Sows will come into heat 3 days after their piglets are weaned and then have a heat cycle every 21 days. Most pigs have very regular cycles, we can usually predict within a 24 hour period when our sows should be in heat.There are a few things to look for to know when your sow is in heat. The first thing you will see is that her vulva starts to get bigger a few days before she is ready. When you see this start testing if she is in "standing heat". You do this by pressing down on her rump (it helps to talk to her and rub her sides before you do this) and see if she moves her back end away from you or if she stands still. If she stands, watch her ears, when she is ready she will pull her ears together like you can see in the picture. Even if she is standing, I will usually not try insemination unless she is doing the ear thing too. Unfortunately, the girls picked a really miserable rainy day with warmer temperatures to be ready, so things were a muddy mess. Both girls were ready on the same day. We do not have to put them in stocks or restrain them in any way, they are happy to stand for the insemination. The hardest part was keeping the one sow entertained while I inseminated the other.
Our sows are registered Berkshires. We use artificial insemination to breed them and order semen from North Iowa Boar Stud. Bill has excellent customer service. Artificial Insemination in pigs is not hard to do. You do not need special equipment to store semen. It comes fresh and just needs to be kept at 60'F (we use a seedling growth mat with thermometer inside a cooler to keep it at temperature) and stays good for up to a week. The fresher you can use it the better but make sure you have it when the girls are ready. We keep track of heat cycles even when we are not breeding them so we can predict when they will be ready and make sure to have semen on hand. Keep the container with semen warm in an inside pocket when you go out to do insemination in the winter. Inseminate with one dose of semen every 12 hours until they are not in standing heat anymore.
They should have come into heat last week if they were not bred but neither of them showed signs of being in heat so they should be pregnant. Pigs are pregnant for 114 days (three months,three weeks and three days). They were inseminated on January 12th and 13th so we are looking forward to piglets at the end of the first week of May.