Logic fail.
Nutrients are CONCENTRATED in animal foods...not 'lessened'. This is why carnivores have such short intestinal tracts. Meat is easy to break down and very high in nutrients. Entire cultures have thrived on diets consisting almost exclusively of animal matter.
Cow eats acres upon acres of grass. Nutrients in grass are used by and concentrated in the cow. We eat the cow, we get the nutrients from acres of grass. (Sort of--that's pretty simplified).
This works out particularly well for us, since we can't digest grass.
I also have no problem with slaughtering and processing an animal for meat. Doesn't bother me. In fact, I cannot look at a cow without thinking of a ribeye, lol. I love animals--all of them. I think they're beautiful, amazing, and endlessly fascinating. I also think that we're part of the food chain, and many arguments for vegetarianism are deeply flawed.