Meat and resources

I’m reading pieces of the book “Feeding the World” by Vaclav Smil. Among other things, he compares the energy efficiencies of diary, eggs, and various meats and discusses potential improvements in production.

One of the most powerful points he makes is that, from the perspective of energy-efficiency, or land-efficiency, or maximizing the earth’s carrying capacity, there’s an optimal level of meat consumption that is probably less than the American per-capita average, but definitely nonzero.

The usual argument is that it takes 10 pounds of grain to produce a pound of beef, so we can feed more people by not raising beef. But not all livestock is grain fed. In particular, a lot of livestock grazes on pasture land, agricultural residues, and legumes planted in rotation with food species; these are not in competition with human food crops. Sea animals generally do not compete with human food crops either. The implication is that the best-managed food supply would involve some meat production, even if you use all the land possible for human crops.

One might extend this to decide that it’s (environmentally) ethical to have a diet that includes a small amount of meat. Smil also gives some evolutionary arguments for why eating some meat (say, a tenth of that in the American diet) is biologically adaptive for humans.

If one decides that some meat should be consumed, then there are more and less efficient animals to eat, and Smil presents a lot of quantitative data on this. On every measure, beef comes out the worst (e.g. 5-8% protein conversion efficiency). Eggs (30-40%), and particularly milk (30-40%), and salmon (40-45%) come out pretty good on conversion efficiency. Eggs and milk also do well on land use, chickens and eggs on water use. Pigs look good a number of measures, partly because they eat a lot of agricultural waste and they digest it efficiently, but I actually think Smil gets it wrong on the benefits of pigs because he’s ignoring the life cycle issues with hog waste (nasty water pollution).

Overall, I’d say there’s strong support for lactoovo vegetarianism. There’s also good support for eating, say, fish but not other meat, or poultry but not beef, from an energy-balance perspective. This is also a conclusion I drew from the life-cycle analyses of meats in The Consumer’s Guide to Effective Environmental Choices..

  1. #1 written by allison June 24th, 2005 at 16:50

    If you come to the vegetarian side, I’ll support your decision! I’m excited to check out Smil’s work too though.

    Here’s a link to an article that really resonated with me. It raises a lot of good issues including the grain:meat ratio that you already mentioned. I agree with you that grazing is better than grain-fed, but I’d rather see land in its natural form than used as grazing fields for livestock.

    Happy eating!

    RE Q
  2. #2 written by Christopher Weber June 30th, 2005 at 16:55

    I’d also like to point out that it’s not only pigs that have lasting life cycle impacts, but poultry and cows as well. All of these factory farms contribute to horrible air quality issues (believe me, I’m from Iowa and have driven past each of these different kinds of prisons, and they all smell slightly different but horrible) as well as water quality issues from manure runoff, etc.

    And let’s not even get into the LC input factors that are NOT just food of course, but land that could be used for other production (or as Allison points out, the simple utility of natural beauty) as well as several kinds of drugs and antibiotics if we’re not talking strictly organic meat/dairy/eggs.

    Similarly, even the ‘other kinds’ of food that are not in competition with human food above (especially legumes used in rotation with corn for human consumption) have their own associated LC impacts that would be avoided if the plants were not needed for animals.

    I do buy the fish argument, if you ignore all the harmful interplay the fishing industry has on coral reefs and other water-based life.

    Still, no matter what way you cut it, we’re still only talking environmental ethics–admittedly the veggie argument that rings home truest to me–and not several other kinds.

    Interesting stuff, though . . . I’d love to read more on it!

    RE Q

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