Body composition of 42 crossbreed bulls ¼ B. indicus x ¾ B. taurus of either Continental (Guelbvieh) or British (Shorthorn) paternal breed and Caracu x Nelore cows (9 months old and initial empty body weight of 243 kg), were evaluated. Six animals were slaughtered after the adaptation period to obtain the initial body composition. The other 36 animals were fed diets formulated with 9, 15 and 21% of sugar cane bagasse in natura (BIN) and concentrated. There were no significant interaction of genetic breed and level of BIN for any variable. There was no effect on paternal breed on the composition of empty body gain (EBG), with British animals with 28.9% lipid and 3.75 Mcal/kg and Continental animals 28.0% lipid and 3.67 Mcal/kg in the EBG. British animals had numerically greater fat content in the gains despite the lower initial and final empty body weights. Animals receiving diets with 15% BIN had higher rates of empty body gain, 1.21 kg/d, while animals receiving 9 and 21%, gained 1.1 kg/d. Roughage level or breed did not alter final empty body composition, however, composition of the empty body gain of animals fed 15% BIN had higher lipid and energy content (31% and 3.94 Mcal/kg EBG) compared to the animals recieving 9 and 21% BIN diets (28.6 and 25.7% lipid; 3.72 and 3.46 Mcal/kg of EBG, respectively). These results can be explained by the fact that the animals were young intact males with low final body weights. Composition, of the EBG (net energy and protein requirements) of ¾ B. taurus F2 crossbreed bulls from Caracu x Nelore cows were consistent with NRC equation for large frame bulls or frame score 8 in a 1-9 scale.
beef cattle; body composition; concentrate; fiber; requirements; sugarcane bagasse
