Relative bioavailability in chicks of manganese from manganese propionate

The relative bioavailability (RB) of Mn propionate, as compared with feed-grade Mn sulfate, was determined in chicks fed a corn- and soybean meal-based diet for 14 d. Diets were supplemented with 0, 20, 100, and 500 mg of Mn/kg of diet and assessed for growth, intake, and FE. Levels of Ca and P were also increased in this diet compared with a typical production diet to see whether, when chicks were challenged with antagonists, a difference existed between inorganic Mn sulfate and organic Mn propionate. No differences were observed for any growth parameters for either mineral level or dietary source. Relative bioavailability was determined using Mn concentration in bone, assuming a value of 100% from the feed-grade Mn sulfate. The RB of Mn propionate was 139% compared with Mn sulfate when using the relative slope assay. We concluded that organic Mn propionate has an improved RB compared with the commonly used inorganic feed-grade Mn sulfate in the presence of high dietary Ca and P.