You keep saying that many boundaries are arbitrary but it's gotten to the point that I genuinely don't believe you know what that word means. We all live in a society and culture that dictates things differently, due to our differing histories. The animals we choose to kill and eat, heavily fluxuate depending upon which culture you are apart of, and majority of the time it's quite a simple concept. Is the animal bred to be eaten? Then eat it. Is the animal not bred to be eaten? Then don't eat it, unless of course it's very sick. Your arguments seem odd and quite forced, so far I see 'Animals bred are good? Well slaves bred for slaves do slavery good!' to which is a very- Odd argument, because you are taking a perspective from foreign place and shoving it into our face as if to say that because another culture does it, that our culture too must agree with it but clearly we don't, because we don't have slaves. The other argument is 'If you would skin a cow, you would skin a dog' to which I say, yes and no. You don't eat anything that gives you benefits, you don't bite the hand which feeds you and for milenia animal companions (such as dogs, cats, etc) have been bred to be household pets and many studies show they actually benefit the person mentally. At the end of it, it's all about one's culture and where they see the line drawn, it's not arbitrarily drawn in the sand just '**** it', but done out of experiences and what the culture needs to do to survive.