Níveis de proteína bruta e suplementação aminoacídica em frangos de corte

Abstract

Three experiments were performed in order to determine the protein requirements Cobb chicks 500, males, during periods of 1 to 10 11 to 21 and 22 to 42 days of age, respectively. In experiment 1, birds were fed diets with different protein levels (19,4; 20,4; 21,4; 22,4; 23,4 and 24,4%) and supplemented with essential amino acids. In experiment 2, the diets contained levels of 18,2; 19,2; 20,2; 21,2; 22,2 and 23,2% crude protein. For the experiment 3, provided the diets contained 16,1; 17,1; 18,1; 19,1; 20,1 and 21,1% crude protein. For the experiments 1 and 2, the birds were distributed in a completely randomized design with six treatments, six replicates and 20 birds each. In the experiment 3. the birds were distributed in a completely randomized design with six treatments, six replicates and 17 birds each. The experimental diets were formulated based on corn and soybean meal being, reference 1 and 5 other treatments with 3 levels below and two levels above the requirements recommended by Rostagno et al. (2011). The parameters evaluated in three experiments were: weight gain, feed intake, feed conversion, live weight, weight fasting and carcass yield, breast, the back, thigh, on the thigh, heart wings, liver and gizzard. The apparent digestibility of dry matter and crude protein also were calculated. They were calculated intake, excretion and nitrogen balance. Data were submitted to analysis of variance and regression using the statistical package SAS (2003) the level of 5% probability. It was concluded that, in experimento1, for maximum performance, it is recommended 22.3% crude protein. For the experiment 2, it is recommended 18,2% crude protein. For the experiment 3, the recommended level is 16,1% crude protein. However, diets must be supplemented with methionine, lysine, threonine, tryptophan, arginine, valine and isoleucine.