Influence of reproduction traits and pre-weaning growth rate on herd efficiency of different beef breed types in an arid sub-tropical environment

The efficiency of Simmentaler cross (SX), Bonsmara cross (BX), Afrikaner (AF) and Nguni (NG) cowherds to produce weaner calves under natural sweetveld conditions was investigated. The respective cowherds were selected to differ with regard to frame size (SX > BX > AF > NG). The AF cows, young (13 to 15 months old) heifers and herd had significantly lower pregnancy rates than the SX, BX and NG cows, young heifers and herds. The weaning rate for NG was significantly higher (15%) than SX, and although not significant, it was still 5 and 8% respectively higher than BX and AF. Weaning weight and pre-weaning growth parameters differed significantly between breed types (SX > BX > AF > NG). Cow efficiency was significantly lower for the AF cows than for the SX, BX and NG cows. The NG herd was more efficient than the other three herds, while the AF herd was the least efficient. Differences in herd efficiency were mainly due to differences in the reproduction rates of the respective herds. The reproduction and calf survival rates were the most important production traits that affected herd efficiency. Management practices should be adapted to maximize the reproduction rate of the females, including the young heifers, to maximise herd efficiency. South African Journal of Animal Science Vol. 36(2) 2006: 89-9