Heat detection Timing of the insemination of sows is critical to success. Sows are inseminated twice during standing heat. The first insemination should be done 12 hours after the sow will stand for the producer. The second insemination should be done 12 hours after the first. One of the most common reasons for poor litter size is inseminating the sow too early in the heat period.
Proper timing requires twice daily checking for heat.
Heat checks should be done in the presence of a boar, who will make the sow show stronger signs of heat. Can sit on sow's back without her objecting Redness inside vulva is waning Mucus inside vulva is changing from clear and watery to opaque and sticky. Check for heat 24 hours after the second insemination, if the sow is still in heat then she was inseminated too early. Most catheters have tips shaped more or less like the tip of a boar's penis. Disposable plastic or reusable rubber catheters are available from commercial AI stations.