Exigências nutricionais de bovinos nao-castrados em confinamento. 1. Conteúdo corporal e exigências líquidas de proteína e energia para ganho de peso

Twelve Nellore, twelve FI Nellore-Angus, and twelve Fl Nellore-Holstein intact males, with 24 months and an average initial liveweigth of 325, 417 and 414 kg, respectively, were used in this research. Four animals from each breed group were slaughtered at the begining of the trial, The remaining animals were individually fed with a 50 percent concentrate ration and slaughtered after reaching target weigths of 450 or 500 kg for Neflore and 500 or 550 kg for crossbred animals to study body content and net requeriments for weigth gain of protein and energy. The model identity test, applyed to the regression equations of logarythm of body content of protein, fat, and energy as a fuction of the logarythm of empty-body-weigth indicated differences among Nellore and crossbred animals. Therefore, different set of equations was used for Nellore and for crossbred animals, to estimate body content and net requeriments of protein and energy. In the range of the live weigth, included in this research, the Nellore had higher net requirement for energy and lower for protein, for weight gain than the crossbred animals.