Sire x ecological region interaction in Bonsmara cattle

Abstract

The possible interaction between sire and four ecological regions in which Bosmara cattle are mainly found in South Africa was investigated. Birth and weaning weight records of 43 628 registered Bonsmara calves born between 1976 and 1997 from 18 herds were available. Restricted Maximum Likelihood (REML) procedures were used in the analyses. Genetic correlations and expected correlated response to selection were estimated assuming the same trait (e.g. weaning weight) to be a different trait when measured in each of four different regions. The results indicate that for the purpose of genetic evaluation, the three bushveld regions need not be separated, but that it would be advisable to consider the highveld region as a separate environment. Selection of bulls bred on the Highveld for the purpose of genetic improvement in the bushveld regions is likely to be less effective than selection of bulls bred anywhere in the bushveld and conversely. The results have also, once again, confirmed that the interaction between sire and contemporary group (HYS) is usually more important than between sire and any designated region.