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California has established aggressive world-leading targets (SB 1383 [Lara 2016]) for reducing methane from dairy and other livestock (primarily beef cattle) sectors by 2030.


Methane, a potent greenhouse gas, is released into the atmosphere through the natural digestion process in cows. Fermentation occurring in the cow's rumen leads to cows belching methane. The process allows the animal to consume and utilize fibrous feeds and agricultural byproducts that can't be digested by humans.

Researchers are experimenting with supplementing the feed of high-performing dairy cows with additives, ranging from seaweed to garlic, to improve milk production and reduce environmental emissions from dairy farms. 

The adoption of methane-reducing feed additives will soon provide an added boost to the industry's highly successful manure methane reduction efforts. Leading California universities, such as UC Davis and UC Berkeley are spearheading efforts that could soon result in feed additives or other interventions capable of reducing enteric methane by 30 percent or more. Some additives have shown potential in initial research to reduce emissions by nearly 90 percent. 

Given the long list of potential solutions and the long checklist of requirements to ensure effectiveness without negative unintended consequences, rigorous research is key. Solutions must be safe for animals and people, acceptable to consumers, capable of being included in daily rations, and economically viable. The CDFA has been working hard to keep up with the “the state of science,” so they can help to fill gaps as they administer the new 2023 Livestock Enteric Methane Emission Reduction Research Program (LEMER-RP). The California Budget Act of 2022 provided $10 million to fund demonstration trials to evaluate additives and dietary modifications that have the potential to reduce enteric methane emissions in the dairy and livestock sectors.

State and federal agencies play several important roles in preparing for  widespread adoption of such strategies, especially since the beef and dairy industries are highly regulated to ensure quality and food safety. Government can also assist with offsetting adoption costs through incentive funding, as California is now aiming to do.  The EDF believes that incentivizing farmers and financing implementation is an area where all parties can work together: government, food and beverage companies, philanthropists, and other private investors. Verifying and accounting for emission reductions is critical in making this possible. 

Dairy Cares, with support from the California Dairy Research Foundation, Nestlé, Starbucks, and California Dairies, Inc., has been coordinating an effort to utilize expertise from VERRA and leading researchers in developing a protocol and calculator for the California Air Resource Board (CARB)’s consideration. Creation of a CARB-approved calculator will provide a highly-credible way to monetize reductions achieved through voluntary adoption. It will also allow for verification of emission reductions within the supply chain.

Global food and beverage companies are acknowledging methane-reducing feed additives as a significant opportunity to invest in emission reductions within their supply chain (insetting). 


As the California Air Resources Board's Analysis of Progress report correctly concludes, no single livestock methane reduction action can achieve the targeted reductions. Achieving the state’s targeted reductions requires a coordinated, comprehensive approach involving continued efficiency (fewer cows), methane avoidance, methane capture and utilization, as well as enteric methane reduction activities. Ongoing research is also important as we seek to identify, implement, and verify cost-effective enteric and other reduction strategies.

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Enteric Methane Reduction  

Producing more milk with fewer cows greatly reduces the carbon intensity of milk production. After a period of rapid herd growth in California between 1980 and 2008, the number of cows in California has steadily declined from 1.885 million milk cows in 2008 to 1.688 million in 2022, according to the United State Department of Agriculture (USDA)'s most recent Census of Agriculture (2017-2022). This herd attrition has already accounted for approximately 2 million metric tons of CO2e reduction, including about 900,000 metric tons of enteric emissions from the state’s dairy sector (a roughly 10% decrease). Continued and likely accelerated attrition will lead to an estimated additional 1 MMT CO2e reduction by 2030, or a total of approximately 3 million metric tons.

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Fewer Cows Since 2008


Over the past 50-plus years, California dairy production has undergone significant advancement, including advanced nutrition, improved animal care and welfare, breeding practices, as well as overall feed crop production efficiency.

According to research published in the Journal of Dairy Science, the climate footprint of milk production in California has been significantly reduced over the past 50 years (1964 to 2014). Scientists at the University of California, Davis conducted a life cycle environmental assessment (cradle to farm gate) of California dairy farm production, using the latest scientific models and international research standards.

“The study documents the productivity, efficiency, and overall sustainability of milk production in California and the critical role dairy cows play in regenerative agricultural practices and sustainable food systems,” said Dr. Ermias Kebreab, Professor at UC Davis and Sesnon Endowed Chair, who led graduate student Anna Naranjo in completing the research project.

The study’s key findings include:

  • The amount of greenhouse gas emissions per each unit of milk (e.g. glass or gallon) produced has decreased more than 45 percent, due to increased milk production efficiency, including improved reproductive efficiency, nutrition, comfort, and overall management.

  • The amount of water used per unit of milk produced has decreased more than 88 percent, primarily due to improved feed crop production and water use efficiency.

  • Dramatically improved feed crop production and utilization of agricultural byproducts have led to significant reductions in the amount of natural resources used to produce each unit of milk, including, land, water, fossil fuels, pesticides and energy.

As the study documents, more than 40 percent of dairy feed ingredients in California are byproducts of other agricultural and food production processes, such as almond hulls, citrus and tomato pulp, culled carrots and other similar products that are not suited for human consumption but make healthy, nutritious feed for cattle. As a result, nearly half of the feed needed to produce California milk—which represents about 20 percent of all U.S. milk—is being provided without a single drop of additional water. Dairy cows are efficient recyclers, making use of food and agricultural byproducts that are either indigestible or undesirable for humans and avoiding the need to landfill or otherwise dispose of these materials.


The study shows that California's dairy farm families are producing milk more efficiently and sustainably, minimizing their climate footprint in the process. While there is always more work to be done, the findings show a significant overall improvement in environmental performance, producing more wholesome, nutritious milk and dairy products with fewer natural resources, less water, less energy, and fewer fossil fuels.

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Click here to read the full summary about California's comprehensive approach to methane reduction.

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Dairy Cares
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