Does grass-fed beef really have a larger carbon footprint than its corn-fed cousin? That’s the controversial claim made by John Stossel, posted on Townhall.com and televised on Fox Business Network, that I talked about in my post from earlier this week. With a little digging, it turned out that the so-called “research” on which the story was based (posted here by its WSU co-author) turned out not to be science at all, but rather a wanly disguised shill job by Elanco, the company that makes the dietary supplements that corn-fed cattle require, with precisely zero supporting data or calculations. However, while such inconvenient facts may impugn the credibility of both the source and Mr Stossel’s shoddy reporting of it, they don’t necessarily invalidate the conclusion that concentrated feedlot finishing is less resource-intensive than grazing on pasture.
While that conclusion may at first sound counter-intuitive, it has a reasonable economic rationale: Feedlot-finishing produces animals that get much fatter (corn-fed carcass weights are about 30% heavier), at a much faster rate (corn-fed steer can gain the same weight in about half the time), than the pasture-based alternative. Thus (the argument goes), in order to produce the equivalent amount of beef, corn-based finishing systems produce far fewer methane emissions, simply because an animal that lives half as long tends to poop half as much, and poop is what introduces methane into the atmosphere. While I may have serious reservations about its source, I try not to accept or reject a potentially important hypothesis without supporting evidence, and the underlying reasoning here seems sufficiently solid to warrant a deeper investigation of the whole grass v. corn docket.
As it seems so often to be the case in the real world, the more I ask a question, the more complicated the answers become; do any real research, and you’ll quickly convince yourself that it would take a small (or possibly large) book to go through all the arguments in grass v. corn in detail. But that doesn’t mean there aren’t some particular issues, and even a few reasonably clear answers, that seem fundamental to this particular argument, and which I’ve tried to summarize as succinctly as possible, subject to some minimum standards for accuracy and completeness (I’d like to think that, in writing a post like this, we at the Proximal Kitchen hold ourselves to a smidge higher bar than did Prof Capper and Mr Stossel in theirs):

1. Energy Inputs: For the grass-fed steer, energy inputs are largely related to the production and/or transportation of hay for feeding; the feedlot-finished steer requires corn for feeding (which in turn requires fertilizer to grow, and transport to deliver) as well as energy for transport of the animal itself over generally longer distances. The Capper/Elanco paper claims to adjust for fertilizer and transport, but neither the underlying assumptions, the related calculations, nor the final outputs are provided, so it’s hard even to guess at what numbers they’re using in their final calculations, but I did find one example of an actual calculation (posted here by some Bard college grad students, although I’m not sure how good their numbers are), as well as the abstract of a more serious academic study (link here), that make a  pretty compelling case that grass-fed beef requires far less energy, purely from an input perspective. A contrary view – in which the feed and transport requirements of raising beef on pasture in colder climates (i.e., when the herd can’t simply convert solar energy into food via grass) dominate the energy intensity of the corn-based CAFO – may be found here.
2. Methane Emissions: It seems reasonably clear that pasture-raised beef produces higher methane emissions, for the reason already stated: They live a lot longer, so they spend a lot more time excreting methane into the environment. How this nets down against energy inputs, of course, is less clear, because the cumulative energy-input equation (per bullet 1. above) is less well-understood. There is also a residual issue that may be important, but that I don’t generally see discussed in the literature: Feedlot operations must dispose of essentially all of the excrement from the cattle, so virtually all of it goes directly into the atmosphere, without any offsetting credit. But in a pasture, virtually all of the waste product ends up back in the ground as fertilized soil. How this effect nets down the effective emission footprint is unclear, at least to me.
3. Land & Water Use: There are strong arguments that CAFO operations are more efficient from an acreage perspective, simply by virtue of their concentration: Fattening animals more quickly on less land almost has to use less total acreage. However, there is a closely related argument about the nature of the soil use: The feedlot operation essentially destroys the dirt it sits on for other applications, creates potential groundwater problems, and almost surely causes profound soil erosion. Similarly, in the case of water, the longer feeding times on pasture generally imply much higher water requirements; however, the feedlot will likely create more water pollution, and consumes water transitively through the corn diet. So, while the feedlot operation almost surely requires less land and water directly to produce a kilogram of beef, the nature of that usage is much more destructive to the land, and possibly to water, as a resource, and therefore has additional opportunity costs that are not generally accounted for, at least in my review of the literature.
4. Health Claims: The Fox/Stossel pieces (although not the Capper/Elanco presentation) also make some rather silly claims to the effect that there are no demonstrable health differences. This, I think, is just willful ignorance: We can debate the unknown impact of antibiotics (resistance), or perhaps dodgy feedstock (um, mad cow, anyone?), but the lower overall fat and superior lipid profile of grass-fed beef is, in my view, pretty uncontroversial.
5. Technology and Breed: As near as I can tell, all the available research on grass v. corn compares a modern, state-of-the-art feedlot operation to relatively more primitive pasture-raised technologies. If both of those represent the best technologies available, then that is fair enough, but that is not an inherent truism, for at least two reasons: First, and most importantly, feeding on grass requires cows that are naturally suited to a grass-based diet. That seems obvious enough, but generations of culling and breeding the herd specifically for feedlots has left us with very few cows that are at their best on grass: We have literally bred the ability to feed on grass out of the animal. That may or may not be a good thing, but it certainly introduces a bias into the studies, because they’re implicitly comparing the most efficient corn-fed animal with the least-efficient grass-fed animal. Furthermore, there is a new technique – “managed intensive grazing” – that appears to make grass feeding much more efficient with very little extra toll (and possibly some benefit, due to a natural grazing/fertilizing cycle) on the environment; possibly, these techniques are even as land-efficient as CAFOs, although I could only find one discussion (here, from Mother Earth, not exactly an unbiased or scientific resource).
6. Other Negative Externalities: My biggest gripe with the data provided in support of CAFOs is that, in all likelihood, some of their biggest potential costs are simply unpriced – what economists call “negative externalities“, or costs borne by society that are not perceived by the person creating the cost. This phenomenon occurs all the time in our economy, but surely one the scariest examples is the potential for the use of antibiotics in CAFOs to encourage resistance, because it’s hard to imagine something more taken for granted and yet more fundamental to human longevity than antiobiotics. Some 70% of all antibiotic production in the US is consumed by meat and dairy production, and yet we have very little understanding of what their presence in our food system will mean for future bugs’ resistance to existing medicines. We know that antibiotics are becoming less effective; we do not know definitively why, but surely it is worth thinking about the single largest consumer of the stuff. There are also all sorts of other unpriced costs, including massive taxpayer-borne cleanup costs for the CAFO sites and their manure disposal mechanisms (by some estimates, in the many billions of dollars).

Well, I’ve probably burned up way too much of your and my time at this point, so I’ll summarize it as briefly as I can like this: If you think less flavorful, more richly marbled, corn-fed beef tastes better, I’m not about to stop you, but don’t kid yourself about the health costs. If you think that the higher cost of grass-fed beef is worth the flavor, health, and ethical benefits that eating it confers, then I’m with you, but I won’t make you do it. However, if you want to make an unequivocal case that feedlots are more environmentally sound than pastures, then you’ll have to do a considerably more careful job than Professor Capper, Elanco, John Stossel, and Fox Business News do. That’s not to say that “grass-fed” is the slam-dunk winner – there are reasonable arguments in favor of corn-feeding, from an efficiency point of view, and the grass-fed lobbies should both consider these arguments carefully, and make their own case more rigorously. But the overall balance of evidence suggests that it is grossly premature to render a verdict in favor of CAFOs, particularly when one considers factors such as the broad social costs to our soil and health, none of which are actually perceived by the feedlot operator.
Finally – and I say this as a meat-eater – it’s worth remembering that all beef production is incredibly inefficient from an energy point of view, because, it is hard to think of a more wasteful way to convert energy in to food than beef (c.f. this older but excellent, and prescient, piece by Prof Pimentel). That doesn’t mean we shouldn’t eat it; but it does mean that we should think about it a little more carefully than either Fox or Mother Earth.