The objective wasto evaluate the addition of vegetable oils protected or not from rumen degradationin the diet of feedlot-finished young bulls and their effects on performanceand carcass characteristics. Thirty-five Nellore males of 402.69±14.90kg initial weight and 18±2 months of age were utilized. The animals wereconfined for 96 days, after 28 days of adaptation, and slaughtered at 532.17±30.25kg. Experimental diets were: control (715 g total digestible nutrients - TDN/kgof dry matter - DM), with addition of soybean oil or fresh linseed oil, andwith the addition of the same oils protected from rumen degradation (765 g TDN/kgDM). All diets were formulated with the same amount of protein and with a roughage:concentrateratio of 40:60, with sugarcane as the only roughage. The addition of oil, regardlessof the type and processing, resulted in greater body weight gain (1.17 and 1.41kg/animal/day), better feed (0.11 and 0.14 kg weight gain/kg DM ingested) andprotein efficiency (0.86 and 1.09 kg weight gain/kg crude protein ingested),heavier carcasses (280.3 and 298.0 kg), with better yield (54.5 and 55.5%) andthicker subcutaneous fat (5.1 and 7.5 mm backfat thickness) and with heavierprime cuts, for control diet and the other treatments, respectively. The useof soybean or linseed oil protected or not from rumen degradation only changedthe intake of a few nutrients and carcass yield and depth. Thus the additionof energy sources in the diet is beneficial for finishing feedlot bulls. Forthis addition, either soybean or linseed oils can be used, and the processingof these oils is only useful to facilitate the mixing with the other ingredientsof the diet.
