The effect of age and parity of Afrikaner and Hereford cows on the weaning traits of their calves.
Data from a registered Hereford herd and a registered Afrikaner herd were used to investigate the influence of age and parity of the dam on the weaning traits of their calves. In the case of the Afrikaner there was a small increase in weaning traits with increase in age and parity of the dam, although not significant, whereas age and parity had a highly significant influence on all the weaning traits in the case of the Hereford. This stresses the danger in using correction factors for age of dam if not determined within the same herd. Furthermore, it points out the importance of taking into consideration parity of the dam in determining correction factors, otherwise it can lead to unjustified advantage in repect of a cow which was dry the previous year, and thus favours selection for lower fertility. Afrikaner cows have a longer productive life spanthan Hereford cows.