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.