The feedlot performance of Aberdeen Angus (AA)and Hereford (HE) steers submitted to two energy levels, in a 2 x 2 factorialscheme, being the lower level of 3.07 (12% of concentrate in the diet) and thehigher of 3.18 Mcal of digestible energy/kg of DM (32% of concentrate in thediet), was evaluated. Eight steers of each breed were used, with nine monthsof age and average initial weight of 220.31 kg. The animals were confined untilthe estimated carcass weight reached 190 kg of average minimum weight. AA animalsshowed higher DM intake per 100 kg of live weight (2.27 vs 2.10%) andper unit of metabolic weight (91.4 vs 86.4 g). Animals fed with the higherenergy level showed higher DM intakes per day (6.31vs 5.71kg), per 100kg oflive weight (2.26 vs 2.11%), per unit of metabolic weight (92.28 vs85.44g), of digestible energy (DE) (20.58 vs 18.13 Mcal/day) and crudeprotein (CP) (0.845 vs 0.759 kg/day), beyond a higher daily weight gain(1.409 vs 1.250 kg). The animals that received the lower level showedhigher intakes of neutral detergent fiber (NDF), kg/day (2.23 vs 2.07 kg) andof acid detergent fiber (ADF), kg/day (1.13 vs 1.01 kg). The DM/day, neutraldetergent fiber and acid detergent fiber intakes showed a linear behavior forfeedlot period, when the animals received the lower energy level, and a quadraticpattern when the animals received the higher energy level. For DM intake expressedas percentage of live weight and per unit of metabolic weight, a cubic behaviorwas observed, for feedlot period for the animals fed with the lower energy level,however, for the animals fed diet with the higher level of energy the behaviorwas quadratic. The digestible energy intake had a linear behavior in the lowerenergy level and a cubic behavior in the higher energy level, according to periods.
