I use mine to feed the wolf farm. Make yourself a butcher knife or turn friendly fire off and you can kill them just fine.

normal pigs not a whole lot.. the effort required to keep them breeding is a headache. But if you can get some 2 or 3 star pigs breeding meh... its a meat and leather farm galore.

Originally posted by tomelectric:

So we've tamed pigs, now they are over running the place we let go 20 and now have 15 again. Why can't we kill them? What are tamed pigs good for?

You need to make a butchers knife to kill them.

They are there to remind you that you could of made a Boar farm in the very beginning, but oopsie you don't have time for that. 100 game days later, you don't need Boars at all, but you have a Boar farm.