I was thinking much the same as I wrote it, but didn't want to overburden an already long comment. Here though, I'll say that large cattle consume about 30 calories for each single calorie their meat will provide. Poultry seem more like 10 to 1.

I'll own up to some level of hypocrisy on this as I am not a vegetarian, but I also won't complain much if further population growth makes meat consumption unsustainable when it means people starve. (I don't think we're there yet: world hunger right now seems to be more about other factors, economical and otherwise. I'm open to opposing viewpoints on it though)