Selection indexes for bulls of beef cattle

Breeding work in a beef cattle herd involves breed-ing for fertility, growth and carcass traits. Genetic and economic parameters are input data for the con-struction of selection indexes. Breeding values of many traits that can be combined in a selection index are sources of information. Many authors studied the estimation and choice of input parameters and methods of selection index construction. MacNeil et al. (1991) determined heritabilities and genetic correlations for post-weaning growth and feed intake. Gutiérrez et al. (2002) calculated genetic correlations between type traits, calving date, calving interval and age at first calving. Arango et al. (2002) determined genetic parameters and genetic correlations for weight, height at sacrum and body condition score (BCS) in crossbred cows of Aberdeen Angus and Hereford breeds. Genetic relationships between pre- and post-weaning traits of calves of the Aberdeen Angus breed (weight, visual evaluation of body conformation, muscle score and size) were investigated by Cardoso et al. (2004). Dodenhoff et al. (1998) determined genetic parameters for birth weight and weaning weight. Eriksson et al. (2004) estimated genetic correla-tions between calving difficulty and carcass traits for Charolais and Hereford cattle while Johnsto