I always, from the 5th grade when we read Charlotte's Web, wanted a pig for a pet, UNTIL I saw what they can do to the yard with the incessant rooting up the lawn. That pretty much cured me of that little dream.
As for the pigs, they view everything as food. If they can get you down to the level of their snout and keep you there, they WILL eat you.
The chickens are just scavengers and cannibals. You should see what happens when you toss a chicken egg into the air in a chicken pen. They try to kill each other to get to that broken egg.
They all need to be eaten if for no other reason than to keep them from evolving into something we cannot defend against.