Absorption, Excretion, and Retention of Orally Administered Zinc-65 in Various Tissues of Zinc-deficient and Normal Goats and Calves

Abstract

Absorption, excretion and tissue distribution of ⁶⁵Zn was determined following oral dosing in zinc-deficient and normal calves and goats. In the livers, level of ⁶⁵Zn was higher at 2 days than at later times. In some tissues, including hair, bone and muscle, the ⁶⁵Zn concentration increased with time while in others the level reached a peak between 2 and 28 days after oral dosing. The tissues of the zinc-deficient animals held the ⁶⁵Zn more tenaciously than those of the control animals. Fecal excretion of ⁶⁵Zn reached a peak the third day after dosing and declined thereafter. ⁶⁵Zn excretion via feces was higher for control than zinc-deficient animals. Apparent absorption was very high exceeding 80% for some treatments. These high absorption values are attributed to several factors including semipurified diets containing very low levels of zinc and are a reflection of mechanisms resulting in homeostatic conservation of the zinc.