Effect of Alterations of Zinc Status on the Zinc Content of the Gastrointestinal Tract of Chicks

The zinc content of intestinal tissue of growing chicks depends upon the anatomical site of sampling, the dietary intake of zinc, and the extent of fasting. The zinc content of duodenum, but not ileum, increased after 24 hr fasting in both zinc-deficient and zinc-adequate chicks and rapidly decreased to prefasting levels after refeeding. Feeding diets either adequate or greater than adequate in zinc to zinc-deficient chicks resulted in a rapid increase in plasma, duodenal, and ileal zinc contents to levels found in animals maintained continuously on these diets. The zinc content of tibia rose more slowly over this same time period. Thus, duodenal zinc content accurately reflects acute increases in “available” body zinc and most likely represents zinc being excreted endogenously from the body tissues.