What if, in a galaxy far, far away, a technologically advanced race of beings reared, farmed and slaughtered human beings for food -- and their justification was that human meat tasted delicious and was good for the economy.
Would this advanced race of beings have the right to farm humans for food, given their technological and intellectual prowess?
If not, then ask yourself the following:
What gives us the right to rear and slaughter animals for food, and why is it morally just to treat animals in a way which we wouldn't wish to be treated by our superiors?
Have we forgotten the ancient wisdom of The Golden Rule?