The objective of this study was to evaluate digestible lysine levels for free-range broiler hillbilly, from 28 to 56 days old. We used 720 naked neck chickens slow-growing Label Rouge strain males, distributed in a completely randomized design with six digestible lysine levels (0.800, 0.850, 0.900, 0.950, 1.000 and 1.050%), six replicates of 20 birds each. The lysine levels did not influence (P>0.05) broiler performance in accumulated periods 28-35 days, 28-42 days and 28-49 days. There was no effect (P>0.05) of treatments on feed intake and feed conversion in the total periods (28-56 days). Effect was observed (P<0.05) of lysine levels on body weight at 35 days, final weight and weight gain from 28 to 56 days old. There were no differences (P>0.05) for carcass and breast weights of abdominal fat, thigh + drumstick, back, wing and fat deposition between the levels of lysine. The carcass weight and breast varied (P<0.05) quadratically depending on the levels of dietary lysine. Increased breast weight provided an increase of carcass weight, a fact explained by the increase (P<0.05) in protein deposition according to the level of lysine that can be considered an indication of improved efficiency of utilization of nutrients. It is concluded that the level of 0.910% meets the requirement of digestible lysine for broilers hillbilly type, from 28 to 56 of age.
amino acids; carcass yield; naked neck; nutritional requirement; performance