This work was conducted to evaluate the chemical body composition of sixty three young bulls, from the Gyr, Guzera, Mocho Tabapuã, Nellore breeds, in feedlot, averaging, respectively, 376.4, 357.6, 362.0, and 368.6 kg of initial live weight. The animals from each breed were divided into five categories: initial slaughter, full fed diet containing 50% concentrate until the individual slaughter weights of 405, 450 and 500 kg, respectively, and finally the category restricted feeding fed the same diet supplying levels of protein and energy 15% above maintenance. There were no differences among breed regarding to body content of protein, fat, energy and macrominerals (Ca, P, Mg, K and Na). The animals slaughtered at higher weights showed lower percentage of body protein and macrominerals (Ca, P, Mg, K and Na), and occurring the inverse to the body fat.
beef cattle; body composition; nutritional requirements; Gyr; Guzera; Mocho Tabapuã; Nellore
