Growth, reproduction, and carcass and meat quality characteristics of once-bred Hereford x Friesian and Simmental x Friesian heifers managed for low or high liveweight gain during mid pregnancy

The growth, reproduction, carcass and meat quality characteristics of once-bred Hereford x Friesian (H x F) and Simmental x Friesian (S x F) heifers mated to Angus sires and managed for high gain (''HG'' group) or low gain (''LG'' group) during mid pregnancy (i.e. pregnancy days 114-214 = P114-P214) were compared in this study. Liveweights at mating of S x F heifers (347 +/- 6 kg) were slightly higher (P < 0.10) than those of H x F heifers (333 +/- 5 kg). From P114 until P214, HG heifers had significantly higher (P < 0.001) growth rates (0.72 +/- 0.03 kg/day) than the LG group (0.16 +/- 0.02 kg/day). This resulted in a higher liveweight in HG heifers at P214 (P < 0.001) and P270 (P < 0.01) than in the LG heifers. Gestation length, calving score, and liveweight loss at calving were not influenced by dam genotype or mid-pregnancy liveweight gain. Liveweight gain of the 24 heifers that suckled calves was not affected by dam genotype or prior liveweight gain of the dam during the suckling period or from weaning to slaughter (an average liveweight gain of 0.33 kg/day). Calf birth weight, weaning weight, and daily liveweight gain during a 106-day suckling period were not influenced by genotype or prior liveweight gain of the dam. Final heifer liveweight was slightly lower (P < 0.10) in LG versus HG heifers (476.4 versus 512.7, PSE = 16.2 kg). Dressing-out percentage was significantly (P < 0.05) higher in H x F heifers than in the S x F group, while mid-pregnancy liveweight gain had no effect on dressing-out percentages. There was a tendency (P < 0.10) for H x F versus S x F or HG versus LG heifers to produce carcasses with greater levels of fat. However muscularity and meat quality traits were not affected by dam genotype or mid-pregnancy liveweight gain. Results are discussed in the context of beef production from once-bred S x F versus H x F heifers under New Zealand conditions.