All the breeds mentioned in Mark's article today are breeds raised by U.S. CAFO farms. It was said they naturally gained weight (and fat) quickly.
But think of pictures of wild boars you've seen. They're not particularly fat. Our pigs sure are. Most pigs are slaughtered at 3 months and 100 - 130 lbs. A sow, 6-9 months old, will weight over 600 lbs, and she's so heavy she can hardly walk. So, you wouldn't want a U.S. breed.
There are 1 or 2 breeds in Eng. and/or EURO that are less 'adapted' to CAFO. I've seen pictures but don't remember their names. So - if you had some of these omnivors, what would they eat. Meat, fish, leaves, roots and fruit, just like us. Maybe you'd have to also raise rats and let them loose in the pig pastures. (They could spend a day in my back yard to eat gophers.) Fish meal could be supplemented, and lots of the kitchen's leftovers. Do pigs eat snakes? We have lots of those also.
"When the search for truth is confused with political advocacy, the pursuit of knowledge is reduced to the quest for power." - Alston Chase