Four hundred Avian Farms male broiler chicks from 1 to 21 days of age, with average weight of 35 ± 0.15 g, were kept under high temperature environment, where the air temperature was maintained in 29.1ºC, the relative humidity in 59.7 ± 3.16%, the black globe temperature in 28.9 ± 0.42ºC and the black globe humidity index (BGHI) in 77.4 ± 0.59. A completely randomized design, with five treatments (1.04; 1.10; 1.16; 1.22 and 1.28% of total dietary lysine level), eight replicates and ten animals per replicate, was used. It was evaluated the effect of total dietary lysine levels on performance, total lysine intake, carcass fat and protein deposition and absolute and relative weights of organs and abdominal fat. Ration and water were ad libitum fed. The levels of crude protein, minerals and vitamins in diet met the animals requirements. It was verified a quadratic effect of total dietary lysine levels on weight gain, that increased, and on feed:gain ratio, that improved until the levels of 1.20 and 1.24%, respectively. Feed intake did not change, while the total lysine intake increased with the treatments. There was no effect of lysine levels on absolute and relative weights of heart and intestine and relative liver weight. However, absolute liver weight increased quadraticaly up to 1.17% of lysine. Considering the protein deposition rate, it was verified quadractic increase until the level of 1.26% of total lysine, while fat deposition rate did not change with lysine level. It was concluded that male broilers from 1 to 21 days of age kept under high temperature (29.1ºC) require 1.20% of total lysine, corresponding to 1.02% of digestible lysine in the diet for best performance.
broiler chicks; lysine; requirements; thermal environment
