Thinking about eating meat

A long time ago, I meditated on the idea of whether humans eating meat was morally acceptable and I concluded that it was, so long as the animal was still respected as a living being. I hate hearing how animals are so badly mistreated on "factory farms". I mean, it's true that they're going to die, but is that any reason to treat them as if they have no intrinsic value other than for food, completely oblivious to any pain they might feel during their lifetime?

I think that animals should be treated with respect, even from a legal perspective. Maybe not given rights as a full human being, but something. For example, I think it should be illegal to shoot your dog one day, just because you feel like it. Severe mistreatment or neglect of pets should also be illegal.

Yesterday I was talking to someone about this subject, and he (a vegetarian) was asking "what moral authority do we have to kill animals?" I'm still pondering this, actually. My first thought is that it's not a matter of moral authority as much as an issue of moral boundaries. Saying an animal is of "less value" than a human being is not necessarily saying this fact comes from any source of authority as much as saying this being is "not human". If you went really far with it, you could ask what gives the moral authority to kill plants? I would say that plants are nothing like a human being, so there's no dilemma whatsoever. On the other hand, it is dangerous to our moral sensiblities to allow the wanton killing &/or mistreatment of creatures we see as near human. In U.S. culture, there's a tendency to humanize animals in literature and media while simultaneously depriving the real beings of even the slightest respect for their intrinsic life. That seems really messed up.

What's my point here? I don't have one really, because I'm still trying to think this through.