Superovulation in sheep during seasonal anestrus with eCG and anti-eCG

Abstract

Eighteen Corriedale seasonal anestrous ewes were treated with intravaginal progestagen pessaries (60 mg MAP) and 1200 Iu of equine chorionic gonadotropin (eCG or PMSG) 48 hs before pessary withdrawal (PW). Nine ewes (S group) received an injection of ovine eCG antiserum 12 hs after PW. The other nine remained as control group (eCG). Six or seven days after PW, the ovaries were exposed by laparotomy and number of corpora lutea (CL) andanovulatory follicles (>6mm; LAF) were counted. Injection of anti-eCG cause a significant reduction in LAF (5.6 ± 2.6 and O. 7 ± 0.5, for C group and S group respectively, p< 0.5). Ovulation rate was not significantly affected by the treatment (5 ± 1.5 and 3 ± 0.6; for group C and group S respectively). We conclude that it is possible to induce superovulation during seasonal anestrous using this technic. Furthermore, we conclude that the use of eCG antiserum has a benefical effect in controlling ovarian overstimulation.