EFFECTS OF A ZINC-DEFICIENT DIET ON TISSUE ZINC CONCENTRATIONS IN RABBITS

Young male New Zealand White rabbits given a diet containing 2 ppm of Zn (Zn-deficient diet) ceased to grow after 5 wk. Control rabbits given diets containing 80 or 85 of ppm Zn and experimental animals given 7 ppm of Zn (low-Zn diet) grew normally. The rabbits given the Zn-deficient diet also exhibited alopecia, skin lesions, and frequent pasteurella infections. These conditions were not observed in rabbits fed the other diets. The testes and thymus were smaller in the rabbits fed the Zn-deficient diet than in rabbits fed the control diet. Serum Zn concentrations in rabbits given the low- or Zn-deficient diets reached new lower levels after 2 wk, and these concentrations were maintained for up to 12 wk. The serum Zn concentration was, however, lower in the rabbits fed the Zn-deficient diet (approximately .35-mu-g/ml compared with .8-mu-g/ml for rabbits fed the low-Zn diet and 1.4-mu-g/ml for rabbits fed the control diet). Tissue Zn concentrations generally declined in rabbits fed the low- and Zn-deficient diets, but this response depended on the particular tissue and diet. Zinc levels in bone decreased by approximately 45% and in fur by 20 to 30% on either low-Zn or Zn-deficient treatments. With a Zn-deficient diet, Zn in liver and testes decreased by 20%, Zn in skin by 35%, and Zn in brain by 10%. The Zn concentration in the skeletal muscle and thymus was, however, maintained. In the eye, Zn concentration in the aqueous humor declined by approximately 20% in rabbits fed the Zn-deficient diet. Concentrations in the vitreous humor, lens, and iris-ciliary body were maintained, and a decrease in the retina was not statistically significant. The Zn concentration in the cornea decreased by 30%.