Pigs, like all of our livestock species are herd animals. They are very social. They also have a very strong sense of hierarchy. Each pig knows, claims, or is put in its place. The claiming and putting is often extremely violent, but, in my limited experience, only occasionally dangerous. I have seen little more than a scratch here or there after a battle for position in the hierarchy. However, in spite of the fact that little harm generally results, for someone who doesn’t like to see animals suffer or experience stress, watching these herd hierarchy conflicts can be quite difficult, especially when a dominant animal goes after a submissive one and won’t let up. It doesn’t happen all that often, but when it does it is ugly. I have felt compelled to intervene once or twice. Usually, hierarchy conflict is explosively violent, but over quickly.
(A note on intervening: Even small animals are substantially stronger, relatively speaking, than we are, and when they are in a fight, no matter how tame and sweet the animals are under ordinary circumstances, they might turn on you. Never, ever, try to get between two large animals in a real battle, especially if one or both of those animals is a male and reproduction has anything to do with it. The previous owner of my farm, who knew absolutely nothing about horses, but started a horse farm anyway, was nearly killed by a stallion about two months before the closing on the property when he tried to get between that stallion and a mare who had gotten out of her paddock. The stallion broke the guy’s shoulder, broke a bunch of his ribs, smashed his head, and nearly broke his back, all in about five seconds.)
Because of this strong and violently established sense of hierarchy, mixing groups of pigs is a challenge, and should really be avoided if possible. It is not always possible, however. When it is necessary, the animals should ideally be able to meet and get to know each other through a fence line for a few days. This introduction mitigates, but doesn’t prevent entirely, the conflict when they are put together.
The first time I had to mix two groups of pigs was last year. I had a group of three pigs that I needed to put in with a group of ten. The ten pigs were Berkshires, which are black, and the three were commercial crosses, of which two were black and one was white. When my mother was a freshman in highschool (about 1962?) her biology teacher tried to use the example of the seemingly color-based conflict between gray and black squirrels as justification for racism (this was in a school in a suburb of Syracuse, NY, not somewhere in the south, by the way). In spite of the fact that such a justification for racism is absurd, there does seem to be some sense on the part of pigs that pigs that are substantially different colors are less welcome than those that are the same color. That poor white pig suffered at least twice as much abuse as those two black crossbreds. It was a week before those crossbreds, especially the white one, could sleep with both eyes closed.
This year so far I have had to mix pigs four times, and each time has gone pretty smoothly, even though I have not had the opportunity to introduce them between a fence line. They fought and chased each other around for a while, but after a few hours, they had settled down. The boss in one group wore herself out trying to put down all five new pigs. She put three down pretty easily, but the other two felt they deserved a higher position in the group. It seems that she kept her position, but by the time she was finished she was exhausted. She walked off and collapsed in a heap and then rolled onto her side, her chest heaving. I went over to make sure she wasn’t cut or hurt. When I started rubbing her shoulder she sat up on her butt like a dog and leaned into my fingers. When I stopped she lay back down and took a great big breath. I checked back in on her about an hour later and she was up rooting around in the barnyard. The new pigs were at a respectable distance from her. I could see them watching her out of the corner of their eyes.
Yesterday evening, just about an hour before dark, I put four new pigs in a group of ten, and that went very smoothly in spite of the fact that three of the four pigs were a different color (so much for the color theory?). They hardly fought at all.
What I have learned by reading and through my very limited experience:
- When possible, let the groups get to know each other through a fenceline for a couple of days before putting them together
- Try to introduce groups in as similar numbers as possible. A single pig introduced into a group will likely have a lot of trouble
- Try to match groups by size, or introduce groups that are opposite sizes. I introduced eight thirty pound pigs into a group of four 100 pound pigs and the bigger pigs hardly did anything more than sniff the little pigs and occasionally toss them with their snouts
- Pigs seem to have a sense that differently colored pigs are less welcome than similarly colored ones, so don’t be surprised if differently colored pigs suffer more abuse
- Even when the introduction goes badly, the violence is generally not dangerous, and eventually the pigs will work it out. Be prepared, however, to deal with a week to ten days of feeding, watering, and sheltering, the abused pigs separately until things settle down. I had to feed and shelter those three crossbred pigs separately for about four days. The other pigs weren’t letting them eat or near the shelter at all
- The damage done by big pigs to other big pigs is more likely to be substantial than that done by little pigs to other little pigs. A guy I met recently nearly lost a sow after backing her out of her farrowing crate after five weeks and putting her directly into a pen with two other sows and a boar (all of which she had been with before). He has had pigs all his life, but he only recently started using farrowing crates. He hadn’t realized just how much muscle and body condition a sow would lose after doing nothing but laying down and standing up for five weeks, all the while producing gallons and gallons of milk. In less than an hour, one of the other sows nearly killed her. It took three hours for her to muster the energy to walk fifteen feet from the breeding pen to another pen. She would take a few steps and collapse and just lay on the ground for an hour. It was two days before she could stand for more than five minutes at a time. She was pretty much recovered after about a week
- Never, ever get between two animals in a conflict over reproduction
