RELATIVE BIOAVAILABILITY OF MANGANESE FROM A MANGANESE-METHIONINE COMPLEX AND INORGANIC SOURCES FOR RUMINANTS

Two experiments were conducted to study the relative bioavailability of Mn from a feed grade Mn-Met complex or from two feed grade MnO sources using reagent grade MnSO4.H2O as the standard. In each experiment, 42 crossbred wether lambs were fed one of seven dietary tratments for 21 d and then killed; liver, kidneys, and right metacarpus were removed for MN analysis. In Experiment1, treatment included the basal diets (34.4 ppm of Mn, DM basis) alone or supplemented with 900, 1800, or 2700 ppm of Mn as reagent grade MnSO4.H2O or feed grade Mn-Met complex. In Experiment 2, the basal diet (31.5 ppm of Mn, DM basis) was fed alone or was supplemented with 900, 1800, or 2700 ppm of Mn as reagent grade MnSO4.H2O or 1800 ppm of Mn as feed grade Mn-Met, feed grade MnO A, or feed grade MnO B. The overall estimated relative bioavailabilities based on multiple linear regression coefficients of bone, kidney, and log-transformed liver Mn concentrations on total dietary Mn concentrations were 100, 121, 70, and 53% for MnSO4.H2O, Mn-Met complex, MnO A, and MnO B, respectively.