Diet Reformulation Strategies: Lipid Supplementation
alternative practice names:
Fat Supplementation
Dairy nutritionists often use dietary fats to increase ration energy density. Today’s high-performance U.S. dairy diets typically contain 2 to 3% rumen-available fats from forages and grains and another 1 to 2% from oilseeds and other feed ingredients, often approaching current maximum rumen unsaturated fatty acid load recommendations.
Supplemental dietary rumen available fats show promise as enteric methane mitigators for lactating dairy cows (de Ondarza et al., 2024). Rumen-available fats affect methane production in several ways:
Rumen-available fats are hydrogenated (e.g., have hydrogen added) in the rumen, reducing the amount of free hydrogen available for methane production.
Fats disrupt the cell membranes of fiber-digesting rumen microbes.
Fat supplementation with rumen-available fats can effectively reduce both absolute methane emissions (g/day) and methane emission intensity (g/kg fat-and-protein-corrected milk). Specific types of fats, such as polyunsaturated fatty acids (PUFAs) and medium-chain fatty acids (MCFAs), are especially effective at suppressing methane production. However, the efficacy of fat supplementation is influenced by the composition of the basal diet. High levels of rumen-available unsaturated fat in the diet can reduce fiber digestion, milkfat percentage, and overall productivity. Notably, high levels of unsaturated fatty acids in the rumen are associated with an increased risk of milk fat depression, potentially compromising overall dairy productivity.
When used, in what regions in the U.S. is the practice found:
Northwest, West, Upper Midwest, Southwest, Northeast, Southeast
FARM SIZE
When used, typically found on farms of the following sizes:
All Sizes

Practice Benefits
Production: Increasing dietary fat to provide more dietary energy can enhance dairy production and profits. However, care must be taken not to exceed rumen-available unsaturated fatty acid limits.

Implementation Insights
Site-specific or Farm-specific requirements

There are no site-specific or farm-specific requirements.
Required Capital Expenditures (CapEx)

There are no capital expenditures required.
Required Operational Expenditures (OpEx)

Feed formulation: Incorporating fats into the diet may require adjustments to other components to maintain overall balance, which can add to formulation costs. This includes ensuring that fiber digestion is not compromised and that the overall energy density of the diet is optimized.
Fats and lipids: Increasing the dietary inclusion of fats may raise feed costs. Furthermore, lipid prices can be volatile and contribute to potential cost fluctuations.
Implementation Considerations

Variability in enteric methane response: The response to supplemental fats in terms of reducing enteric emissions can be inconsistent. This variability is influenced by factors such as the specific type of fatty acids used, the basal diet composition, and the stage of lactation of the cows. Without precise prediction models, the effectiveness of fat supplementation as a methane mitigation strategy remains uncertain.
Impact on rumen function: Excessive fat levels, especially rumen-available fats, can negatively affect rumen fermentation, potentially leading to reduced fiber digestion and poor rumen function.
Negative impact on dairy performance: Supplementation with certain types of fats, particularly UFAs and PUFAs, can cause milk fat depression, reducing both milk fat percentage and yield. The degree of reduction can be significant, especially when the total dietary fat concentration exceeds the recommended limits. This negative impact on milk components could offset the environmental benefits achieved through methane reduction.
Complex dietary interactions: The effectiveness of fat supplementation is heavily influenced by interactions with other dietary components, such as rumen-degradable starch (RDS) and fiber digestibility. For instance, higher RDS levels in the diet may enhance the methane-reducing effects of certain fatty acids, but these interactions are complex and not fully understood.
Limitations in current models: Existing nutritional models may not accurately predict the outcomes of fat supplementation due to the non-linear and context-specific nature of its effects. This adds a layer of uncertainty for dairy nutritionists when formulating diets aimed at methane mitigation.
Financial Considerations and Revenue Streams
PROFIT POTENTIAL
The inclusion of fats in the diet may increase feed costs, and the prices of fat sources can be volatile, adding an economic risk to their use. Balancing the potential environmental benefits with cost-effectiveness is a key challenge for dairy producers.
Additional Resources

Environmental Impacts
REDUCES FARM GREENHOUSE GAS FOOTPRINT
Fat supplementation can moderately reduce enteric methane emissions of U.S. dairy cows.¹ These reductions are achieved by altering rumen fermentation processes, decreasing the activity of methane-producing archaea, and providing alternative hydrogen sinks. However, these benefits need to be balanced with potential impacts on milk production and overall cow health, as excessive fat supplementation can negatively affect fiber digestion and milk fat synthesis.² In addition, if rumen-available fat supplementation decreases fiber digestion, it has the potential to increase manure methane emissions. Therefore, this strategy must be considered in relation to herd management and manure management characteristics.
See research highlights below:
De Ondarza et al. (2024) found that supplementing dairy cow diets with rumen-available fats, particularly PUFAs and UFAs, can significantly reduce enteric emissions. Specifically, the study found that each percentage unit increase in rumen-available PUFA reduced CH₄ emissions by approximately 6.88%, while UFA reduced it by about 4.65%.
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¹ Many U.S. lactating dairy diets already provide significant amounts of rumen-available fat from typical feed ingredients. Opportunities for enteric CH₄ mitigation from additional rumen-available fatty acid supplementation still exist, but they must be balanced with the risk of potential negative effects on rumen function and productivity associated with excessive rumen-available fat levels (de Ondarza et al., 2024).
² Excessive fat supplementation, particularly with rumen-available fats, can reduce fiber digestibility and decrease milk fat percentage by 7.8% and milk fat yield by 6%, leading to a negative impact on overall milk production (de Ondarza et al., 2024).
REFerences

Alignment with FARM Program
FARM Environmental Stewardship (ES) V2-V3 Alignment
FARM ES uses information about rations to calculate GHG emissions intensity, including enteric methane. The platform focuses on the lactating herd ration, with the option to enter details on rations for other animal classes. FARM ES Version 3 has the ability to run custom "what-if" scenarios where users can change various inputs, including ration information, to determine the impact on farm emissions.
FARM Animal Care (AC) V5 Alignment
The FARM Animal Care program requires that all age groups of animals have consistent access to sufficient feed to support their maintenance, health, and growth.
Contents
We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights.
We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights.
Dairy nutritionists often use dietary fats to increase ration energy density. Today’s high-performance U.S. dairy diets typically contain 2 to 3% rumen-available fats from forages and grains and another 1 to 2% from oilseeds and other feed ingredients, often approaching current maximum rumen unsaturated fatty acid load recommendations.
Supplemental dietary rumen available fats show promise as enteric methane mitigators for lactating dairy cows (de Ondarza et al., 2024). Rumen-available fats affect methane production in several ways:
Rumen-available fats are hydrogenated (e.g., have hydrogen added) in the rumen, reducing the amount of free hydrogen available for methane production.
Fats disrupt the cell membranes of fiber-digesting rumen microbes.
Fat supplementation with rumen-available fats can effectively reduce both absolute methane emissions (g/day) and methane emission intensity (g/kg fat-and-protein-corrected milk). Specific types of fats, such as polyunsaturated fatty acids (PUFAs) and medium-chain fatty acids (MCFAs), are especially effective at suppressing methane production. However, the efficacy of fat supplementation is influenced by the composition of the basal diet. High levels of rumen-available unsaturated fat in the diet can reduce fiber digestion, milkfat percentage, and overall productivity. Notably, high levels of unsaturated fatty acids in the rumen are associated with an increased risk of milk fat depression, potentially compromising overall dairy productivity.
Practices and technologies
Diet Reformulation Strategies: Lipid Supplementation
alternative practice name:
Fat Supplementation