A feedlot feeds corn or wheat to animals who are then consumed by humans. There are therefore two levels of cost: first the production of the grain feed and second the raising of the animal.
I am a vegan for health reasons, so I look at this two level procedure in meat production from an economic standpoint. Meat production is a huge waste of economic resources, more than doubling the cost of producing the same nutrients in vegetable form.
Here is a simple complete human diet: pasta and lentils, plus four pills per day (multivitamin, B12, calcium carbonate and Omega 3/6/9).
Do you eat grass? Didn't think so.
As for efficiency eating, I simply and matter of factly don't care. I don't eat in order to economize production, because there is absolutely no shortage of production.
People do not go hungry because I had bacon instead of oatmeal. They go hungry because of despotic political systems that control the food supply.
Complete human diets don't require supplemental vitamin pills. A truly simple human diet is a loaded baked potato (butter, sour cream, salt, maybe cheese) a well marbled steak, and a side of brocolli...Yum! Omnivores have nothing to worry about, its all good and natural.
Livestock agriculture is THE MOST EFFICIENT use of natural resources and produces FAR AND AWAY more useful products. I love farming and come from a long, long line of farmers, but also come from a long line of cattle ranchers.
You want to be vegan, fine. You want to subject children to it, that's child abuse. You want to rationalize it as "better for the environment," go ahead and kid yourself, but when you emotionalize it with such false claptrap and cause young girls to adopt a vegan diet because they think its "being nice to animals," YOU bear the responsiblity for all the health problems, including osteoporosis, that those girls will get later. Listen, I've been around vegans and their kids. I'VE SEEN ALL THIS and all the allergy problems and emotional problems those kids have -- taking pills is THE WRONG WAY and THE DUMB WAY to live healthily. And I've seen their parents, adults, continue to insist that two plus two equals five because it should!
I can respect vegetarianism. Veganism is foolish dangerous vanity to the utmost.