The body composition, in terms of percentages of muscle, fat and bone of carcass or empty body weight (EBW), was estimated in a sample comprised of 44 bulls, born in 1995, from the selected herds for weight at 378 days (W378) at Sertãozinho Experiment Station (SP-Brazil) and finished in a feedlot until slaughter. The sample of each herd, representing it's mean for W378, was 9 for each group, Gir (Gi); Nellore (NeS); Control Nellore (NeC), Caracu (Ca) and 8 for Guzerá (GuS). The slaughter was at 580 days of age with a body condition score averaging 8 (1-9 scale). The estimates were obtained either by predicting equations of muscle, fat and bone amounts (estimates 1) or percentages (estimates 2) utilizing the information of the 9th-11th rib section and other slaughter traits. Average values for the two estimates for muscle, fat and bone carcass percentages were: Gi (65.9; 18.2 and 15.8); GuS (64.1; 21.3 and 14.6); NeC (63.0; 21.2 and 15.7); NeS (62.6; 21.3 and 16.0) and Ca (64.2; 17.1 and 18.6). Correspondent values for % of EBW were: Gi (41.5; 11.5 and 10.0); GuS (39.1; 13.0 and 8.9); NeC (40.0; 13.5 and 10.0); NeS (39.4; 13.4 and 10.1) and Ca (39.4; 10.5 and 11.4). The selection for post-weaning weights, observed by comparing the two Nellore groups, did not promote any change on body composition of these animals. The muscle proportion for the animals of the other groups were also similar. The percentages of kidney and pelvic fat, related to EBW, were also similar among genetic groups but the carcass and EBW fat percentage were lower for Gi and Ca. The body composition estimates for the two kinds of equations were in agreement except for bone percentages in the Ca group.
selection; body composition; Nellore; Gir; Guzerá; Caracu
