This study was carried out to evaluate the requirements of digestible threonine in diets of gilts from 15 to 30kg, maintained in thermoneutral environment. Seventy crossbreed gilts with an initial weight of 15.1 ± 0.4 kg were used in a randomized blocks design, with five treatments (levels of digestible threonine), seven replicates and two animals per experimental unity. The treatments corresponded to the levels of 0.54, 0.58, 0.61, 0.65, e 0.698% of digestible threonine. Digestible threonine levels in the diet increased the daily weight gain in a quadratic way up to the level of 0.61% and the feed:gain ratio up to the level of 0.62%. Protein and fat deposition rates also increased in a quadratic way reaching maximum value up to the level of 0.61%. A linear effect of the treatments was evidenced on the absolute and relative weights of the intestine. The calculated level of 0.62% of digestible threonine corresponding to a relation with digestible lysine of 67% and a daily intake of 7.11 g, provided better performance of gilts maintained in a thermoneutral environment from 15 to 30 kg.
environmental temperature; digestible threonine; digestible lysine ratio; performance
