Effect of dietary zinc on metabolism of zinc 65 in hens

Abstract

Hens fed zinc-deficient (10 ppm Zn) and zinc-supplemented (70 ppm) diets for 5 months were given zinc 65 intramuscularly, and fecal and egg radioactivity was followed for 70 days before the hens were sacrificed. Egg yolks accounted for nearly all of the total egg radioactivity. The low-zinc diet reduced fecal isotope loss to 60% of that observed for the high-zinc diet Fecal and egg-yolk excretion patterns of zinc 65 suggested that the pool of rapidly turning-over zinc which is the precursor for egg and fecal zinc was smaller and had a shorter turnover time in the zinc-deficient hens However, the size of the total body zinc pool was little affected by diet At 70 days after injection, zinc-deficient hens had about 30% as much radioactivity per unit of bone but about 150% as much radioactivity per unit of soft tissue as did the zinc-supplemented hens. These differences in zinc 65 distribution were of the same magnitude when expressed as counts per minute per milligram zinc.