It's mostly about how cruely we treat food animals normally that I have an issue with. Hunting, for example, I view as a morally acceptable method to get meat. It's natural and the animal is living a life as a natural animal should. If the pig isn't raised cruely, I think raising them to help a person live a life is a moral good. That person took a lot of resources to get where they are, and they have the potential to do a lot of good. The pig did not take nearly as many resources to raise and does not have much, if any, capacity to do good besides by dying. Whether they should exist at all is the real question, and I'd say probably yes, again if it isn't cruel.