Is the Grass Always Greener? Comparing the Environmental Impact of Conventional, Natural and Grass-Fed Beef Production Systems by Judith L. Capper
@ScienceBasedRD shared this on twitter, and I have a few quick observations...
First, the conclusion seems reasonable - that conventional beef is more resource efficient. While a unit of land under pasture may be less harmed, you get a lot less beef from it. It just takes a lot longer for a grass finished cow to get to market weight - and that means more feed is needed for daily maintenance (the calories all animals burn just to stay alive, move around, etc) plus more waste over the animal's lifetime.
However, modeling is not easy. The more variables you add the greater the chance that there will be errors. Thankfully modeling environmental impact of cows is not quite as difficult as modeling global climate change, but it's still pretty hard. I'm not sure how accurate a model will be in telling you the actual impact of the different farming systems, especially if some of the model variables are based on assumptions rather than data.
As I go through the paper, the first thing that strikes me as odd is figure 2.1.2. Why include dairy for conventional and natural but not grass fed? There are grass fed dairies, so why leave them out? It seems like an uneven comparison. The methods say "As dairy calves entering the beef system are characteristically finished within feedlots and cull dairy cows would not be eligible to be sold as grass-fed beef, the GFD system did not include any animals from the dairy industry." But that doesn't include existing grassfed dairies. It would be nice to see the results with grassfed dairies too so we can see what happens. Perhaps if grassfed added dairies that would help even the balance.
There are other aspects that were included that surely favor the grass fed farms. According to the methods, Jude included not only pesticide and fertilizer for feed production but even the impact of production of the pesticides and fertilizer. She also included average transport of animals for conventional and natural while grassfed was assumed to live on farm for their entire lives. But these are relatively small impacts compared to animal waste and water as far as I can tell.
When I get to the results (table 2) the first thing I notice is water use. It says that conventional uses 485,698 liters while grassfed uses 1,957,224 liters. Cows that live longer need to drink more water, sure, but this difference seems too wide. The huge difference is based on the assumption that 50% of pasture land in the grass fed system is irrigated. When that is changed to lower % irrigated the water use declines sharply: 25% 1,044,070, 15% 678,808, 5% 313,547. Irrigation for crops for grain finished cows "was calculated from application rates and proportions of crops irrigated according to the Census of Agriculture Ranch and Irrigation Survey".
Due to the differences in water use alone, I'm wondering what the environmental impact is per region of the country (or other countries, too). This information would be useful for consumers considering whether to "buy local" as well as for state governments, etc looking to make policy decisions. I'm surprised regional differences in water use isn't discussed.
Overall, the assumptions seem reasonable, except for perhaps for water use and the missing consideration of grass fed dairies. Overall, conventional beef does seem to be more efficient than natural or grassfed.
I have to add one thing that was not in the paper, one thing that proponents of animal ag do not like to think about - and even get very angry if you dare mention it!
Cows are not efficient at turning plants into meat. Even the most efficient animals still have to use part of their food to make bones and other in-edibles*, to move around, to heat their bodies, etc and make waste. Why loose so much energy through the animal when we can just eat the plants ourselves? Of course, we have to eat more grams of plant matter to get the same nutrition that we would get from meat, but the overall efficiency is still better, not to mention the health benefits of a diet rich in whole grains and veggies.
This is basic biology - higher trophic levels are less efficient than lower trophic levels. If we act as primary consumers rather than secondary consumers (at least some or most of the time) then the environment wins. Of course meat can be a healthy part of a balanced diet, but it's dangerous to assume that 200lbs yearly per person is a sustainable level of meat consumption, especially when we have developing countries hungry for more and more meat. We just don't have the land or the water (even if we assume the most efficient cows ever) to allow for all of the waste that comes with being a secondary consumer.
To me, the solution is to aim for production of animal products that is as efficient as possible (including consideration of the environment) but also to decrease overall meat consumption and/or move meat consumption to more efficient animals based on the land types that are available yet not better used for other functions. This will increase efficiency of the entire food system as well as improve biodiversity on farms (growing more diverse grains, etc instead of just cattle feed) and improve human diets.
* Yes, some of the in-edibles can be useful products. However, many have more efficient alternatives but the animal product is used just because it's a cheap byproduct of meat. Finding a use for byproducts might make the system more efficient, but we also need to look outside the system to see if other alternatives are actually more efficient.