Two studies were conducted to determine the true digestible threonine requirement for barrows from 15 to 30 kg live weight (LW). In the first (digestibility trial) were used eight barrows, averaging 30,3 kg LW initial weight, submitted previous to the ileum-rectal anastomosis surgery, were allotted to a randomized block design, with two treatments, four replicates and one animal per experimental unit. The treatments consisted of a basal diet, with 15.7% of crude protein (CP) and .49% of total threonine, and one a protein free diet, to determine the coefficient of true ileal digestibility of threonine in the basal diet. In the second experiment, 40 crossbred pigs, barrows, averaging 15.3 kg initial weight were allotted to a randomized block design, with five treatments (.49, .54, .59, .64, e .69% of total threonine), four replicates and two animals per experimental unit. Using performance traits and serum urea level and applying the quadratic and/or the broken line models, a requirement value of .63% total threonine for 15 to 30 kg barrows was obtained . Considering the threonine basal diet coefficient of true ileal digestibility (84.6%) and the supplemented crystalline threonine digestibility coefficient of 100%, a requirement value of .56% true digestible threonine was obtained.
amino acids; digestible threonine requirement; ileal digestibility; barrows
