Pregnancy Rate in Ewes Injected with Zinc Oxide during an Estrus Synchronization Protocol

Objective: To measure the effect of zinc injection, during an estrus synchronization protocol, on pregnancy rate in sheep from Valle de Mexicali.Design/Methodology/Approach: The experimental units were 157 ewes, which were allocated in five farms (F): F1 (n19), F2 (n27), F3 (n20), F4 (n71), and F5 (n21). In each farm, the ewes were randomly assigned to one of three treatments: control, z-100 and z-200. The ewes from control groups were subcutaneously injected with 4 mL of olive oil as placebo. The ewes from groups z-100 and z-200 were subcutaneously injected with 100 and 200 mg of zinc oxide. The response variables were the preovulatory diameter of the largest follicle and pregnancy rate. Results: The differences between experimental groups in diameter of the largest preovulatory follicle and pregnancy rates were not significant (p0.05).Study Limitations/Implications: The ewe’s reproductive response to zinc injection might be affected by the animal mineral status, it is recommended to carry on supplementation based on mineral blood concentrations. Findings/Conclusions: The subcutaneous injection with 100 or 200 mg of zinc oxide did not affect the size of the largest preovulatory follicle and pregnancy rate in ewes.