The Bible says in Genesis 9:3
Every moving thing that lives shall be food for you. And as I gave you the green plants, I give you everything.
Nowadays it is consider politically incorrect to defend the killing of animals even when its purpose is to feed us. Some people even think it is "bad" from us to kill an animal to eat it.
Many people complain about the way animals are treated before they are killed, like if they were "things" or some kind of "industrial" machinery. They compare them with human beings sometimes and try to show how bad it is kill another animal, as if we were just animals as well, at the same level as them.
According to Catholicism, what should be our attitude be towards animals? Should we consider them only as "things god put on earth for us to use"? Or should we show some kind of respect to them in the way they are treated / killed ?