Availability of Niacin in Corn and Milo for Swine

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Abstract
Three experiments were conducted with 46 crossbred barrows to determine the availability of niacin in yellow corn and milo for growing pigs. Urinary excretion of free niacin, N'-methylnicotinamide (NMN), N'-methyl-2-pyridone-5-carboxamide (2 PY), digestibility of niacin, blood levels of diphosphopyridine nucleotide (DPN), rate of gain, feed conversion and digestibility and retention of nitrogen were used as criteria for determining availability. In the first experiment, average daily gains and NMN excretion were increased significantly (P<.01), by the addition of 17.6 mg. of niacin per kg. of feed to a corn ration. In the second experiment, average daily gains were similar for pigs fed 40, 60 or 80% corn ration without added niacin. Gains were increased by the addition of 8.1 mg. of crystalline niacin per kg. of feed to the 80% corn ration. NMN excretion increased in a linear manner for pigs fed the 40, 60 and 80% corn rations and the 80% corn ration with added niacin. In the third experiment, average daily gains, NMN and 2 PY excretions and blood DPN levels were increased by the addition of 33.0 mg. of niacin per kg. to an 80% milo ration. Differences observed in NMN excretion were significant (P<.025). Generally only slight differences were noted in free niacin excretion, nitrogen retention and digestibility and feed conversion. The results indicate that the niacin of corn and milo is largely unavailable to swine. Copyright © 1967. American Society of Animal Science . Copyright 1967 by American Society of Animal Science