Two experiments were conducted to determine thenutritional requirements of total methionine + cystine for Ross male broilersfrom 1 to 21 and 22 to 42 days old on tropical climate. The following parameterswere evaluated: feed intake, weight gain, feed:gain ratio and absolute weightsand yields of carcass, noble cuts (chest, thighs and drumsticks) and abdominalfat. The experiment was analyzed as a complete randomized design with six levelsof methionine + cystine and four replicates of 12 animals, in a total of 288birds for each experiment. The diets were formulated to meet the bird nutricionalrequirements, except for methionine + cystine levels. The diets were supplementedwith DL-methionine at levels of 0, 0.08, 0.16, 0.24, 0.32, and 0.40%, resultingin 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. Quadraticeffects of methionine + cystine levels on weight gain and feed:gain ratio, from1 to 21 days old, and on feed intake, weight gain, feed:gain ratio, absoluteweights of carcass and chest and yields of carcass, thighs and drumsticks, from22 to 42 days old , were observed. According to the performance data, the nutritionalrequirements of methionine + cystine for male Ross broilers were estimated in0.96 and 0.89% from 1 to 21 and 22 to 42 days old, respectively.
