Reproductive fecundity of Iraqi Awassi ewes immunized against synthetic inhibin-α subunit or steroid-free bovine follicular fluid

Objective: The present study was conducted to investigate the impacts of active and passive immunization against synthetic inhibin and steroid-free bovine follicular fluid, respectively, on reproductive fecundity out of breeding season in Iraqi Awassi ewes. Methods: Follicular fluid was aspired from mature bovine follicles, treated with activated charcoal, and used for immunization of male rabbits for obtaining steroid free bovine follicular fluid (SFBFF) antiserum. Forty non-pregnant Awassi ewes were allocated into 4 groups (n = 10 each). At day 38 of experiment, ewes were treated with intra-vaginal MPA sponge (60 mg for 12 days). At days 0, 28, and 50, ewes were treated with 4, 2, and 2 mL of normal saline (control; C-ve), 400, 200, and $200{\mu}g$ of ovalbumin (C+ve), 400, 200 and $200{\mu}g$ of inhibin (SI group), respectively, and 4 mL of normal saline at day 0, and 4 and 2 mL of SFBFF antiserum at days 28 and 50, respectively, (AI group). After mating with Awassi rams, pregnancy and embryo number were diagnosed, at day 38 of pregnancy, using ultrasonography. Blood samples were collected at days 30, 60, 90, and 120 of pregnancy, for assessment of estradiol-$17{\beta}$ (E2) and progesterone (P4) levels. After parturition, numbers of delivered lambs were recorded. Results: The results revealed significant increase of P4 and significant decrease of E2 levels in SI and AI pregnant ewes than controls at days 30, 60, 90, and 120. Newborn number increased significantly in SI and AI treated than control ewes. Conclusion: Active or passive immunization against endogenous inhibin could augment reproductive fecundity out of breeding season in Iraqi Awassi ewes.