RESUMO
These studies were designed to determine the relative bioavailability and tolerance of tribasic Mn chloride (TBMC) for growing broiler chickens. In experiment 1, birds were fed a basal diet (starter, 102 ppm; grower, 209 ppm) or the basal diet supplemented with 3,600, 4,500, or 5,400 ppm Mn from either TBMC or manganese sulfate (MnSO(4)), and BW, feed intake, and plasma Mn were measured. In experiments 2 and 3, diets included the basal diet (45 and 43 ppm Mn, respectively) and the basal diet supplemented with graded levels of either TBMC or MnSO(4) ranging from 30 to 240 ppm Mn. Body weight and feed intake were measured and tibia, bile, and liver were collected for mineral analysis; heart samples were taken for manganese superoxide dismutase activity, protein, and relative mRNA abundance. In experiment 1, BW differed among treatments, with higher Mn leading to lower BW (P < 0.05). Birds from all treatments showed higher plasma Mn than birds fed the basal diet. Birds supplemented with the highest level of MnSO(4) had the highest level of plasma Mn (P < 0.05). In experiment 2, tibia and liver Mn increased with higher dietary Mn regardless of source (P < 0.05). Liver Mn increased up to the 60 ppm diets whereas Mn in the tibia was highest with the 130 ppm diets. Bile Mn increased with increasing dietary Mn, but these differences were not significant. In experiment 3, manganese superoxide dismutase activity, protein, and relative mRNA abundance were not affected by diet. The calculated bioavailabilities of TBMC and MnSO(4) did not differ significantly (P > 0.20). Together, these results indicate that TBMC is as effective as and better tolerated than MnSO(4) and that supplementing Mn at the lowest level used in this study may be sufficient for normal development of broiler chickens.
