Cows on Horsebarn Hill
Photo Credit: Milton Levin/UConn Photo
Scientific Frontline: Extended "At a Glance" Summary: Carbon Footprint of Dairy Production
The Core Concept: The carbon footprint of milk production measures the environmental impact, specifically carbon emissions, generated during the creation and delivery of dairy products.
Key Distinction/Mechanism: Unlike traditional Tier 1 life cycle assessments that use generalized equations, farm-specific Tier 2 equations factor in localized data, including non-lactating herd members, enteric fermentation, feed production, manure management, and dual-purpose (meat and dairy) cattle operations.
Major Frameworks/Components:
- Enteric fermentation (digestive processes) accounts for the largest portion of emissions (approximately 48%).
- Feed production, including fertilizer use, represents the second-largest emission source (24%).
- Manure management (20%) and farm energy use (8%) comprise the remaining primary emissions.
- Emission allocation must be adjusted for dual-purpose farms; in developing nations, only about 50% of farm emissions may be directly tied to milk production, compared to 90% in specialized US operations.
Branch of Science: Animal Science, Environmental Science, Agricultural Science, Climatology.
Future Application: Utilizing farm-specific data to identify low-emission practices that can be translated into targeted management strategies for other farmers, ultimately reducing the global environmental impact of agriculture.
Why It Matters: Increasing agricultural efficiency and per-animal productivity, particularly in developing nations, is demonstrated to be more effective at reducing the carbon footprint per kilogram of milk than focusing solely on emission mitigation strategies. Accurate measurement is critical as environmental impact becomes a determining factor in international commerce.
Every product or service has a “carbon footprint,” a measure of the environmental impact of creating or delivering it.
A new study from the lab of Elias Uddin, assistant professor of animal science in the College of Agriculture, Health and Natural Resources (CAHNR), determined a more accurate measure of the carbon footprint of milk produced in Bangladesh. This work was recently published in the Journal of Dairy Science.
The key data used in this study were collected from the Bangladesh Agricultural University Dairy Farm during 2018–2023. Uddin’s lab collaborated with researchers from Bangladesh Agricultural University on the study. They calculated emissions related to the cows’ diet, including fertilizer used to grow feed, enteric emissions produced by the cows’ digestive processes, and manure management. Enteric fermentation (digestion) accounted for 48% of emissions, followed by feed (24%), manure (20%), and energy used to run the farm (8%).
In accordance with standard life-cycle assessment (LCA) guidelines, the data included emissions related not only to lactating cows but also to non-lactating members of the herd. “You have to account for those non-lactating animals, because those are part of the production system,” Uddin says. “You cannot just avoid them because they don’t produce milk.”
This study did not include the emissions associated with the milk once it left the farm, because the researchers did not have access to data about how far the milk traveled and how it may have been processed after delivery.
On average, during the five-year period, the carbon footprint of milk on the farm was 5.18 kilograms per kilogram of milk. This is a measure of how many kilograms of carbon are required to produce one kilogram of milk.
Previous work has held that dairy production in Southeast Asia has a much higher carbon footprint than U.S. or European dairy farms. The carbon footprint of those farms is about 1 kg of carbon emissions per kilogram of milk.
This calculation is based on the fact that American and European cattle are much more productive; each cow produces an average of 30 to 40 liters of milk a day compared to cattle in developing countries like Bangladesh, which produce only 4 to 8 liters of milk daily.
However, this study demonstrated that using farm-specific data and the Tier 2 equations proposed by the Intergovernmental Panel on Climate Change (IPCC) resulted in a 27% lower carbon footprint of milk compared with previous estimates based on the more generalized Tier 1 equations.
Critically, the cows’ productivity increased by 63% over the five-year study period. This led to a 37% reduction in the carbon footprint over time. In 2018, the cows on the farm produced an average of 3.53 kilograms of milk per day. By 2023, they were producing 5.76 kilograms on average. The increase in productivity was due to genetic selection and improved management strategies, such as a balanced diet and more efficient feed management.
“We saw that increasing productivity is really a crucial thing, and very important to reduce the carbon footprint,” Uddin says. “In developing countries, increasing efficiency and productivity is key to reducing carbon footprint rather than hitting only emissions mitigation strategies.”
Another important factor is that in Bangladesh, cattle farms raise animals for both dairy and meat together (dual-purpose). In the U.S., these are usually separate operations. This means that using the same equation for both areas is not accurate. Only about 50% of emissions on a cattle farm in Bangladesh go toward milk production (called emission allocation), while in the U.S., this is closer to 90%.
This led the researchers to look at the carbon footprint per unit of nutrient production, such as the protein or calories for human consumption produced by the farm, which accounts for the nutrients provided by both meat and dairy. This put the Bangladeshi farm on much more similar ground to U.S. producers, allowing a fair comparison if necessary.
“If we use that traditional allocation method of emission, it overestimates emissions,” Uddin says. “But if we use the specific allocation method that is applicable for production system in Bangladesh, it really gives you a different answer.”
This work has impacts far beyond the specific farm used in this study. The carbon footprint varies significantly among farms, even within the same region. By looking closely at individual farms, as they did in this study, researchers can gain more informed insights and provide better recommendations for other farms.
“We can see which farms are doing better compared to others, and the farm that has a low footprint, the practices they’re doing, can those be translated into key messages that can be used by other farmers to make changes?” Uddin says.
Having accurate information about a product’s carbon footprint will be increasingly important as environmental concerns become a more dominant factor in international commerce.
“Let’s say two different countries are exporting the same product at a similar price,” Uddin says. “If one is more environmentally friendly than the other, importers are going to prefer the one that is environmentally friendly.”
Additional information: This work relates to CAHNR’s Strategic Vision area focused on Advancing Adaptation and Resilience in a Changing Climate.
Published in journal: Journal of Dairy Science
Authors: M.S. Bari, M.A. Islam, M.H. Rashid, and M.E. Uddin
Source/Credit: University of Connecticut | Anna Zarra Aldrich
Edited by: Scientific Frontline
Reference Number: env091626_02
