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-hom 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 Al) 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. (c) 2008 Elsevier Inc. All rights reserve