Assessment of the Availability of Niacin in Corn, Soybeans and Soybean Meal

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Abstract
Three trials, involving 640 female and 70 male 8-day-old crossbred chicks, were used to investigate the value of supplementing a corn-soybeam meal starter diet with synthetic niacin and to determine the biological availability of the niacin in yellow corn (non-roasted or roasted to 160 C), solvent-extracted soybean meals (SBM), and raw and autoclaved full-fat soybeans. No positive response from supplementation of the starter diet with 2,4, 8 and 27 ppm of synthetic niacin was evident. Using a niacin-free purified amino acid diet and the standard curve and slope-ratio techniques, availability of niacin to the chick from non-roasted and roasted corns was about 30%, from processed soybean, 100%. Conversion ratio of soybean tryptophan to niacin in the chick was estimated to be between 50 and 70 to 1. Estimated available nicotinamide equivalent (niacin activity) was 8.2, 5.7, 8.6, 113.0, 132.5, 25.1 and 104.3 ppm, respectively, for non-roasted corn, 120 C corn, 160 C corn, 44% C.P. SBM, 49% C.P. dehulled SBM, raw and autoclaved full-fat soybeans.