Vitamin A Destruction by Nitrite In Vitro and In Vivo

Abstract

In vitro and in vivo studies were conducted to investigate some effects of nitrite on vitamin A destruction in sheep and chickens. The addition of KNO₂ to either abomasum or ventriculus fluid, where pH was below 4, resulted in rapid vitamin A destruction. But in rumen, crop or intestine fluid, where pH was above 6, relatively little vitamin A was destroyed in the presence of KNO₂ during a 60 minute incubation period. When 2.0% of KNO₂ was fed to fistulated sheep no nitrite was found in either rumen or abomasum fluid at approximately 90 minutes after feeding. Furthermore, there was relatively little difference in vitamin A concentration between abomasum fluids collected from sheep receiving the control and nitrite rations, suggesting that dietary nitrite did not enhance vitamin A destruction in the sheep. On the other hand, when broilers were fed 0.74% of KNO₂, nitrite was found in ingestaobtained from the crop, ventriculus and intestine at 2 hours after feeding. In addition, the concentration of vitamin A in both the ventriculus and intestine ingesta obtained from birds receiving KNO₂ was much less than in similar ingesta obtained from control birds. These data suggest that in the presence of nitrite vitamin A is destroyed in the ventriculus area of the digestive tract of the chick, where the pH is approximately 4. Copyright © 1963. American Society of Animal Science . Copyright 1963 by American Society of Animal Science