Just keep them like lifestock (e.g. on a cotton field or labour camp as we have done in the past), and killing them should be completely fine according to your logic.

Following the reasoning that I've posted in another comment, another species keeping us as livestock wouldn't be doing something immoral in my book; they're defending their own interests, in detriment to ours. I don't expect for example a jaguar to put my self-preservation above its cub's desire for food.

And similarly it wouldn't be immoral if we fought against it.

Contrariwise to vegans I'm not putting humans on some holier-than-thou ground with intrinsically better moral grounds than the other species; it boils down to defence of one's own interests. Take a clue from the fact that my avatar is a smoking chimp dammit.

Who cares about the victims if we just declare them lifestock. Great ethics!

Appeal to emotion and other forms of stupidity/fallacy/irrationality don't work well against me. Try something else.

Although I'm suspecting that you guys' approach is something else: ad nauseam / sealeoning, is it?