Optimum dietary standardized ileal digestible isoleucine to lysine ratio for meat-type quails in the growing-finishing phase

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 meattype quails (Coturnix coturnix coturnix) were randomly assigned into five treatments, with seven replicates of 10 quails each. An isoleucinedeficient 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 oneway 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%.