I would be inclined to have a word with your market auctioneers, explain the situation and consider their advice on how to sell them - if you're looking to recoup the cost of their feed you may not succeed but pig prices have picked up in recent months. I've never taken in a pig that old for pork but I think it likely the meet would be rather tough and 3 well grown pigs would produce a mountain of sausages. The quicker they're gone the sooner the feed bill ends.