Bioassay Determination of the Biotin Content of Corn, Barley, Sorghum and Wheat

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Abstract
Crossbred female chicks were used to ascertain the quantity of biologically available biotin in corn, wheat, barley and sorghum. From day 1 to day 14 posthatching, chicks were fed a bio tin-free pre-test diet containing .5% sulfathiazole and lyophilized raw egg white. Test diets included the various feedstuffs which were finely ground and incorporated (at the expense of cornstarch) into a purified bio tin-free amino acid diet at a level of 20%. A biotin standard curve was generated using biotin levels of 0, .01, .02, .04 and .06 mg/kg diet. Weight gain and hepatic pyruvate carboxylase activity (µmole 14 CO2 fixed/min/g liver) were principal response criteria. Corn and barley were also fed in the presence of crystalline avidin (3.81 mg/kg diet). Avidin eliminated the growth response, indicating the measured responses were, in fact, due to the biotin furnished by these grains and not due to other extraneous factors present therein. Using standard curve methodology, estimates of available biotin were .108 mg/ kg for corn, .082 for barley, .092 for sorghum and .043 for wheat.