Differences among dietary protein levels suggested in the literature point out to the need for better evaluation of protein requirements of growing lambs, raised in drylot on a high-concentrate diet. This study evaluates the influence of crude protein (CP) levels in high concentrate diets on performance and carcass traits of ram lambs, confined for 56 days. Forty eight (48) Santa Ines lambs (initial body weight 18.4 ± 0.4 kg; 86 ± 2 days old) were fed 4 experimental diets containing 14, 16, 18 or 20% CP, in a completely randomized block design. Diets consisted of 80% concentrate and 20% sugarcane bagasse. There were no differences in average daily gain: values of 228, 220, 230 and 231 g d-1 were obtained for diets containing 14, 16, 18 and 20% CP, respectively. There were no differences in dry matter intake and feed conversion: values were 1.03; 1.02; 1.08 and 1.10 kg d-1; 4.19; 4.28; 4.35 and 4.44 kg DM kg-1 gain for diets with 14, 16, 18 and 20% CP, respectively. Plasma urea nitrogen concentrations increased linearly as diets contained more CP. There were no differences in carcass traits.
carcass; drylot; hair sheep; high grain diet