Two experiments were conducted to determine the nutritional requirements of total methionine + cystine for Ross male broilers from 1 to 21 and 22 to 42 days old on tropical climate. The following parameters were evaluated: feed intake, weight gain, feed:gain ratio and absolute weights and yields of carcass, noble cuts (chest, thighs and drumsticks) and abdominal fat. The experiment was analyzed as a complete randomized design with six levels of methionine + cystine and four replicates of 12 animals, in a total of 288 birds for each experiment. The diets were formulated to meet the bird nutricional requirements, except for methionine + cystine levels. The diets were supplemented with DL-methionine at levels of 0, 0.08, 0.16, 0.24, 0.32, and 0.40%, resulting in experimental diets with 0.69, 0.77, 0.85, 0.93, 1.01 and 1.09% of methionine + cystine, for the period from 1 to 21 daysold and 0.61, 0.69, 0.77, 0.85, 0.93, and 1.01% of methionine + cystine, for the period from 22 to 42 days old. Quadratic effects of methionine + cystine levels on weight gain and feed:gain ratio, from 1 to 21 days old, and on feed intake, weight gain, feed:gain ratio, absolute weights of carcass and chest and yields of carcass, thighs and drumsticks, from 22 to 42 days old , were observed. According to the performance data, the nutritional requirements of methionine + cystine for male Ross broilers were estimated in 0.96 and 0.89% from 1 to 21 and 22 to 42 days old, respectively.
broiler; methionine + cystine; nutritional requirement; performance; quality of carcass
