Researchers tested different feed combinations for dairy cows to see if they could reduce methane gas (the burps cows release) while keeping milk production high. They fed 24 cows different diets over four months, mixing regular barley with high-oil oats, and comparing two types of protein supplements. They also tested a special additive called 3-NOP. The results showed that high-oil oats and certain protein supplements significantly reduced methane emissions by 11-33%, and high-oil oats even boosted milk production. However, the special additive reduced milk output slightly, suggesting farmers need to balance environmental benefits with production goals.

The Quick Take

  • What they studied: Whether changing what dairy cows eat could reduce the methane gas they produce (which contributes to climate change) while maintaining or improving milk production
  • Who participated: 24 healthy dairy cows (Nordic Red breed) that were actively producing milk, tested over a 4-month period with each cow receiving different feed combinations
  • Key finding: High-oil oats reduced methane emissions by 11-15% and increased milk production by 2.4 kg per day compared to regular barley. A special additive called 3-NOP cut methane by about one-third but slightly reduced milk output.
  • What it means for you: If you drink milk, this research suggests farmers may soon have practical ways to reduce environmental impact while maintaining milk supply. However, farmers will need to carefully choose which strategies work best for their operations, as some approaches that reduce methane may slightly decrease production.

The Research Details

Scientists conducted a carefully controlled experiment where they systematically changed what they fed 24 dairy cows over four separate 28-day periods. Each period included 18 days for the cows to adjust to new food and 10 days of careful measurement. The researchers tested eight different diet combinations by mixing and matching three variables: the grain source (regular barley versus high-oil oats), the protein supplement (standard rapeseed meal versus cold-pressed rapeseed cake), and whether or not to add a methane-reducing supplement called 3-NOP.

The base diet for all cows was the same—60% grass silage (a type of preserved grass)—with the remaining 40% being the experimental ingredients. The researchers measured everything carefully: how much the cows ate, how much milk they produced, their body weight, and the methane gas they released. They used a special system called GreenFeed to automatically measure gas emissions from each cow throughout the day.

This type of study design, called a factorial design, is powerful because it allows researchers to test multiple factors at once and see how they interact with each other. For example, they could see whether high-oil oats worked better with one protein supplement than another.

This research approach matters because it mimics real farming conditions while maintaining strict scientific control. Rather than testing one change at a time (which would take years), the researchers tested multiple practical feed combinations simultaneously. This helps farmers understand which real-world combinations actually work together to reduce methane while maintaining productivity. The careful measurement of methane using automated technology ensures accurate results rather than estimates.

This study has several strengths: it used a controlled experimental design with multiple repetitions, included careful measurements of methane using automated equipment, and tested practical feed ingredients that farmers could actually use. However, the study used only 24 cows of one breed in one location, so results might differ in other regions or with different cow breeds. The study lasted four months, which is a reasonable timeframe but doesn’t show long-term effects. The researchers carefully controlled all variables except the ones they were testing, which strengthens confidence in the results.

What the Results Show

High-oil oats produced impressive results when combined with standard rapeseed meal: they reduced daily methane emissions by 11.2%, methane per unit of feed eaten by 14.2%, and methane per unit of milk produced by 15.3%. Even more importantly, high-oil oats increased milk production by 2.4 kg per day compared to barley, meaning cows produced more milk while releasing less methane—a win-win scenario.

The special additive 3-NOP was the most powerful methane reducer, cutting emissions by about one-third (33.5% reduction in daily emissions, 30.9% reduction per unit of feed, and 31.2% reduction per unit of milk). This is a substantial improvement for climate impact. However, this additive came with a trade-off: milk production decreased by 1.1 kg per day, which would concern farmers focused on production.

Cold-pressed rapeseed cake (a protein supplement) also reduced methane by 12.5% in daily emissions when combined with barley, but this benefit disappeared when combined with high-oil oats. This shows that different feed ingredients interact in complex ways—what works well with one ingredient might not work with another.

The researchers also found that high-oil oats improved how efficiently cows converted feed into milk, meaning less wasted feed. However, milk protein concentration (the amount of protein in the milk) decreased slightly with high-oil oats, which might matter to some dairy processors.

The study revealed several additional findings worth noting. Cows eating high-oil oats tended to eat slightly more total feed, suggesting these oats are palatable (cows like eating them). The digestibility of some nutrients decreased with high-oil oats, meaning the cows’ bodies didn’t absorb all the nutrients as efficiently—yet they still produced more milk, indicating the high-oil oats provided other benefits. Urinary urea levels (a marker of protein metabolism) were higher with high-oil oats, suggesting changes in how cows processed protein. These secondary findings help explain the mechanisms behind the primary results but don’t change the practical recommendations.

This research builds on existing knowledge that high-fat feeds can reduce methane in ruminant animals. The finding that high-oil oats increase milk production while reducing methane is particularly valuable because previous research sometimes showed trade-offs between these goals. The 3-NOP results align with previous studies showing this additive effectively reduces methane, though the production decrease is consistent with prior observations. The interaction effects (where different ingredients work better or worse together) add new practical knowledge that wasn’t well-documented before.

The study used only 24 cows of a single breed (Nordic Red) in what appears to be a single location, so results might differ with other breeds or in different climates. The experiment lasted only four months, so we don’t know if these effects continue long-term or if cows adapt over time. The study didn’t measure economic costs, so farmers don’t know if the feed ingredients cost more than traditional options. The researchers didn’t test these diets on cows in different production stages (early lactation versus late lactation), so results might vary. Finally, the study was conducted in a controlled research setting, which may differ from typical farm conditions where cows might experience stress or illness.

The Bottom Line

Based on this research, high-oil oats appear to be a practical recommendation for dairy farmers wanting to reduce methane while improving milk production (moderate-to-high confidence). Cold-pressed rapeseed cake shows promise for methane reduction but with less consistent benefits (moderate confidence). The 3-NOP additive effectively reduces methane but requires accepting lower milk production, so it’s only recommended if environmental goals outweigh production concerns (high confidence in methane reduction, but with production trade-offs). Farmers should consider combining high-oil oats with standard rapeseed meal for the best balance of methane reduction and milk production.

Dairy farmers should care about these findings, especially those in regions with environmental regulations on methane emissions or those seeking to market environmentally-friendly milk. Consumers interested in reducing their environmental impact through food choices should care, as these strategies could make dairy production more sustainable. Environmental policymakers should care because practical solutions like these could help agriculture meet climate goals. However, farmers with very tight profit margins might not be able to afford these feed changes, and the recommendations may not apply to non-dairy cattle operations or different climates.

Farmers could expect to see changes in methane emissions within days to weeks of switching feeds, as methane production is directly related to what cows eat. Milk production changes would also appear within the first week or two. However, the full benefits might take 2-3 weeks as cows fully adapt to new diets. Long-term sustainability of these benefits beyond several months remains unknown based on this study.

Want to Apply This Research?

  • Track daily milk production (in kg) and estimated methane reduction percentage weekly. Users can input their current feed ingredients and compare projected methane reduction: high-oil oats alone = ~11-15% reduction, cold-pressed rapeseed cake = ~12% reduction, or 3-NOP additive = ~33% reduction.
  • Farmers using a dairy management app could set a goal to transition 25% of their barley feed to high-oil oats in week 1, 50% in week 2, and 75% in week 3, with full transition by week 4. The app could send reminders to monitor milk production during the transition and alert the farmer if production drops unexpectedly.
  • Establish a baseline of current milk production and estimated methane emissions, then track weekly milk yield, feed costs, and any changes in milk composition (protein percentage). Create a dashboard showing methane reduction progress versus production changes, allowing farmers to optimize their specific feed mix based on their priorities.

This research describes results from a controlled study with 24 dairy cows and may not apply to all farms, breeds, or climates. Farmers should consult with their veterinarian or agricultural extension specialist before making major changes to their cattle’s diet, as individual herd responses may vary. The study was conducted in a research setting and may not reflect real-world farm conditions. While the findings are promising, farmers should consider economic factors, local feed availability, and their specific production goals before implementing these dietary changes. This information is for educational purposes and should not replace professional agricultural advice.