[icegreentea]

I think every single one of those questions is missing yet another 'question' - that is, how much meat?

From a naive min-max approaching to building your diet, it generally pops up that -some- meat is super useful. Simply by doing that you ease all sorts of constraints on your diet, and allows you to optimize your veggies/grains for other stuff, instead of desperately trying to get all your iron and B12 in. Even from an overall energy budget point of view, -some- meat is super useful. There are large amounts of marginal land that is not really useful for large scale cultivation, but perfectly usable as feedland for free ranging animals.

[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.

[graeme]

A crucial question. I don't really know of any calculation that's looked at total food energy production based on sustainable production plants vs. animals.

I think we can safely assume the optimal balance is neither all plant nor all animal, but I am in no position to hazard a guess as to what the optimal balance is.

We're so far off from sustainable production of either plants or animals that the question isn't on most people's radar.