The objective of the present study was to evaluate the effect of different levels and rates of protein degradation on the performance of Nellore animals in their post-weaning phase on Brachiaria brizantha ‘Marandu’ pastures. The following treatments were used: protein-energy supplement containing 25% CP (C-25); protein-energy supplement containing 40% CP, with 1/3 of the CP from urea, and 2/3 plant-derived (40–1/3NPN); protein-energy supplement containing 40% CP, with 1/2 CP from urea, and 1/2 plant-derived (40–1/2NPN); and protein-energy supplement containing 40% CP, with 1/3 of the CP plant-derived, and 2/3 from urea (40–2/3NPN). The experimental period was from June to September 2013, divided into a period for acclimation, and three 28-d periods. The experimental areas consisted of 12 paddocks averaging 2.3 ha, totaling 28 ha. Eighty-four (84) uncastrated Nellore cattle at 15 mo of age, with an initial weight of 332 ± 6.19 kg, were used. Animals were weighed every 28 d to determine the daily weight gain (DWG). The experimental design was completely randomized, wherein the initial animals’ BW was used as a co-variable, and paddocks were considered the experimental unit. Data were analyzed as repeated measures over time in mixed models, with means compared by the t-test at 10% significance. No effect of supplements was found on DWG (0.673 kg; P = 0.96). There was also no interaction between supplements and experimental periods (P = 0.76); however, the periods altered the animal performance (P = 0.02). The initial period provided a 30% higher DWG than the others (0.842, 0.573 and 0.603 kg/d in the first, second, and third periods, respectively). Treatment did not alter BW significantly (380 kg ± 5.24; P = 0.90). In conclusion, different levels and rates of protein degradation do not modify the animal performance.