Threonine:lysine ratio for Japanese quail hen diets

The objective of this study was to evaluate threonine requirements for laying Japanese quail fed with different threonine: lysine ratios through measurement of zootechnical and histological performance. a total of 288 Japanese quail at 125 d of age were distributed in a totally randomized design, with 6 treatments and 6 replications of 8 each. the treatments consisted of a basal diet made of corn, soybean meal, and corn gluten meal, supplemented with L-lysine, DL-methionine, L-tryptophan, L-isoleucine, and L-valine to meet the laying Japanese quail essential amino acid needs, except for threonine. the basal diet was supplemented with 0.00, 0.04, 0.08, 0.12, 0.16, and 0.20% of L-threonine in substitution for L-glutamate acid, with the objective of reaching levels of 0.66, 0.70, 0.74, 0.78, 0.82, and 0.86% of threonine in the feed, resulting in threonine: lysine ratios of 66, 70, 74, 78, 82, and 86%. Zootechnical and histological indexes of the digestive and reproductive system were evaluated. the amino acid ratio alteration assessed in this study influenced performance and histology of the quail through improving productive performance at a 78% threonine:lysine ratio.