Practical protocols for timed artificial insemination of jennies using cooled or frozen donkey semen.

BACKGROUND: With the expansion of the donkey industry, timed artificial insemination (TAI) is becoming increasingly important in the reproductive management of jennies, however, TAI has not been widely investigated in donkeys. OBJECTIVES: To develop efficient TAI protocols for cooled or frozen semen in jennies, based around ovulation induction with a GnRH analogue. STUDY DESIGN: Experimental exploratory study. METHODS AND RESULTS: In experiment 1, the effects of different GnRH analogue (deslorelin) doses, follicle diameter (FD) at induction, repeated use of a GnRH analogue, and the influence of season on induction efficiency, as well as distribution of ovulations over time after induction were investigated. Induction efficiency was sufficient with 2.2 mg deslorelin (≥90% ovulation within 48 hours of treatment). Ovulation rate between 24 and 48 hours was highest when the FD at treatment was 31-35 mm, as compared to 25-30 mm or 36-40 mm. Repeated use of deslorelin or treatment during different seasons had no effect on induction efficiency. About 70% of ovulations occurred between 32 and 48 hours, and highest incidence of ovulation was at 36-38 hours after induction. In experiment 2, TAI using cooled semen (1 × 109 motile sperm in a 10 mL volume) was performed once at 8 hours after induction (n = 59). Pregnancy rate after TAI with cooled semen was 49.2% (29/59). In experiment 3, jennies were inseminated twice with 10 (n = 23), 5 (n = 31), 3 (n = 32), 2 (n = 82) and 1 (n = 66) straws (more than 50 × 106 motile spermatozoa in each 0.5 mL straw) of frozen semen at 34 and 42 hours after induction. The pregnancy rates were 30.4%, 35.5%, 34.4%, 29.3% and 28.8%, respectively (P > 0.05). MAIN LIMITATIONS: In the frozen semen trial, 22.5% (68/302) jennies were excluded after failure to ovulate during the appropriate time interval. In addition, there were no control groups for the AI trials. CONCLUSION: When FD reaches 31-35 mm, a donkey jenny can be inseminated once using cooled semen at 8 hours or twice using frozen semen at 34 and 42 hours after deslorelin treatment. The frozen semen TAI protocol resulted in acceptable pregnancy rates using 1 × 108 motile spermatozoa per cycle.

Effect of the Interval From Prostaglandin F2alpha Treatment to Ovulation on Reproductive Efficiency Rates in a Commercial Equine Embryo Transfer Program.

In the present study, 2.228 cycles of 180 Polo Argentino donor mares from an embryo transfer program in Argentina were examined to evaluate the effects of: (1) Interval from Prostaglandin F2alpha analog treatment to ovulation (ITO) on embryo recovery rate (ERR); (2) ITO on number of embryos per flushing (EPF); (3) ITO on multiple ovulation (MO) rate; (4) ITO from donor mare on pregnancy rate (PR) in recipient mares. Mares were inseminated with fresh semen from 31 fertile stallions in the induced estrus. Embryo flushing was performed 7-8 days postovulation. Following embryo flushing, donor mares were treated with prostaglandin F2alpha analog (cloprostenol 250 µg). The ERR increased along with the ITO (P = .01), with the lowest ERR (30.7%) for mares with an ITO of <4 days, and the highest (78.3%) in mares with an ITO of 10 days. The ITO from the donor mare in which the embryo was recovered did not have a significant effect on PR: ITO <6, 6 to 10, and >10 days were 74.6, 81.4, and 77.3%, respectively. The number of EPF and MO rate increased gradually along with the ITO (P < .05). In conclusion, the results of this study indicated that the ITO is positively correlated with the embryo recovery and the multiple ovulation rate.