Effect of controlled internal drug release device and progesterone sponge on short-term estrus synchronization in Zandi ewes during the breeding season

The aim of this study was to investigate the effect of a controlled internal drug release (CIDR) device and progesterone sponge on the short-term estrus synchronization in Zandi ewes during the breeding season. Sixty Zandi ewes were selected and divided into 3 groups at the beginning of breeding season. The first group was the control group. The second group received insertion of a CIDR device and 1.5 ml of gonadotropin-releasing hormone on day 0, 1.5 ml of natural prostaglandin on day 6, and 2.5 mg of pregnant mare serum gonadotropin with removal of the CIDR device on day 7. In a third group, the same treatment was used, but a medroxyprogesterone acetate-impregnated sponge was inserted instead of the CIDR device. All of the ewes mated naturally. There were significant differences in estrus, fertility, and pregnancy rates between the second group and the control group (P