Optimizing the use of frozen–thawed equine semen

This manuscript is a review of current protocols, advantages, and disadvantages of breeding mares with frozen–thawed equine semen. Issues affecting pregnancy rates are discussed, including proper mare selection, induction of ovulation, insemination dose, timing of insemination (single-dose versus multiple-dose insemination), methods of insemination (transrectal-guided deep-horn versus hysteroscopic insemination), and post-insemination mare management procedures. In a retrospective analysis of breeding records, a single-dose of frozen–thawed semen was inseminated within 6 h post-ovulation; the pregnancy rate (14–16 days after AI) was 67 of 149 (45%). These results were comparable to those previously achieved under commercial conditions, as well as previous studies using multiple doses of frozen–thawed semen per estrous cycle. In conclusion, these data provided evidence that, with appropriate breeding management, an acceptable pregnancy rate can be achieved in mares with a single-dose of frozen–thawed semen (per-cycle) inseminated within 6 h after ovulation.