Two hundred and forty male broilers of Ross strain, with initial weight of 43 ± 0.2 g, from 1 to 49 days of age, were maintained under thermal comfort (24.2 ± 3.52ºC). A completely randomized design with four nutrition plans was used: NP1 (1.1, 1.0, and 0.85% de total lysine); NP2 (1.2, 1.1, and 0.95% de total lysine); NP3 (1.3, 1.2, and 1.05% of total lysine); and NP4 (1.4, 1.3, and 1.15% de total lysine), respectively for the periods from 1 to 21 days, 22 to 41 days and 42 to 49 days of age, six replicates of ten birds until 41 days of age and of seven birds from 42 to 49 days of age. The effect of lysine level on performance, weight and yield of special cuts and edible viscera were evaluated. Weight gain, feed: gain ratio and feed intake were not influenced by treatments. However, the relative and absolute weight of breast, breast without bone and liver were influenced by treatments. Based on the performance results it was concluded that any nutrition plan met the requirements of broilers for all studied phases when they are kept under environment of thermal comfort. Considering the special cut yield values, the 2, 3 and 4 nutrition plans support the best results.
environment; amino acid; noble cuts; performance; lysine
