Effect of age at weaning and post-weaning stocking rate on the growth of autumn born calves

Abstract

Autumn born calves of Hereford cows, stocked at 1.5 per ha were weaned at four, six, eight, or ten months of age and grazed after weaning at 1.9, 2.6, 3.3, or 4.0 calves per ha. The weight of the calves in the following autumn increased with increasing weaning age (stocking rates pooled); 225 kg, 229 kg, 253 kg, and 271 kg in 1969 and 196 kg, 219 kg, 250 kg, and 253 kg in 1970. Because of a sex X weaning age interaction, the liveweight of 12-month-old heifers was not reduced, by early weaning, as much as was steer liveweight. Increasing the post-weaning stocking rate of the calves reduced growth to 12 months of age but there was no interaction between post-weaning stocking rate and weaning age. The results indicated that under normal seasonal conditions on perennial pastures in southern Australia, autumn born calves will be heavier at weaning and as yearlings if weaned after rather than before eight months of age.