Today we received semen from our chosen boars (breeding males) in the Midwest. We are planning to breed 7 sows and 3 gilts this weekend. Let’s talk swine reproduction.
Female pigs go by two different names. Sows are older females that have given birth to at least one litter. Gilts are young females that haven’t given birth yet. When piglets are born, they weigh around 2-3 pounds each. Within 6 months, they are sexually mature and weigh about 300 pounds.
Sows cycle every 21 days, much like humans. When they are ovulating, they will “stand” for the boar. They do not move. If you sit on them, they will just stand there. There is also “ear popping” where the gilt or sow will pin her ears back against her head and flick them forward occasionally while there is pressure on her back. Normally if you put pressure on a pig’s back, they will squeal and run away quite aggressively.
This is one of my all-time favorite pictures of a gilt standing. This was 4 years ago and all of my kiddos were so young!
We do not “live cover” any of our females. We order semen from genetically superior boars that will cross well and strengthen any deficits we see in our sows and gilts. This year we have chosen several different boars.
All of the sows and gilts have been synchronized to come into heat at the same time to minimize the farrowing window. Farrowing is the term we use for pigs giving birth. We like them all to farrow within a week of one another so that if there are any issues, we can cross-foster piglets to other sows.
The sows are synchronized by giving a pregnancy hormone known as “Matrix” which is altrenogest (a man-made progesterone). The sow thinks she is pregnant, but when the Matrix is stopped, her body realizes she is not pregnant and begins to cycle so she can be bred. This usually happens within 3-5 days of stopping the Matrix. We stopped Matrix on Tuesday (last day was Monday) so they are all beginning to show signs of heat.
The semen comes “cooled” which means it is live, not frozen. We keep it in a wine cooler (our “swine cooler”) at 65* F. It must be rotated twice a day to keep the sperm cells mixed with the extender, which is food for the sperm cells to keep it alive until it can be put into the sow.
Each boar comes labeled and color coded so that we don’t get mixed up when we breed them. Even crossbred show boars have genetic lines that we follow.
Swine gestation (pregnancy length) is 114 days – or the easy to remember “3 months, 3 weeks, 3 days”. Once the sow weans her litter, usually in 3-4 weeks, then she can be bred back immediately, allowing her to produce 3 litters each year.
We will begin breeding when they are truly standing. I will update you as we begin the process, showing you the methods we use.
Dr Vet Sonya 