The animals don't know any better than how they were raised. They aren't born with standards. Sure, they are born with basic instincts, like pain = bad. But they don't huddle in groups to exclude those who have a different face. Don't associate them like that with humans.
And chickens is even worse. Haven't you ever seen factory farmed chickens? Literally tens of thousands of chickens stuffed into a barn smaller than my house (and I have a pretty small house). Left with food for 6 months. Then killed for meat. Do they complain? Nope. It's humans "complaining for them" that's the problem.
Yes, the fact that pigs are bred to be killed is founded by humans. I've never heard of a cow raising a pig to eat it
Pigs are different to humans. Humans, from millions of years ago (or whatever, I don't do History...) raised animals to eat them. It's the same as growing vegetables to eat them. Why aren't you all complaining on that? Biology shows us that vegetables are living creatures too, should we stop eating them?
On Jakg's last post, I don't think anybody was saying mis-treating animals is right. What I meant was that I'm not going to fondle every animal (200+ cattle), but should they need veterinary attention or whatever, they will of course have it. They're kept in 30 acre rotating fields for the summer, and fed of haylage in the cattle sheds in winter. They have a good life. Maybe not by human standards, I've yet to see a bullock enjoy LFS as much as me, but by animal standards, they're happy. To use the relevant phrase, happy as a pig in shite...