My first attempt at moving pigs onto a trailer in 2011 went poorly because I was unprepared and inexperienced. I showed up to the farm in Yelm to get the pigs with nothing but a horse trailer, and quickly learned that they would not simply walk onto it. Four hours later, covered in pig poop and exhausted, I managed to get both pigs into the trailer. It was not fun for pigs or farmer.
This time around, I heeded the advice of many and set the trailer up a day ahead of time in the pig paddock. They were initially scared of the trailer, but by putting all their daily feed inside it, they eventually warmed up to it. I figured that I would need to put the feed in the trailer the next day to get them to enter, but I was pleasantly surprised to find all five pigs sleeping soundly in the trailer. It was the driest spot in the paddock, and since I'd bedded it down with hay the previous day, they were happy to make it their new bed. I quickly closed the door, and was off to the Chuckanut Farmstead, pigs in tow.
I didn't have access to my landlord's horse trailer for the move, so I rented a 6 x 12 U-Haul trailer. It worked great--enough ventilation for a short trip, more than a ton of load capacity, and metal floors and walls for easy clean up. We kept it for a week and used it for our personal move as well.
Here's a link to more pictures from the move.