This article isn't something I plan on putting a lot of energy into defending, I simply see it as interesting food for thought:
http://www.mercola.com/2000/apr/2/vegetarian_myths.htm
"MYTH #1: Meat consumption contributes to famine and depletes the Earth's natural resources.
Some have argued that cows and sheep require pasturage that could be better used to raise grains to feed starving millions in Third World countries. Additionally, claims are made that raising livestock requires more water than raising plant foods. Both arguments are illogical and simplistic.
The pasturage argument ignores the fact that a large portion of our Earth's dry land is unsuited to cultivation. The open range and desert and mountainous areas yield their fruits to grazing animals (1).
Unfortunately, the bulk of commercial livestock are not range fed, but stall fed. They do not ingest grasses and shrubs (like they should), but are fed an unnatural array of grains and soybeans. It is true that these foods could be fed to humans.
The argument here, then, is not that eating meat depletes the Earth's resources, but that commercial farming methods do. Such methods also subject livestock to deplorable living conditions where infections, antibiotics, steroids and synthetic hormones are common. These all lead to an unhealthy animal and, by extension, an unhealthy food product. Organically raised livestock, then, is a healthier and more humane choice (see myth #15 for more on this topic)."