Thursday, May 13, 2010

Converting Grass into Meat

I frequently hear the "fact" that livestock production is an inefficient use of land, so I thought I’d have a little fun and dust off some of my old pasture management information. We can debate the numbers, but I don’t think I’m too far off ...

Let's assume the following:

- Dry matter yield from perennial ryegrass & white clover pasture of 10,000 lb per acre
- 75% of the pasture dry matter produced is consumed by the grazing animal
- A conversion rate of 14 lb of pasture dry matter per lb of hanging weight
- An edible yield of 65% of the hanging weight
- A cooked yield of 56% of the raw weight
- A per meal protein requirement of 4 ounces of cooked meat
- 3 meals per day

Under these conditions, a piece of pasture less than 209 x 209 feet could produce enough meat to supply a person's daily protein needs for 260 days (not to mention the lovely fat!). Remember that this land can be completely unsuited to the production of grains, fruits, or vegetables.

If we could bump the pasture yield to 15,000 lbs of DM per acre, we could produce sufficient meat to supply a person's daily protein needs for 390 days!!

Oh, and by the way, perennial pasture produces about as much root dry matter as it does above-ground dry matter, thus fixing more carbon. Even poorly-managed pasture is equal to woodland in terms of "fixing" carbon, while well-managed pasture is many times better.

This from a perennial "crop" that requires minimal fertilizer, pesticides, equipment, or petroleum to produce. But it isn’t “green” ‘cause it’s not vegetarian!



  1. Great post, this topic needs more development because it isn't simple. Pretend for a moment that soybeans were safe to eat (which they might be if you ferment them) and that you grew soybeans on that acre. A few short and probably questionable google's gives me 50 bushels/ per acre, 50lbs/bushel and 60 gms protein per pound. That comes out to 430 grams of soy protein per day- enough to feed six people. Even if I tightened up the conversion factors there is plenty wrong with leaving it at that. We need to consider soil erosion, availability of arable acreage, other nutrients, and probably more.
    Are you up for doing a legit comparison on this? The world needs it, and there aren't that many people with your educational background, knowledge and perspective. If I can help in any way let me know. I have no educational background on this topic, but when I was five they taught me to read...

  2. Thanks! Developing this further is something that I want to do. I agree it isn't simple, although it's frequently stated as if it is. For example: Animal protein and soy protein are not equal. Animal protein is complete protein. Soy protein isn't. Some other source of protein will be needed for human health. And that's ignoring the substantial anti-nutrients that soy contains, many of which are NOT “inactivated” by natural fermentation (and VERY little soy products in this country are produced by naturally fermentation). I agree with your points about soil erosion (greater with soy production than with pasture), greater acreage available for grass production than for field crops, lower inputs for pasture, etc. I’m absolutely up for developing the comparison. If you’d like, post your e-mail address as a comment (I’ll delete it without it showing up on the blog) and I’ll reply. Your ideas are most welcome. Reading is a valuable skill …

  3. I would love to see this fleshed out and compared to other foods. do you have any that can be looked up?

    when you say 209 square feet producing 12 ounces / day for 260 days, do you mean producing this much meat per year?

    how much land do you estimate it would take to produce a reasonable amount of meat, vegetables and fruit per person? i know little about farming so whatever fruits, greens, and meats would take up the least amount land, oil and labor to cultivate. i can probably find the latter from other sources, but its been hard so far, even with wheat. maybe i just dont know what to google. even vegetarians are little help with this. even just a breakdown of the meat side (properly pasture raised and treated of course) would be great.

    I dont eat grains either but im also curious about the comparison with wheat.

  4. Thank you, pixelfairy -

    I can find some information for the comparisons you mention. This is a point that I want to “flesh out” (I like it!). Feel free to ask questions!

    What this example suggests is that a piece of ground 209 ft x 209 ft could provide the complete protein needs of someone for 209 days, given the assumptions I stated.

    More than 160 years of information gathered by scientists and physicians from around the world strongly suggests that vegetables and fruits are luxury items in the human diet, so I don’t know what a reasonable amount would be. No vegetable or fruit (or cereal or legume) crop can meet the nutritional needs of humans as the sole component of their diet. They would have to be combined with at least one other feedstuff. It is possible for humans to survive on a purely animal product diet.

    Land that is producing fruits (or nuts) and vegetables can also produce animal products. Animals can be fed vegetable waste, either by-products from processing plants or plant material left in the fields after harvest. Animals can graze in orchards. The expression “crazier than a peach orchard boar,” while obscure, does illustrate this point (male pigs eating fermented windfall peaches become intoxicated …). Nancy and I are enjoying pork that was fattened on hazelnuts. Other producers run pigs in oak groves to eat acorns.

    Any perennial crop will require less energy than an annual, due to less cultivation. The reduction would depend on how frequently the perennial crop needs to be re-established (perennial crops don’t last indefinitely). Also, when the animals do the harvesting (grazing), less energy is needed than if the crop needs to be mechanically harvested.


    Pete B

  5. no single animal product can sustain humans either. it should be noted that you also need to eat skin and organs if you dont eat plants.

    what im interested in is a few examples. maybe apples and oranges differ wildly in thier resource and cultivation needs compared to pasture raised bison. but as a layperson, i would guess that the only significant difference between oranges and apples is that oranges favor more warm and humid climates (california, and florida if your in america for example) than apples, which seem to come from mid latitude to northern states. but bison and apples would be very different.

    my ex used to have a home vegetable and greens garden that she lived of except for meat and maybe milk. she claimed only a few square feet was enough per person and often had to give away large amounts of food despite having such a garden that was about 30 sq feet and included some herbs. if she and you are both right, we can all at least have vegetables and meat.

    of course, i doubt the economics of a backyard garden and commercial farm is simply a matter of scale.