Availability of Niacin in Wheat for Swine

Abstract

An experiment was conducted with 24 barrows to determine the availability of niacin in wheat for swine. Urinary excretion of N′-methylnicotinamide (NMN), N′-methyl-2-pyridone-5-carboxamide (2PY) blood levels of diphosphopyridine nucleotide (DPN), rate of gain, feed conversion and digestibility and retention of nitrogen were used as criteria for determining availability. Average daily gains and feed intake were higher (P < 0.05) for the pigs fed the 80% wheat ration (no supplemental niacin) than those fed 40%, or 40% (high niacin) wheat rations. No significant differences were noted in feed required per kilogram of gain. Urinary NMN and 2PY excretion increased in a linear manner (P < 0.005) for the pigs fed the 80, 40 and 40% (high niacin) rations, respectively. Blood DPN levels were lower (P < 0.05) for the pigs fed the 80% wheat ration than for those fed the 40% wheat rations. Nitrogen digestibility was lower (P < 0.01) for the pigs fed the 80% wheat ration than for those fed the 40% wheat rations. No significant differences were noted in nitrogen retention. The results from the excretion patterns of NMN and 2PY and the blood DPN levels observed indicate that the niacin of wheat is not appreciably available to swine.