Use of deslorelin acetate to advance ovulation in goats for timed artificial insemination

Abstract

The objective of this study was to determine the efficacy of deslorelin in advancing ovulation for timed artificial insemination (AI) protocols in goats. We hypothesized that deslorelin treatment advances the onset of ovulation and improves AI pregnancy rates. Does were synchronized using a 5-day CIDR (controlled internal drug releasing insert) protocol with prostaglandin treatment at CIDR insertion. For Experiment 1, does received 0.2 mg of intramuscular deslorelin (n = 9) or saline (control, n = 10) at CIDR removal. Serial blood collections and transrectal ultrasonography were performed to assess ovarian dynamics and identify ovulation. For Experiment 2, does received 0.2 mg of intramuscular deslorelin (n = 42), 5 ml of PMSG (pregnant mare serum gonadotropin)/hCG (human chorionic gonadotropin) (n = 42), or were left untreated (control, n = 42) at CIDR removal, and were subsequently bred by transcervical AI with fresh semen after 48 to 56 hours. Pregnancy diagnosis was performed at 50 and 90 days after AI. In Experiment 1, compared to control does, deslorelin-treated does had an increased (p < 0.01) number of ovulations and increased (p < 0.01) serum estradiol concentrations from 48 to 72 hours after CIDR removal. Serum progesterone concentrations did not differ between treatments. In Experiment 2, there was a main effect (p = 0.02) of treatment on pregnancy rates, with control does tending (p = 0.06) to have greater pregnancy rates than those treated with deslorelin or PMSG/hCG. Deslorelin treatment also resulted in decreased (p = 0.04) breeding season pregnancy rates and increased (p = 0.05) number of cycles to achieve pregnancy compared to control does. These results demonstrated that deslorelin not only has a super-ovulatory effect but also, at the dose given, can negatively impact does’ subsequent ovarian function and ability to achieve pregnancy.