Efeitos de planos nutricionais sobre o desempenho, características de carcaça e custos de produção de frangos de corte

Abstract

Two trials were conducted in a completely randomized design to investigate effects of nutritional plans on performance, carcass yield and composition, and costs of poultry production, males in trial one, females in trial two. It was used 450 birds in each trial, reared from one to 38 days of age, in an experimental house. In the first trial, the treatments were defined according the nutritional plans as follows: (TA) digestible lysine, methionine+cystine and threonine requirements were met, and in this treatment the levels in the starter diet were the same of the pre-starter diet. (TB) digestible lysine, methionine+cystine, threonine, tryptophan, valine, isoleucine and arginine requirements were met, in agreement with Tabelas Brasileiras 2011, adding synthetic tryptophan, valine, isoleucine and arginine. (TC) digestible lysine, methionine+cystine, threonine, tryptophan, valine, isoleucine and arginine requirements were met, in agreement with Tabelas Brasileiras 2011. The levels of tryptophan, valine, isoleucine and arginine in this treatment, were met increasing crude-protein concentration in diets. The nutritional plans had any significant influence on performance, carcass yield and compostion during overall experimental period, indicating that the recommendations of some amino acid levels are over estimated, and that feeding broilers with only one diet (pre-starter) from one to 21 days of age does not decrease the overall performance of broilers. The final cost of treatment A was lower, mainly due to the lower inclusion of soybean meal. In the second trial, the treatments were defined according the nutritional plans as follows: (TD) digestible lysine, methionine+cystine and threonine requirements were met, and in this treatment the levels in the pre-starter and starter diets were the same used by the males. (TE) digestible lysine, methionine+cystine, threonine, tryptophan, valine, isoleucine and arginine requirements were met, in agreement with Tabelas Brasileiras 2011, adding synthetic tryptophan, valine, isoleucine and arginine. (TF) digestible lysine, methionine+cystine, threonine, tryptophan, valine, isoleucine and arginine requirements were met, in agreement with Tabelas Brasileiras 2011. The levels of tryptophan, valine, isoleucine and arginine in this treatment, were met increasing crude-protein concentration in diets. The overall performance was reduced in the treatment D, which has received only one diet (pre-starter) from one to 21 days of age. The best overall performance was observed in the treatment F. The lower costs were observed in the treatments D and F, suggesting that the nutritional plan used in the treatment F is economically viable in the situation presented in this work.