Ovine endometrial estrogen receptor expression is altered following PG-600 administration.

Background: Dysregulation of the estrogen receptor 1 (ESR1) expression during the establishment of pregnancy could contribute to reduce fertility reported in ewes treated with PG-600.

Objectives: The objective of this study was to evaluate the effect of treatment with PG-600 on ESR1 expression in the ovine endometrium during early diestrus.

Methods: Polypay ewes (n = 24) that had exhibited an oestrous cycle of normal duration (16-18 days) were treated with intravaginal progesterone-releasing device (CIDR) for 9 days.

Estrus Synchronization in the Sheep and Goat.

Estrus synchronization and manipulation are a tool that has been used by producers to provide uniform lamb and kid meat production and dairy sheep and goat milk production, to concentrate work and labor cost, and to plan for the lambing and kidding time. Breeders can also use estrus synchronization to stimulate ewes and does to exhibit estrus and ovulate outside of the breeding season, although both the ovulation rate and pregnancy rate may be decreased. To increase the ovulation rate outside of the breeding season, a variety of estrus synchronization methods have been used.

Effect of different dosages of PG-600 on ovulation and pregnancy rates in ewes during the breeding season.

This study compared the reproductive effects of different dosages of PG-600 (Intervet/Merck Animal Health, Madison, NJ) during the breeding season of ewes. PG-600 is a single-dose injectable product labeled for estrous induction in swine, containing equine chorionic gonadotropin (80 IU/mL) and human chorionic gonadotropin (40 IU/mL). PG-600 is routinely used off-label for out-of-season estrous induction in sheep.