Estimates of phenotypic and genetic parameters and responses to selection in growth traits in three beef cattle breeds raised under ranch conditions in Botswana

Abstract

The objective of this study was to estimate phenotypic and genetic parameters and responses to selection in growth traits in the three beef cattle breeds raised under ranch conditions in Botswana. Data on birth (BW), weaning at 7 month (WW) and 18 month (18MW) weights were available for Brahman (n=841), Bonsmara (n=926) and Tuli (n=403) breeds collected from 1997 to 2008 inclusive by the Department of Agricultural Research, Botswana. Genetic and phenotypic parameters were estimated by fitting a multi-trait individual animal model in ASReml Programme and all significantly (p1x10-6) for each trait in all breeds. To maximise response rates trait breed specific parameters should be used for selection. There were no responses to selection in all the three growth traits across the three breeds indicating an ineffective selection index used to identify parental animals. BLUP breeding values should be used for selection especially for WW and 18MW where rapid response rates are essential to improve overall productivity.