Induction of ovulation in rabbits with pure urinary luteinizing hormone and human chorionic gonadotrophin: comparison of oocyte and embryo quality.

Thirty-six 18-week-old nulliparous does were stimulated with a single dose of 25 IU pregnant mare serum gonadotrophin (PMSG). Ovulation was induced 48 h later with 50 IU luteinizing hormone (LH) (18 does) or 50 IU human chorionic gonadotrophin (HCG) (18 does) in order to determine the effects of pure urinary LH and HCG on the quality of oocytes and embryos. Nine does were mated in each group. The does were slaughtered 24 h after induction of ovulation to recover oocytes and 48 h after mating to recover embryos. The number of haemorrhagic, preovulatory and luteinizing follicles per ovary were recorded. The quality of oocytes and embryos recovered were evaluated. No significant differences in the number of haemorrhagic follicles (blood follicles without stigma), preovulatory and luteinizing follicles were observed between LH and HCG groups. LH has a selective action, which could permit the acquisition of better quality oocytes. Although the fertilization rate was similar in both groups (LH versus HCG), the percentage of degenerate embryos (grade 5) was lower for the LH (3%) than the HCG (13%) groups.