Methionine + cystine requirements for meat type quails during the growing phase were evaluated in a completely randomized experimental design with five levels of methionione + cystine (.73, .79, .85, .91, .97, and 1.03%), and five replicates of 13 quails per experimental unit. Body weight (g), weight gain (g), feed intake (g), and feed: weight gain ratio were recorded for each experimental period (from seven to 21 days and seven to 42 days of age). At 42 days of age, four quails (two males and two females) were randomly sampled from each experimental unit, slaughtered after a jejunum of eight hours to evaluate weights and yields of carcass relative to live body weight and yields of main cuts (breast and thigh), edible giblets (liver, gizzard, and heart) and abdominal fat relative to carcass weight (without foot and head). Methionine + cystine levels showed quadratic effects on body weight and weight gain at 21 days of age, with estimated maximum performances for quails fed .95% methionine + cystine level, while feed:weight gain ratio decreased with the increasing level of these amino acids. Significant and linear effects of methionine + cystine on body weight were observed at 42 days of age on weight; and on weight gain and feed intake from seven to 42 days of age. No significant effects of methionine + cystine were observed for live body weight, weights and yields of breast, thigh, abdominal fat, liver, gizzard, and heart. Higher body weight, eviscerated carcass, thigh, breast, abdominal fat, gizzard, and liver weight and yield were observed for females, while males showed higher eviscerated carcass weight. The highest weight gains were observed for EV2 quails fed .95% methionine + cystine from 7th to 21st days of age and from 7th to 42nd days of age corresponding to a methionine + cystine: lysine ratio of .73% and .79% and to a daily methionine + cystine intake of .134 and .234g/quail, respectively.
quail; nutritional requirement; amino acid; performance; total methionine + cystine; carcass yield
