Extracellular zinc concentration and water metabolism in chicks.

Four experiments were performed to determine the effect of dietary zinc deficiency on water metabolism. Day-old chicks were fed for 3 weeks diets which contained isolated soybean protein, cornstarch and graded levels of zinc. Chicks fed the basal (less than 1 ppm Zn) diet supplemented with 0, 5, 10, 20 and 100 ppm zinc had plasma zinc concentrations of 0.2, 0.4, 0.6, 1.0 and 1.3 ppm and hematocrit values of 39, 36, 33, 30 and 29, respectively. Plasma zinc concentration dropped significantly within 12 hours after chicks consumed a zinc-deficient diet and the hematocrit rose significantly within 5 days. Zinc-deficient chicks had significantly (P less than 0.05) less extracellular and more intracellular water than feed-restricted controls. There was no difference in total body water. Zinc-deficient chicks had significantly elevated ratios of Na+/K+ in liver, skin and muscle but no difference in serum. Treatment with a combination of zinc and saline significantly lowered the hematocrit within 2 hours when given intraperitoneally and within 4 hours when given intragastrically. The correlation between the plasma zinc concentration and water distribution suggests that extracellular zinc has a specific effect on water metabolism.