I don't necessarily agree with the earlier poster but how we slaughter the animals isn't really the issue they have. If aliens came and promised to provide for

I don't necessarily agree with the earlier poster but how we slaughter the animals isn't really the issue they have. If aliens came and promised to provide for you for your whole life but on your 30th birthday they would kill you painlessly would you take that deal? What gives us the right to impose that kind of deal on other living beings?