The objective ofthis work was to evaluate body composition and net requirements of protein andenergy for weight gain of Nellore and crossbred F1 Limousin-Nellore steers finishedon Mombasa grass pastures. Mombasa grass (Panicum maximum) pastures weremanaged under intermitent stocking during the rainy season, with a forage offerof 8% of the body weight (BW) based on the dry matter of green leaves. Twenty-foursteers were used: 12 were Nellore (386 kg SBW) and 12 were F1 Limousin-Nellore(397 kg SBW). Changes in body composition in a 104-day experimental period wereevaluated according to the comparative slaughter method. After slaughter, allbody components were weighed and representative samples of carcass (HH section)and non-carcass tissues were collected, processed and chemically analyzed todetermine body contents of protein, fat and energy in each animal. Linearizedallometric equations were fitted to describe the pattern of growth of body componentsas a function of empty body weight of the animals. The obtained equations werederived to predict net requirements of protein and energy for weight gain. Therewere no differences between Nellore and crossbreed steers regarding to proteindeposition. Nellore animals tended to a greater deposition of energy on weightcompared to crossbred animals. It is possible to obtain well finished carcassin Nellore and crossbred steers with a greater weight on tropical pastures withan adequate supply of leaves.
