A recent study by California researchers determined that pasture-finished cattle produced more emissions and had a higher carbon footprint than grain-finished cattle.
The study, titled “Carbon opportunity cost increases carbon footprint advantage of grain-finished beef,” appeared in the Dec. 13 issue of PLOS One and assessed the carbon footprint of 100 beef production systems in 16 countries. The study also looked at the carbon opportunity cost of each system, which is the potential carbon sequestration that could occur on land if it were not in production.
The study’s abstract noted that most life-cycle assessments comparing beef production systems and their carbon footprint have been limited to production emissions, and do not include potential carbon sequestration from grazing and alternate uses of land used for production.
For the study, researchers conducted a comparison between pasture-finished operations where cattle almost exclusively consumed grasses and forages, and grain-finished operations where cattle first grazed and then were finished on a grain diet.
The researchers found that pastured-finished cattle produced 20% more emissions and had a 42% higher carbon footprint than grain-fed cattle.
The study also found that on average, the opportunity cost of operations was 130% larger than production emissions. “These results point to the importance of accounting for carbon opportunity cost in assessing the sustainability of beef production systems and developing climate mitigation strategies,” the abstract read.
Study findings
According to the study authors, about one-third of cattle globally are raised on pasture-finished systems. Grain-finished systems account for 15% of global systems, and other systems (such as mixed crop-livestock production) account for the remainder systems.
The study found that pasture-finished systems have higher average production emissions, as grain-fed cattle typically have higher growth rates.
“As a result, proportionally less energy is expended on maintenance rather than growth, such that inputs and emissions per unit of beef is lower,” the study read.
In addition, the study noted that beef’s carbon footprint is influenced by land use, and pasture-finished systems have a higher land-use intensity on average. This is because the amount of pasture needed in the finishing stage of pasture-raised systems is larger than the amount of cropland needed to provide grain for grain-finished systems, the authors said.
Calculations
The carbon footprint, which is the sum of production emissions, soil carbon sequestration and opportunity cost, was calculated on 100 beef production operations across 16 countries. The study included both beef and dairy herds.
The data was drawn from a dataset of food and beverage life-cycle assessments, and a study assessing the impacts of soil sequestration on emissions in Midwestern beef finishing systems.
The California study conducted a pairwise comparison—a process of comparing entities in pairs to determine which is preferred—between the two types of finishing systems. Additionally, the researchers conducted a regression analysis of the relationship between land-use intensity and carbon footprint.
Production emissions represent emissions associated with enteric fermentation, housing, manure management and feed production inputs (such as fertilizers, pesticides and machinery). Land-use intensity represents land required for grazing and crop production.
Soil carbon sequestration was calculated as the product of land-use intensity of grazing and carbon sequestration due to grazing. There is not a specific carbon sequestration rate for each life-cycle assessment location due to environmental and management factors, so a mean carbon sequestration rate for “improved grazing management” was used.
“To be conservative in our carbon footprint for grain-finished operations, we assume that no carbon sequestration occurs on cropland used for feed production, consistent with research that shows that CO2 emissions from agricultural land are generally balanced by removals,” the study read.
The carbon opportunity cost calculated how much carbon sequestration would have occurred if land was occupied with native ecosystems instead of pasture and cropland.
The study authors noted that their results are not intended to be globally representative of all operations, as all areas of the globe were not included in the data.
“Our conclusion that beef operations with low land-use intensity, including grain-finished operations, have lower carbon footprints than pasture-finished operations and others with high land-use intensity provides important insights for agricultural stakeholders globally such as in Brazil where pasture expansion is a leading driver of forest loss,” the study said.
Including products’ carbon opportunity cost, not just production emissions or soil carbon sequestration, could shift which production systems are incentivized by government programs, corporate procurement, investors and consumers, the authors concluded. — Anna Miller, WLJ managing editor
