Some horse breeders take a winter vacation usually to warm, sunny climates.
And, so will open and barren broodmares which did not become pregnant in the breeding season. Oh, they will not go to Florida, but they will take a reproductive vacation. Fall is an interesting reproductive time in broodmares. They go from their natural breeding season in spring and summer to a period of non-mating, or anestrus. Decreasing daylight in the fall causes a drop in the frequency of ovulation in the broodmare.