ABSTRACT This study was conducted to determine the optimum standardized ileal digestible isoleucine to lysine (SID Ile:Lys) ratio for meat-type quails from 15 to 35 d of age. Three hundred fifty not-sexed meat-type quails (Coturnix coturnix coturnix) were randomly assigned into five treatments, with seven replicates of 10 quails each. An isoleucine-deficient corn-soybean meal-based diet was formulated and graded supplemented with L-isoleucine (99%) to obtain diets containing SID Ile:Lys ratios of 55,61, 67, 73, and 79%. Data were analyzed as one-way ANOVA and optimum SID Ile:Lys was estimated by polynomial (linear and quadratic) regression. Statistical differences were considered when p<0.05. Quail performance from 15 and 21 d and 15 and 28 d of age was not affected by the treatments. From 15 to 35 d of age, body weight gain and body weight exhibited a quadratic response to increasing dietary SID Ile:Lys ratios, and were optimized at 66 and 67% SID Ile:Lys, respectively. Feed conversion ratio was not influenced by SID Ile:Lys ratios in any of the phases assessed herein. Based on the results, the optimum SID Ile:Lys ratio for meat-type quails from 15 to 35 d of age is 67%.

ABSTRACT This study was conducted to estimate the dig. valine to lysine (Val:Lys) ideal ratio for meat-type quails from 15 to 35 d of age. A total of 385, 15-day-old not sexed quails, were randomly assigned to five treatments, each one seven times replicated with eleven quails per experimental unit. Experimental treatments consisted of five dig. Val:Lys ratios (0.65; 0.70; 0.75; 0.80 and 0.85). Ideal dig. Val:Lys ratio was estimated using polynomial regression and linear broken-line regression model. Significant effect was considered when p≤0.05. Feed conversion ratio was not affected by dig. Val:Lys ratios in any of the assessed phases. From 15 to 21 d of age Val:Lys ratios increased linearly feed intake, weight gain and body weight. From 15 to 28 d of age, weight gain and body weight were both optimized by the Val:Lys ratio of 0.77. A linear effect of dig. Val:Lys ratios was observed on weight gain and final body weight from 15 to 35 d of age. From 15 to 35 d of age, according to linear broken-line regression model, the dig. Val:Lys ideal ratios for optimum final body weight and weight gain were 0.77 and 0.76, respectively. Based on the results the estimated dig. Val:Lys ratio for optimum meat-type quail performance from 15 to 35 d of age is 0.77