Factors affecting weaning weight of beef cattle in a tropical environment

Abstract

Age corrected weaning weights from a commercial property in central Queensland were analysed by the least-squares method. The breeder herd composition varied from low to high grade Brahman cross cows, and Belmont Red, Brahman, Droughtmaster, Hereford and Santa Gertrudis bulls were used in a rotational crossbreeding programme. Age of dam had the largest effect on weaning weight. Cows 11 years and older, produced calves 36 kg heavier than 2-year-old cows. Breed of sire effects were highly significant (P < 0.005), with the Belmont Red sired calves being heavier than Brahman, Hereford, Santa Gertrudis and Droughtmaster sired calves. Day of birth had a significant effect on weaning weight representing an extra 0.14 ± 0.04 kg per day of age. Over the whole group, heifer calves were 4.2 per cent lighter than steers, but this varied according to the breed of sire ranging from 9.6 to -0.5 per cent.