Effect of Gossypol on the Removal of Nitrogen and Amino Acids from Feed in Digestion by the Rat

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Abstract
The effect of bound gossypol on the nitrogen economy of the rat was studied by using either glandless cottonseed meal or the same meal to which gossypol was bound as the sole source of dietary protein for the determination of nitrogen balance and Thomas-Mitchell biological values. The amino acid composition of the small intestinal chyme, 1 hr after feeding, also was determined for these two diets with rats trained to consume their daily ration as a single meal. Over the 1-week period there was no significant difference in the nitrogen balance or the biological value of the two diets. However, when the component parts of the biological value expression were examined separately, the value for fecal nitrogen less metabolic fecal nitrogen was significantly higher for rats fed the gossypol-containing diet. The converse was true for the urine nitrogen less the endogenous urinary nitrogen, a result which, when combined with the fecal values in the biological value expression, produced no net differences in the biological values. The amino acid analysis of the partially digested chyme indicated that all analyzed amino acids were present in chyme of the proximal gut of rats fed a diet containing gossypol to a significantly greater degree than the amounts present on the non-gossypol treatment. The same was true in the distal gut with the exception of glycine which showed no difference. No specific group of amino acids could be shown to have an altered pattern of amino acid uptake in the gossypol treatment. Increased ingesta passage rate, inhibition of digestive enzyme action, and inhibition of amino acid transport by gossypol could all account for the observed results and could not be distinguished separately in this study. Copyright © 1977. American Society of Animal Science . Copyright 1977 by American Society of Animal Science.