The Effect of Diet on the Comparative Activities of Pyridoxal, Pyridoxamine and Pyridoxine for Chicks

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Abstract
Pyridoxal and pyridoxamine are less active than pyridoxine in supporting chick growth on otherwise complete rations containing large amounts (61%) of glucose or sucrose. The three compounds are equally active when autoclaved starch is the dietary carbohydrate. The latter type of ration simulates most closely those used in practical nutrition. The comparative activities of the three compounds on these rations is unchanged by feeding aureomycin at a level of 25 mg per kilogram of diet. Substantial increases in growth with diets suboptimal in vitamin B6 resulted when 20% of lactose was added to diets based on glucose or sucrose. No such increase resulted from addition of lactose to the starch-containing diet. The comparative activities of the three forms of vitamin B6 are not changed by addition of this amount of lactose to any of these diets. Possible explanations for the observed differences in activity of pyridoxal, pyridoxamine and pyridoxine with the composition of the ration are considered. The results are consistent with known changes in composition of the intestinal flora, and indicate that competition of intestinal flora with the host for limited supplies of these nutrients may explain the differences in relative activities of these compounds that occur with differences in the diet or mode of administration.