142 days of age than male calves, whereas the CS calves had greater weaning weights than LS calves (218.3 versus 204.9 kg, PSE = 3.6 kg, P < 0.01)....