This is simply a matter of practicality. It has nothing to do with idealogy, it's simply a fact that anyone going to live on Mars (a least in the beginning) wil

This is simply a matter of practicality. It has nothing to do with idealogy, it's simply a fact that anyone going to live on Mars (a least in the beginning) will need to become a vegetarian if they aren't one already. Eating vegetarian is dramatically more efficient, energy wise (I'm not trying to be a vegetarian apologist here, I am quite omnivorous myself, it's just a statement of fact), and any martian colony simply won't have the resources to waste on meat. Meat is a luxury.