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Stanley, P. L., J. E. Rowntree, D. K. Beede, M. S. DeLonge, and M. W. Hamm. 2018. Impacts of soil carbon sequestration on life cycle greenhouse gas emissions in Midwestern USA beef finishing systems. Agricultural Systems 162:249-258.
The 411 on Beef
Beef is a top commodity in the United States. A lucrative industry, cattle brought in almost $44 billion dollars in 2016. As demand for beef products has increased in the past few decades, a shift in the amount and type of cattle production followed. Instead of being raised on large swaths of agricultural land, most cattle in the United States are now finished on a feedlot – that is, a concentrated animal feeding operation. The switch to feedlots allows more cattle per operation, while feeding them with a specialized diet of corn and corn byproducts. This diet allows cattle to gain weight faster, bringing them to their finished weight quicker than cattle who are finished on grassland.
Corn vs Grass
In recent years, there has been an increase in consumers who demand grass-fed beef. Whether for animal rights or health purposes, this demand requires more cattle to fed on grassland until they reach finishing weight. In response to this change in demand, some studies have shown that grass fed beef, while potentially more beneficial to the animal, is actually worse for the environment in terms of greenhouse gas emissions. When considering a grass-finished cow versus a feedlot-finished cow, there are some notable differences. Grass fed cows are, frankly, alive for a longer period. They require more resources, such as food and water, to stay alive than feedlot cows do. Further, grass and other plants are very high in fiber. For cows who graze on these plants, the excess fiber can lead to a higher amount of “enteric emissions” – cow burps, and “manure emissions” – cow farts. Though this may sound like no big deal, enteric and manure emissions from cattle account for 20% of the total methane (CH4) released into the atmosphere, and 1.5% of the total greenhouse gas emissions. Lastly, cows who are fed on grass for their lifetime require large amounts of grazing land – about 1.5 acres for one cow-calf pair per year. Open pastureland can act as a carbon sink, meaning it can absorb carbon that is put into the atmosphere. However, if cows are grazing on grassland that is unmanaged, the land can become overgrazed and its ability to absorb carbon is largely diminished.
Land Management and Cattle Production
Does this mean feedlot-finished beef is the better choice when considering the environment? Maybe. However, some new evidence may clear this up. A group of researchers led by Paige Stanley from Michigan State University conducted a study comparing greenhouse gas emissions from feedlot-finished cattle and grass-finished cattle on grasslands that were managed through adaptive multi-paddock grazing (AMP). Essentially, AMP grazing provides a chance for grasslands to recover after short periods of grazing by cattle. The cattle are rotated through “paddocks”, or different pasturelands, for a finite period in each one. They are moved before the pasture becomes overgrazed so the vegetation can regrow. This allows the land to act as a carbon sink, sequestering carbon in the soil and reducing greenhouse gases in the atmosphere. The results of this study show that although grass-finished cattle do produce more greenhouse gas emissions than feedlot-finished cattle, (9.62 kg CO2-e kg CW -1 vs 6.09 kg CO2-e kg CW -1 respectively), when considering the amount of greenhouse gases the AMP managed grasslands can sequester, the net emissions for grass-finished cattle is -6.65 kg CO2-e kg CW -1 which is considerably less than the 6.09 kg CO2-e kg CW -1 net emissions from the feedlot-finished cattle.
Squash the Beef (Demand)
So why not make the total switch to AMP grazing? Well, the answer is simple. AMP grazing requires a lot of land, more land than can produce the amount of beef that is in demand from the U.S. For those farms that produce grass-fed beef, switching to AMP grazing will undoubtedly decrease their environmental impact. Until the demand for beef production decreases, high greenhouse gas emissions will be the reality of the cattle industry.