TOXICITY OF ZINC TO PREGNANT SHEEP

The effects on pregnant sheep of cadmium and excess dietary zinc, separately and in combination, were investigated. Zinc induced severe copper deficiency in the ewes and caused a high incidence of abortions and stillbirths. Feed consumption, weight gain, and efficiency of feed utilization were all reduced in sheep receiving 750 mg Zn/kg diet. Supplementary copper prevented the development of copper deficiency but failed to prevent the adverse effect of high zinc on weight gain, feed consumption, efficiency of feed utilization, and lamb viability. The possible mechanisms involved in these effects are discussed. No adverse effect on reproductive performance resulted from the inclusion of 3 mg Cd/kg diet. © 1979.