Effect of energy, lysine and methionine and cystine levels on performance and carcass yield of broiler chickens

The effects of dietary energy, lysine and methionine + cystine levels on performance, carcass and cuts yields of male and female broiler chickens were evaluated. The experiment was analyzed as a completely randomized experimental design in a 3 × 2 factorial arrangement composed by six diets and eight replications (four males and four females). The diets consisted of energy (low, middle and high) and lysine and methionine + cystine (standard and + 10%) levels and of raising period (1 to 45 days old). Male broilers fed diets with 3,000, 3,100 and 3,200 kcal/kg, respectively, in the initial, growing and standard levels of amino acids showed better weight gain at 45 days old, however, for the best breast yield, the highest amino acid level was the most indicated. Middle energy and high amino acids levels are indicated for greater weight up to 40 days old, in females.