Early Tissue 65 Zn Distribution After Duodenal Dosing in Calves Fed Zinc-Deficient and Control Diets 1 2

Abstract

Summary

Following duodenal dosing, ⁶⁵Zn was rapidly accumulated by several calf tissues, with a considerable amount in the liver and other tissues within 1 hr. With adequate dietary zinc, liver contained a substantial quantity of labile zinc which was greatly depleted in calves fed a zinc-deficient diet for 2 weeks. Other soft tissues had a very limited amount of labile zinc. Zinc turnover rate was much slower in muscle than in the softer tissues, and was not greatly affected by dietary zinc level. Transfer of zinc from the intestinal mucosa to the blood appeared to be the rate-limiting step in zinc absorption. This step was accelerated by feeding a zinc-deficient diet for 2 weeks. However, ⁶⁵Zn uptake by the mucosa from the intestinal contents was vastly increased by the zinc-deficient diet.