Nose rings and other such devices for control of the animal are generally forbidden by FFA organizations. Up to 200 pounds, they're strong, but I can't recall ours at that age ever really challenging fences. Over 200 pounds & up, a single strand of electric fencing, a few inches above the ground will stop a pig in its tracks (usually.) Something like this:
http://www.premier1supplies.com/fencing.php?mode=detail&fence_id=133 works to stop pigs. The energizer can get a little pricey though, but pigs don't need nearly as much voltage to be effective as a lot of other animals; they're actually at the lower end. The lack of a thick coat of fur is one reason; but even so, it still takes quite a pop on the nose before other animals will stop challenging the fence. But, pigs are smart - OP could probably borrow a charger for a week; and after a week, the pig will know, "stay away from the fence." E.g., I had a horny goat climbing over a 3 foot fence to get to female goats. I ran a strand of electric just above the top of the fence. 3 zaps in 5 minutes & I've never seen that goat try to climb over the fence again, even with does in heat 10 inches in front of him on the other side of the fence.