Contact your local county extension office. They may know some people. Also the leader of the 4-H groups can point you to reputable people. Maybe your local feed store would have a posting. The last place I know of is Craigs list.
I'm getting 2 or 3 pigs in the fall (October/November), and am trying to think of a few vegetables I can plant this summer that will supplement their feed. I'm planting right where the hogs were raised 2 years ago, so most everything will be harvested before the pigs arrive. I could throw down...