Please buy a book on keeping Rare Breed Pigs before you go any further with your
project.
Pigs are not ruminant animals, and have to be fed every day, they can not live on grass.
Pigs dig and eat worms, mushrooms, roots etc, but need to have proper nutrition.
I would advise you to talk to someone face to face that keeps pigs, or get a good book
for your sake and the pigs
Happy Pig Keeping