I'm always interested in adding new genetics to my herd, particulary berkshires. So when I ran across a litter of berkshire piglets, I bought them all. Some of them were a little small. So the problem is when you're introducing a new animal to your system, how do you teach it?
Here's my solution. Take a couple of medium sized pigs and put them into the pen with the small ones. Yes, the bigger pigs do get to eat first, and drink first, but they also show the little guys how to eat and drink.
There's a pretty dramatic size difference between pigs, and they grow fast. In a month or so the little guy in the center will be the size of the pig on the left, and in another month the size of the pink pig. The little guys spend a lot of time trying unsucessfully to push the bigger pigs around. Mostly the bigger pigs ignore them. Within this little herd the pigs will form friendships and hang around with each other. When I move them out to the pasture they'll continue to socialize mostly with their friends that they met when they were little.