This study was conducted to evaluate the effects of dietary threonine levels and immune system activation on performance and carcass characteristics of weaning pigs. A total of 360 piglets, 180 males and 180 females, weaned at 20.3 days of age and initial weight of 5.31 ± 1.23kg, were used in a randomized blocks experimental design, in a 5x2 factorial scheme five levels of total threonine (0.85; 0.95; 1.05; 1.15; 1.25%) and two forms of immune system activation (vaccinated and unvaccinated), with four replications and nine animals per experimental unit. There was no interaction between the threonine levels and the degree of activation of the immune system of animals for all parameters evaluated. Threonine levels and immune system activation did not affect the performance of the animals. Threonine levels linearly affected the percentage of water and fat in the carcass and daily deposition of fat. The level of total threonine 0.85%, corresponding to 4.29g daily intake of threonine, and a threonine: lysine ratio of 55%, provide the requirement performance and carcass for piglets from six to 16kg. No harmful effect on animal performance was caused by the activation of the immune system.
amino acids; fat deposition; ideal protein; immunity