Managing Enteric Methane Emissions for a Sustainable Dairy Sector
Cows, being ruminants, naturally produce methane as they digest food. This makes enteric methane one of the largest sources of greenhouse gas (GHG) emissions in the dairy sector. Farmers have several options available today to reduce these GHG emissions, such as improving feed quality and optimizing herd management practices. Additionally, innovative opportunities, including the use of feed additives and genetic selection, are being explored to further mitigate methane emissions in the future. These advancements will help the dairy industry continue to reduce its environmental impact and contribute to more sustainable agricultural practices.
Learning hub ▶ enteric methane
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Digital Resources
Summary Presentation
SPEAKER: Dr. Juan Tricarico, Dairy Management Inc.
Downloadable Resources
What Is Enteric Methane?
Enteric methane is the term given to methane produced by microbial digestion of feed in ruminants. Ruminants, like cows, digest their food through microbial fermentation. This fermentation primarily occurs in the rumen. One of the byproducts of this microbial process is methane, which is then eructated (burped) out into the air. Anywhere between 4-10% of the cow’s gross energy intake is lost as methane (Yan et al., 2000). Enteric methane is the single largest source of GHG emissions in the fluid milk chain.

KEY POINT
There are two basic ways to think about dairy GHG emissions:

Absolute Emissions
Total GHG emissions over a defined period of time

Emission Intensity
The volume of GHG emissions per unit of milk
Supply Chain Implications
To fully appreciate the benefits of emission reductions, we must consider the entire supply chain. When companies purchase raw materials, such as milk for food production, they also take on the associated emissions. This makes the intensity of supply chain emissions particularly significant. For a food manufacturer buying raw milk, the emissions burden linked to that milk becomes a crucial part of their overall environmental impact.
If a farm improves animal health:

Absolute Emissions
At the animal level, Absolute Emissions increase due to higher feed intake, increased milk production, and longer lives.

Emission Intensity
At the supply chain level, Emission Intensity may decrease due to improved productivity and a reduced need for replacement animals.
Factors that Influence Enteric Methane Production
Enteric fermentation is a natural biological process in ruminant animals. There are effective strategies to reduce enteric emissions while simultaneously promoting excellent cow health and enhancing productivity. These strategies are outlined below.

¹ Only a portion of strategies from Beauchemin et al. (2022) paper are represented in the chart.
² ↓ = small decrease (≤15%); ↓↓ = medium decrease (15–24%); ↓↓↓ = large decrease (≥25%); 0 = minimal or no change; ↑ = increase; ↑/↓ = variable results; ? = more research is needed.
³ ↑↑↑ = large increases; ↑ = small increases; 0 = minimal or no change; ↓ = decreases; ↑/↓ = increases in some emissions and decreases in others, or net CO₂ fixation, can occur; sources of other emissions: UPS = changes in upstream emissions of CO₂ from fossil fuels use or N₂O from application of fertilizers; ANI = increase in emissions of enteric N₂O; MAN = increase in emissions of manure CH₄ and N₂O.
⁴ ↑ = increase (of any magnitude); 0 = no change; ↑/↓ = variable results; ? = more research is needed.
Methane Mitigation Strategies
Increased Animal Productivity
Raising and maintaining healthy and productive cows is a great way to reduce enteric methane intensity. Intensifying animal production through better feeding, management, health, breeding, and reproductive performance increases methane emissions due to higher feed intake (Gerber et al., 2013). However, intensification also increases individual animal productivity, reducing the intensity of emissions. Taking steps to increase cow comfort, improve reproductive efficiency, and reduce disease are all options available to every farm.
Diet Reformulation
Diet formulation impacts cow digestion, from feed efficiency to passage rate. Certain ingredients in diet formulations like concentrates can decrease the intensity of enteric methane emissions due to their high digestibility. High-quality forage also increases the digestibility of the rations and promotes high productivity, reducing the amount of emissions per unit of milk. Diet changes should be balanced by a nutritionist to maintain a healthy rumen.
Examples of How Diet Reformulation Can Impact Enteric Emissions
-
Increasing Feed Intake and Concentrates: Increasing feed intake and the proportion of concentrate in ruminant diets are key strategies to reduce enteric methane emissions. Higher feed intake reduces the retention time of feed in the rumen, limiting microbial access to organic matter and thus decreasing rumen fermentation and methane yield. Concentrates increase dietary energy density, reduce structural carbohydrates, and lower rumen pH, which decreases methane production per unit of dry matter intake (DMI). Grain processing methods, such as steam-flaking corn, enhance starch fermentation, increasing propionate production as an alternative sink for metabolic hydrogen, thus reducing methanogenesis (Arndt et al., 2022).
-
Supplementing with Lipids: Supplementing diets with lipids, such as oils and oilseeds, also reduces methane emissions by inhibiting methanogens and protozoa, shifting rumen fermentation towards propionate production, and replacing fermentable carbohydrates. The effectiveness of lipid supplementation varies based on the type and amount of fat, and high lipid concentrations can decrease feed digestibility and increase methane emissions from manure (Patra et al., 2013). Byproducts are often a good source of lipids.
Related Practices Or Technologies
fermentation Modifiers
Feed additives that enhance production efficiency in dairy cows include substances like probiotics, prebiotics, oils, and ionophores. These additives can optimize nutrient absorption, improve gut health, and enhance milk production, improving overall cow performance. As a secondary benefit, many of these additives can reduce enteric methane emissions by altering the microbial fermentation processes in the rumen. By increasing production efficiency, they minimize emission intensity—lowering the amount of methane emitted per unit of milk produced, thus contributing to more sustainable dairy farming.
Examples of Feed Additives that Improve Efficiency
-
Ionophores: Ionophores (e.g., Rumensin®) improve feed conversion efficiency and milk yield by selectively targeting rumen microbes. As a secondary benefit, many of these additives can reduce enteric methane emissions by altering the microbial fermentation processes in the rumen. Monensin, commonly used in feedlot cattle production, has a small effect on methane production, reducing it by 3.6% in dairy cows (Appuhamy et al., 2013). It also improves feed conversion efficiency, reducing greenhouse gas emissions from feed production (Duffield et al., 2008b).
-
Essential Oils: Essential oils (e.g., Agolin Ruminant® and Mootral®) are volatile oils that give plants and spices their specific odors and colors. Some can negatively affect gram-positive bacteria and protozoa cell membranes, which produce hydrogen. While some essential oils have been shown to decrease methane production in vitro (Cobellis et al., 2016), results from in vivo studies have been far less conclusive (Benchaar and Greathead, 2011; Hristov et al., 2022).
-
Tannins: Tannins (e.g., Silvafeed®) are polymerized polyphenolic compounds that combine with proteins to form leather-like, indigestible substances. Tannins and tannin extracts inhibit fiber digestion and can reduce rumen hydrogen and methane production. However, high concentrations of tannins can negatively affect nutrient digestibility and animal health. (Jayanegara et al., 2012).
Related Practices Or Technologies
Methane Inhibitors
Some feed additives are specifically designed to reduce methane emissions. Additives are intended to reduce methane production in the rumen, not to provide nutrition. In general, additives work to inhibit or compete with the production of methane in the rumen. They can be added to diets and take effect quickly.
Always confirm that an additive is authorized and registered to mitigate methane emissions before feeding it for that purpose.
Examples of Methane Inhibitors that Impede Methane Production:
-
3-Nitroxypropanol/3-NOP (Approved for Use in the U.S.)
3-NOP (e.g., Bovaer®) inhibits the enzyme that catalyzes the last step involved with making methane to reduce enteric methane by 30% with no apparent side effects (Kim et al., 2020). -
Red Algae Seaweed/Halogens (Not Approved for Use in the U.S.)
Specific types of red algae seaweed (e.g., Brominata) naturally accumulate halogens such as bromoform and chloroform that prevent the final step in methane production. Red algae seaweed has reduced enteric methane by 50% but may also reduce fiber digestion and milk production. Red algae seaweed can accumulate iodine and heavy metals, a potential animal and human safety risk (Abbott et al., 2020). -
Nitrate (Not Approved for Use in the U.S.)
Nitrate is converted to ammonium to reduce free hydrogen, which would otherwise be used for methane production. Nitrate can reduce enteric methane by 15%. Nitrate is not approved for use in U.S. dairies because nitrite is a toxic intermediate that impedes oxygen transport to body tissues (Lee & Beauchemin, 2014).
Related Practices Or Technologies
Reducing Enteric Methane via Genetics
Genetic selection is a long-term option for reducing methane emissions. It involves selecting for low-methane-producing animals, similar to how farmers selected for high-producing animals in the past.
Research is ongoing to find genomic indicators for low-methane-emitting cows. Someday, methane emission may be part of the selection indexes. The timing depends on the research needed to develop the genetic trait and the demand from the marketplace. Although genetic improvement through animal selection is a long process, it offers incremental and permanent improvement potential (Manzanilla-Pech et al., 2021).
Learn More
Please note that we cannot confirm the accuracy or reliability of the materials found on external websites linked here.
Digital Resources
Summary Presentation
SPEAKER : Dr. Juan Tricarico, Dairy Management Inc

What is enteric methane?
Enteric methane is the term given to methane produced by microbial digestion of feed in ruminants. Ruminants, like cows, digest their food through microbial fermentation. This fermentation primarily occurs in the rumen. One of the by-products of this microbial process is methane, which is then eructated (burped) out into the air. Anywhere between 4 to 10% of the cow’s gross energy intake is lost as methane (Yan et al., 2000). Enteric methane is the single largest source of greenhouse gas (GHG) emissions in the fluid milk chain.

KEY POINT
There are two basic ways to think about dairy greenhouse emissions...

Absolute Emission
Total GHG emission over a defined period of time

Emission Intensity
The volume of GHG emissions per unit of Milk
Supply Chain Thinking is Key...
To fully appreciate the benefits of emission reductions, we must consider the entire supply chain. When companies purchase raw materials, such as milk for food production, they also take on the associated emissions. This makes the intensity of supply chain emissions particularly significant. For a food manufacturer buying raw milk, the emissions burden linked to that milk becomes a crucial part of their overall environmental impact.
If a farm improves animal health...

At the animal level
Absolute Emissions increase due to higher feed intake, increased milk production and longer lives.

At the supply chain level
Emission Intensity may decrease due to improved productivity and a reduced need for replacement animals.
Factors that Influence Enteric Methane Production
Enteric fermentation is a natural biological process in ruminant animals. There are effective strategies to reduce enteric emissions while simultaneously promoting excellent cow health and enhancing productivity. These strategies are outlined below.

¹ Only a portion of strategies from Beauchemin et al. (2022) paper are represented in the chart.
² ↓ = small decrease (≤15%); ↓↓ = medium decrease (15–24%); ↓↓↓ = large decrease (≥25%); 0 = minimal or no change; ↑ = increase; ↑/↓ = variable results; ? = more research is needed.
³ ↑↑↑ = large increases; ↑ = small increases; 0 = minimal or no change; ↓ = decreases; ↑/↓ = increases in some emissions and decreases in others, or net CO2 fixation, can occur; sources of other emissions: UPS = changes in upstream emissions of CO2 from fossil fuels use or N2O from application of fertilizers; ANI = increase in emissions of enteric N2O; MAN = increase in emissions of manure CH4 and N2O.
⁴ ↑ = increase (of any magnitude); 0 = no change; ↑/↓ = variable results; ? = more research is needed.
Methane Mitigation Strategies
Increased Animal Productivity
Raising and maintaining healthy and productive cows is a great way to reduce enteric methane intensity. Intensifying animal production through better feeding, management, health, breeding, and reproductive performance increases methane (CH4) emissions due to higher feed intake (Gerber et al., 2013). However, intensification also increases individual animal productivity, reducing the intensity of emissions. Taking steps to increase cow comfort, improve reproductive efficiency, and reduce disease are all options available to every farm.
Diet Reformulation
Diet formulation impacts cow digestion, from feed efficiency to passage rate. Certain ingredients in diet formulations like concentrates can decrease the intensity of enteric methane emissions due to their high digestibility. High-quality forage also increases the digestibility of the rations and promotes high productivity, reducing the amount of emissions per unit of milk. Diet changes should be balanced by a nutritionist to maintain a healthy rumen.
Examples of How Diet Reformulation Can Impact Enteric Emissions
Increasing Feed Intake and Concentrates
-
Increasing feed intake and the proportion of concentrate in ruminant diets are key strategies to reduce enteric methane emissions. Higher feed intake reduces the retention time of feed in the rumen, limiting microbial access to organic matter and thus decreasing rumen fermentation and methane yield. Concentrates increase dietary energy density, reduce structural carbohydrates, and lower rumen pH, which decreases methane production per unit of dry matter intake (DMI). Grain processing methods, such as steam-flaking corn, enhance starch fermentation, increasing propionate production as an alternative sink for metabolic hydrogen, thus reducing methanogenesis (Arndt et al., 2022).
Supplementing with Lipids
-
Supplementing diets with lipids, such as oils and oilseeds, also reduces CH4 emissions by inhibiting methanogens and protozoa, shifting rumen fermentation towards propionate production, and replacing fermentable carbohydrates. The effectiveness of lipid supplementation varies based on the type and amount of fat, and high lipid concentrations can decrease feed digestibility and increase CH4 emissions from manure (Patra et al., 2013). Byproducts are often a good source of lipids.
Methane Modifiers
Feed additives that enhance production efficiency in dairy cows include substances like probiotics, prebiotics, oils, and ionophores. These additives can optimize nutrient absorption, improve gut health, and enhance milk production, improving overall cow performance. As a secondary benefit, many of these additives can reduce enteric methane emissions by altering the microbial fermentation processes in the rumen. By increasing production efficiency, they minimize emission intensity—lowering the amount of methane emitted per unit of milk produced, thus contributing to more sustainable dairy farming.
Examples of Feed Additives that Improve Efficiency
Ionophores
-
(e.g., Rumensin®) improve feed conversion efficiency and milk yield by selectively targeting rumen microbes. As a secondary benefit, many of these additives can reduce enteric methane emissions by altering the microbial fermentation processes in the rumen. Monensin, commonly used in feedlot cattle production, has a small effect on methane production, reducing it by 3.6% in dairy cows (Appuhamy et al., 2013). It also improves feed conversion efficiency, reducing greenhouse gas emissions from feed production (Duffield et al., 2008b).
Essential oils
-
(e.g., Agolin Ruminant® and Mootral®) are volatile oils that give plants and spices their specific odors and colors. Some can negatively affect gram-positive bacteria and protozoa cell membranes, which produce hydrogen. While some essential oils have been shown to decrease CH4 production in vitro (Cobellis et al., 2016), results from in vivo studies have been far less conclusive (Benchaar and Greathead, 2011; Hristov et al., 2022).
Tannins
-
(e.g., Silvafeed®) are polymerized polyphenolic compounds that combine with proteins to form leather-like, indigestible substances. Tannins and tannin extracts inhibit fiber digestion and can reduce rumen hydrogen and methane production. However, high concentrations of tannins can negatively affect nutrient digestibility and animal health. (Jayanegara et al., 2012)
Related Practices Or Technologies
Methane Inhibitors
Some feed additives are specifically designed to reduce methane emissions. Additives are intended to reduce methane production in the rumen, not to provide nutrition. In general, additives work to inhibit or compete with the production of methane in the rumen. They can be added to diets and take effect quickly.
Always confirm that an additive is authorized and registered to mitigate methane emissions before feeding it for that purpose.
Examples of Methane Inhibitors that Impede Methane Production
3-Nitroxypropanol/3-NOP (e.g., Bovaer®): Approved for Use in the U.S.
-
3-NOP Inhibits the enzyme that catalyzes the last step involved with making methane to reduce enteric methane by 30% with no apparent side effects (Kim et al., 2020)
Red Algae Seaweed/Halogens (e.g., Brominata): Not approved for use in the U.S.
-
Specific types of red algae seaweed naturally accumulate halogens such as bromoform and chloroform that prevent the final step in methane production. Red algae seaweed has reduced enteric methane by 50% but may also reduce fiber digestion and milk production. Red algae seaweed can accumulate iodine and heavy metals, a potential animal and human safety risk (Abbott et al., 2020).
Nitrate: Not approved for use in the U.S.
-
Nitrate (NO3) is converted to ammonium (NH4) to reduce free hydrogen (H), which would otherwise be used for methane (CH4) production. Nitrate can reduce enteric methane by 15%. Nitrate is not approved for use in U.S. dairies because nitrite (NO2) is a toxic intermediate that impedes oxygen transport to body tissues (Lee and Beauchemin, 2014)
Related Practices Or Technologies
Reducing Enteric Methane via Genetics
Genetic selection is a long-term option for reducing methane emissions. It involves selecting for low-methane-producing animals, similar to how farmers selected for high-producing animals in the past.
Research is ongoing to find genomic indicators for low-methane-emitting cows. Someday, methane emission may be part of the selection indexes. The timing depends on the research needed to develop the genetic trait and the demand from the marketplace. Although genetic improvement through animal selection is a long process, it offers incremental and permanent improvement potential (Manzanilla-Pech et al., 2021).
Learn More
Please note that we cannot confirm the accuracy or reliability of the materials found on external websites linked here.
References
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