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Effects of Zinc Deficiency in the Diets of Hens¹

Department of Poultry and Department of Biochemistry, University of Wisconsin, Madison, Wisconsin

Two experiments, conducted with White Leghorn hens housed to exclude zinc from the environment and fed semipurified diets, led to the following conclusions:

1. Young hens receiving isolated soy protein-type diets (10 ppm of zinc) failed to gain normally unless the diet contained the higher levels of calcium (4.0%) and zinc (65 ppm) simultaneously. Unless supplemented with zinc, neither normalcalcium (2.25%) nor high-calcium (4.0%) isolated soy protein-type diets permitted normal egg production or hatchability. The chicks and developing embryos showed marked effects of zinc deficiency.

2. Increasing the zinc content of an isolated soybean protein-sucrose diet containing 4.0% of calcium from 10 to 18 ppm of zinc enabled hens to produce normal chicks.

3. Increasing the dietary calcium level of an isolated soybean protein-sucrose ration from 2.25% to 4% of the diet for hens potentiated the zinc deficiency in the developing chick.

4. The excess calcium appeared to decrease the blood plasma zinc concentration in the hens, but did not alter the red blood cell zinc content.

5. Blood hemoglobin levels of hens were not affected, but hemoglobin levels of zincdeficient day-old chicks hatched from eggs laid by these hens were significantly (P < 0.05) lowered by increasing calcium in maternal diet.

6. Zinc-deficient chicks sometimes hatched, but were weak and would not stand, eat or drink. These chicks had an accelerated respiratory rate and showed labored breathing. These symptoms were aggravated by disturbance of the chicks and usually were fatal. Retarded feathering and frizzled feathers were observed. Repeated injections of zinc chloride greatly benefited such chicks, but chicks showed limited tolerance to such injections.

7. Embryonic development of chicken embryos was altered by withholding zinc from the maternal diet. The major defect was grossly impaired skeletal development.

8. Hens receiving small quantities of zinc in the diet deposited less zinc in the yolk than similar birds receiving supplemental zinc in otherwise identical diets.

9. Supplementation of maternal diet with 55 ppm of zinc as zinc carbonate prevented all abnormal embryonic development.

² Present address: Department of Poultry, South Carolina Experiment Station, Clemson, South Carolina.

Manuscript received 26 May 1961.