The feedlot performance of Aberdeen Angus (AA) and Hereford (HE) steers submitted to two energy levels, in a 2 x 2 factorial scheme, being the lower level of 3.07 (12% of concentrate in the diet) and the higher of 3.18 Mcal of digestible energy/kg of DM (32% of concentrate in the diet), was evaluated. Eight steers of each breed were used, with nine months of age and average initial weight of 220.31 kg. The animals were confined until the estimated carcass weight reached 190 kg of average minimum weight. AA animals showed higher DM intake per 100 kg of live weight (2.27 vs 2.10%) and per unit of metabolic weight (91.4 vs 86.4 g). Animals fed with the higher energy level showed higher DM intakes per day (6.31vs 5.71kg), per 100kg of live weight (2.26 vs 2.11%), per unit of metabolic weight (92.28 vs 85.44g), of digestible energy (DE) (20.58 vs 18.13 Mcal/day) and crude protein (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 showed higher intakes of neutral detergent fiber (NDF), kg/day (2.23 vs 2.07 kg) and of acid detergent fiber (ADF), kg/day (1.13 vs 1.01 kg). The DM/day, neutral detergent fiber and acid detergent fiber intakes showed a linear behavior for feedlot period, when the animals received the lower energy level, and a quadratic pattern when the animals received the higher energy level. For DM intake expressed as percentage of live weight and per unit of metabolic weight, a cubic behavior was 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 behavior was quadratic. The digestible energy intake had a linear behavior in the lower energy level and a cubic behavior in the higher energy level, according to periods.
Bos taurus; concentrate; feedlot; intake; weight gain; britanic breeds
