This retrospective study analyzed data from 505 inseminations with cooled transported
semen and 387 natural matings. The analysis shows that similar (P > .05) per cycle
pregnancy rates (PRs) can be achieved with cooled transported semen equal to that with
natural mating, provided that insemination is performed between 24 hours before and
12 hours after ovulation. Any earlier inseminations relative to ovulation yielded lower PRs
(P < .05) than in mares bred by natural mating.