As I mentioned before, there are different realms of existence - humans are a realm of existence and the animal realm is a realm that is below the human realm. That is a starting point. But as to raising animals intentionally just for food, think about this from a different point of view. Almost all pigs would never have been born unless people ate pork, pig meat. They wouldn't actually be born. It is an interesting way of looking at things because, on another level there is the concept that if a being is born in order to feed humans, the being actually makes good Kamma. So the pig that is born specifically to feed humans, actually makes good Kamma by being killed in order to feed humans. That is an odd way to look at things.
But what is happening to the little fetuses, human little babies, pre-babies, they are simply being murdered, slaughtered. This is very different to the animals that are feeding us.