Bio-efficacy of organic selenium compounds in broiler chickens

This study is aimed at comparing the bio-efficacy of different inorganic and organic Se compounds. Three broiler experiments (Exp1 = Ross PM3; Exp2 = Ross 308; and Exp3 = Ross 308) were performed, on the basis of Se tissue accretion, to define the bio-efficacy of Se sources. Birds were fed a control diet (negative control [NC]; no supplemental Se) and, depending on the study, the NC was supplemented with sodium selenite (SS), Se-yeast (35%, 56%, 65% or 72% of Se as selenomethionine (SeMet); SY35, SY56, SY65 and SY72), pure forms of selenocysteine (SeCys) (methylselenocysteine [MSeCys]; L-selenocystine [L-SeCys]), or pure form of organic Se (L-selenomethionine, L-SeMet or hydroxy-selenomethionine, OH-SeMet) at 0.3 mg Se/kg. In Exp 2, an additional treatment of SY65 + L-SeCys was also fed, with both sources added at 0.3 mg Se/kg. In Exp3, L-SeMet and OH-SeMet, were supplemented at 0.15, 0.30, 0.45 and 0.60 mg Se/kg. The results of Exp 1 (mg Se/kg muscle DM) were: NC, 0.56; SS, 0.73; MSeCys, 0.68; L-SeCys, 0.70; SY65, 1.52; OH-SeMet, 1.85 (p