Selenium supplementation can improve the immune system by acting on the antioxidant control and modulation of redox cell homeostasis, becoming an alternative to the use of growth promoters in piglet nutrition. The objective of this study was to evaluate the effect of supplementation with or without complex sources on organic selenium molecules, as well as the level of supplementation in the diet of weanling piglets. Forty weaned piglets at 28 days of the same commercial strain were used, with initial average weight of 6.60 ± 1.06 kg, distributed in a randomized block design (DBC) and evaluated in three phases (I - 28 35 days of age II - from 36 to 45 days of age III - from 46 to 60 days of age). The experimental diets consisted of: Control ...