[aaronblohowiak]

How much, how is it produced and what kind?

farm raised alantic salmon have a feed to gain ratio of about 1.2, which is amazing (cattle are about 5x worse)

Also, there are some serious doubts about whether veganic farming could support current global population levels (manure is a great fertilizer!)

Of course things get more complicated in terms of efficiency when you start thinking about dairy and fertilizer and hide production.. the thinking around permaculture ( http://en.wikipedia.org/wiki/Permaculture ) takes this "whole system" approach to agriculture and would be necessary if you wanted to e.g. create a self-sustaining colony on mars.