there's a small boar at the lower right of this photo that gets sold on the 10th, and the rest of these are gilts and sows. All of these animals were born this year, and they've all made it past the first culling. I think I'll over-winter 24 females and 3 males.
What I'm looking for in a good female pig is stance -- wide stance for the legs, good lion definition when they're thin, a little bit of an arch to the back (when they're carrying 100lbs of piglets and afterbirth, the back straightens out, so it's good to have a little upcurve. I'm less picky on coloration, although some customers seem prefer one color or the other. I've had two korean customers who wanted all-black pigs and would take no other, for instance.
I'm also looking carefully at the "lowline" of the pig. How many nipples does she have -- I'm looking for 14 or 16, and they've all got to be in good shape.
If they're physically perfect then you move onto the handling characteristics. Is she friendly and does she seem to be thriving in the current system? Putting on weight as she should and getting along with the rest of the herd and herdsman? Is she calm enough to be handled easily and safely, or excitable and flighty? Does she respect the electric fence?
If a pig passes all of those tests then she becomes next years gilt or sow.
For boars I'm looking at the same stance and general characteristics, but culling heavily on behavior. If they're not absolutely sweet and easy to handle at any age they go. It's just too big an animal to have a bad attitude, so throughout their lives I watch them to make sure that they're acting appropriately to me and in the herd.
Squabbles between pigs happen all the time; they maintain a status system that determines who gets to eat first, drink first and where they get to sleep. Some sleeping spots are considered more desirable, and the higher status (usually bigger, older) pigs get those. So I don't consider a little bit of squealing or roughhousing to be anything unusual - in fact, I'd think it was unusual to not have any - but now and then you run across a pig that enjoys it, and that's the pig that's watched for a temperament cull.