Morality doesn't exist outside of "socially prescribed conclusions", it's actually a pure social thing, it has no other function, but to help individuals make socially acceptable choices.
That is a pretty bold proclamation. Still, the thought of killing and torturing an animal for your pleasure seems to violate ethics centered around reciprocity. You know, the old "do unto others...". Even if that rule is not based on something objective it still seems more axiomatic than, "Mmmm, they taste good therefore I have dominion."