About a month ago, The Council for Agricultural Science and Technology (CAST) put out a report on Animal Feed vs. Human Food. I just got around to reading it and it has some interesting calculations and statistics.
The report addresses the common claim that livestock production is wasteful because crops that could be fed to humans (e.g., corn, soy) instead go to animals. For example, here is an old quote from David Pimentel, a former Cornell Professor:
If all the grain currently fed to livestock in the United States were consumed directly by people, the number of people who could be fed would be nearly 800 million
For another example, here is PETA:
It takes up to 13 pounds of grain to produce just 1 pound of meat
I think one of the most colorful ways I've heard this criticism expressed is that eating meat is like going to the grocery store and buying 13 (or 6 or 3 depending on which source you read) boxes of corn flakes and throwing 12 down the garbage.
This discussion misses at least three important issues. First, many animals (particularly cattle) eat things we humans can't - mainly grass and hay. Second, one needs to look at more than just calories in and calories out because there are other nutrients - particularly protein - that our body needs. I'll get to the third issue in moment.
Jude Capper had some interesting graphs in her presentation of the CAST report that directly address the first two issues. The graphs focus on the input-output relationship between human-edible protein and calories.
The above graph shows that dairy and suckler beef (that's their name for grass fed beef I believe) generate more protein than they consume from human-edible sources.
The next graph shows the results for calories (or energy as it is titled). They report that dairy produces about twice as many calories as it takes in from human-edible sources
Still, even these statistics suggest that it is "wasteful" to consume certain types of meat and animal products because they yield less energy or protein than they consume.
That brings me around to the third reasons why some these comparisons are a bit misleading: they focus only on costs and ignore benefits. Here is what I had to say about that a few months ago:
One fact that is often forgotten in meat debates is that it isn't sufficient to look at the amount of energy (or crops) expended to get beef. We also have to look at what we get. Most people really like the taste of meat.
Almost no one looks at their iPad and asks, "how much more energy went into producing this than my old Apple II." The iPad is so much better than the Apple II. We'd be willing to accept more energy use to have a better computer. Likewise a nice T-bone is so much better than a head of broccoli. I'm willing to accept more energy use to have a T-bone than a head of broccoli.
Now, if my T-bone consumption is imposing costs on others, let's talk about that. But, here the focus would be on the issues causing the externality (e.g., CO2) not on meat per se.