The document attached has been archived with permission from the World Congress on Genetics Applied to Livestock Production.Genetic effects on pre- and post-weaning body weight and developmental traits of Jersey and Limousin cross cattle has been reported (Afolayan et al., 2001). As in this earlier study which indicated the importance of epistasis at older ages, maternal effects (Meyer, 1992) and heterotic effects (Pitchford et al., 1993) have also been found on post-weaning growth traits of some breed of beef cattle. Genetic improvement programs in beef cattle could be enhanced through understanding of the genetic effects on live animal traits at various ages. However, the value of beef cattle lies better in their ability to efficiently produce a carcass composed of optimal proportions of muscle, bone and fat at market weight (Tatum et al., 1986). In essence, the knowledge of the genetic effects on different carcass components is of more importance to the breeders/producers of livestock. This study, therefore, examines the estimates of four genetic effects on predicted carcass traits using live-animal measurements
