ASC-152: Manipulation of the Estrous Cycle in Swine

As production schedules become more intense, greater demands are placed on the reproductive system of the gilt and sow. Compared with their predecessors, today’s female swine are expected to attain puberty at an earlier age, breed and become pregnant the first time they are mated by the boar, farrow larger litters, wean a larger number of heavier pigs, return to estrus in a shorter time period after weaning, breed and settle on the first service after weaning, and remain a productive part of the sow herd for a longer period of time. Unfortunately, it is quite difficult for the gilt and sow to live up to these lofty goals. While there are no magic elixirs that can replace the need for sound management and husbandry, producers can use various hormonal treatments to help maintain reproductive efficiency. These hormonal treatments can be used to induce puberty and synchronize estrus in gilts, minimize the wean-to-estrus interval in sows, and treat the anestrous condition in gilts and sows. To effectively use these hormonal treatment strategies, a clear understanding of the interrelationships among reproductive hormones is necessary. This publication gives a brief overview of the reproductive anatomy of the female and addresses how the hormones involved in female reproduction change and influence one another during an estrous cycle. Also, several hormonal treatments that can be used to manipulate the estrous cycle of swine are discussed.