Hormonal Management for the Induction of Luteolysis and Ovulation in Andalusian Jennies: Effect on Reproductive Performance, Embryo Quality and Recovery Rate

SIMPLE SUMMARY: Embryo transfer is of utmost importance in endangered species such as donkeys. To maximize the number of embryos obtained and, thus, the number of foals born, the manipulation of cycles (shortening of interval between cycles and timely ovulation induction) is crucial. Therefore, the aim of this study was to compare two prostaglandins (luprostiol, LUP, and dinoprost, DIN) and two ovulation-inducing agents (human Chorionic Gonadotropin, hCG, and deslorelin, DES) in 26 fertile embryo donor jennies. In Experiment 1, jennies were randomly treated with either LUP or DIN after recovering the embryos. In Experiment 2, the jennies were treated with either hCG or DES to synchronize ovulation and breeding. Both prostaglandins shortened the cycles similarly and did not affect the embryos recovered. Although the ovulation inductors reported similar results, DES induced ovulation more rapidly. Interestingly, the embryo quality was lower when the uterus showed high edema at the time of insemination. ABSTRACT: Two prostanglandins (luprostiol, LUP, and dinoprost, DIN) and two ovulation-inducing agents (human Chorionic Gonadotropin, hCG, and deslorelin, DES) were evaluated for luteolysis and estrus induction, and for ovulation induction, respectively, in embryo donor jennies. Twenty-six fertile Andalusian jennies were used. In Experiment 1, jennies (n = 112 cycles) were randomly treated with either LUP or DIN after embryo flushing. In Experiment 2, donors (n = 84 cycles) were randomly treated with either hCG or DES to induce ovulation. No differences were found between prostaglandins for all variables studied (prostaglandin–ovulation interval (POI), interovulatory interval (IOI), embryo recovery rate (ERR), positive flushing rate (PFR) and embryo grade (EG)). The ovulation rate was similar for hCG and DES (60.9% vs. 78.7%). However, the interval to ovulation (ITO) was affected (62.61 ± 7.20 vs. 48.79 ± 2.69 h). None of the other variables studied (ERR, PFR and EG) were affected (p > 0.05), except for embryo quality (p = 0.009). In short, both prostaglandins evaluated are adequate to induce luteolysis and estrus. Both ovulation-inducing agents hastened ovulation, but DES seems to be more effective than hCG. Follicular diameter affected the interval from treatment to ovulation, and high uterine edema was related to low embryo quality.