Manganese bioavailability in a MN-methionine chelate

Abstract Two experiments were conducted to assess the bioavailability of both managanese (Mn) and methionine (MET) in a Mn-MET chelate (Mn-MET). In the first experiment, Hubbard female chicks were fed graded levels of Mn as either Mn-MET or feedgrade MnO in both the presence and absence of phytate and fiber derived from a corn-soybean meal mixture (C-SBM). Bioavailability of Mn was determined by assessing Mn-uptake by tibia from chicks fed graded levels of Mn-MET relative to those fed graded levels of MnO by use of multiple regression slope-ratio methodology. Mn deposition in tibia per unit of supplemental Mn consumed was much greater in chicks fed the fiber- and phytate-free casein-dextrose diet than in those fed this same diet with a 10% addition of C-SBM. When either Mn concentration in bone, or total Mn in bone, was regressed on supplemental Mn intake, Mn-MET was found to provide 30.1% (basal diet) and 74.4% (basal+10% C-SBM) more bioavailable Mn than that provided by MnO. Although total bone Mn as well as bone Mn concentration regressed on Mn intake yielded similar results for Mn bioavailability, total bone Mn provided better regression fits (i.e., R 2 ) and thus a more precise basis for statistical discrimination between slopes obtained with the standard (MnO) and the test (Mn-MET) compounds. In the second experiment chicks were fed graded levels of either MET or Mn-MET for 9 days. Weight gain was recorded and bioavailability of MET determined by comparing regressions of gain on Mn-MET intake to that of gain on MET intake. Bioavailability of MET in Mn-MET was found to be 68%.