As a taunt he would likely speak how humans are livestock who just exist to feed vampires anyway. Animals eat grass to be eaten by humans, humans eat vegetation to have their blood consumed by vampires, same thing to a vampire.

I get what he means but you don't see them breeding humans and roasting them, so they are just like milking cows only blood.

Crowley trying to rationalize it to Mika was interesting as well. Even if he's trying to justify it he still may regard humans as inferior.