The objective was to compare diets for feedlot lambs with two protein levels and two protein sources. 30 were confined lambs, Dorper with St. Inês aged approximately 2.5 months and initial weight of 23kg, were randomly divided into three groups: control diet (15% CP) diet high concentration of true protein (soybean meal, with 19% CP) and diet with a high concentration of non-protein nitrogen (urea, 19% CP). The design was completely randomized and the analysis of data taken by SISVAR using the Tukey test at 5% probability. No statistical differences were observed in the characteristics evaluated for performance and carcass. The diet combined with the lambs of the earning potential can explain the gain in average daily weight of 0.288kg. The body condition (1-5) average initial was 2 (thin) and the end of the experimental period being 3.3 (normal). The carcass conformation, averaging 3.68 points and the conformation of fat cover, with an average of 3.41 points can be classified as medians. The subcutaneous fat thickness, averaging 2.75mm is satisfactory to protect the carcass during cooling. It is concluded that the increase in the protein content in the diet did not improve the characteristics evaluated; and the high-protein diets no difference between the true protein use or non-protein nitrogen, using 2% urea on dry matter.
carcass conformation; carcass yield; fat thickness; soybean; urea