Replacing traditional pasture hay with Napier grass increased milk production by 41% in dairy cows while reducing methane emissions by 23% per liter of milk, according to a 2026 research study reviewed by Gram Research. Cows fed 100% Napier grass produced 16.1 liters of milk daily compared to 11.4 liters on traditional hay, with higher milk protein content and better feed efficiency. This suggests Napier grass could help small dairy farms produce more milk while reducing environmental impact, though the study involved only five cows in Ethiopia.
A Gram Research analysis of a dairy farming study found that replacing traditional pasture hay with Napier grass significantly improved milk production and reduced harmful methane emissions from cows. Researchers tested five different combinations of the two hay types on dairy cows in Ethiopia and discovered that cows eating 100% Napier grass produced 41% more milk daily (16.1 liters versus 11.4 liters) while producing 23% less methane per liter of milk. This finding suggests that switching to Napier grass could help small dairy farms produce more milk while being better for the environment—a win-win for farmers and the planet.
Key Statistics
A 2026 research study found that dairy cows fed 100% Napier grass hay produced 41% more milk per day (16.1 liters versus 11.4 liters) compared to cows fed only traditional pasture hay.
According to research reviewed by Gram Research, replacing pasture hay with Napier grass reduced estimated methane emissions by 23%, dropping from 26.9 grams to 20.6 grams per kilogram of milk produced.
A 2026 study of five dairy cows showed that Napier grass hay improved feed efficiency and increased milk protein yield compared to traditional pasture hay diets.
Research demonstrated that milk yield increased significantly from 11.4 to 16.1 liters per day when natural pasture hay was completely replaced with Napier grass hay in dairy cow diets.
The Quick Take
- What they studied: Whether feeding dairy cows Napier grass instead of regular pasture hay would change how much milk they produce, how healthy the milk is, and how much methane gas the cows release into the air.
- Who participated: Five crossbred dairy cows (a mix of different cattle breeds) in Ethiopia that were already producing milk. Each cow was tested on five different diet combinations over time.
- Key finding: Cows fed 100% Napier grass produced 41% more milk per day (16.1 liters instead of 11.4 liters) and released 23% less methane per liter of milk compared to cows fed only traditional pasture hay.
- What it means for you: If you’re a small dairy farmer, switching to Napier grass could help you produce more milk from the same number of cows while reducing your farm’s environmental impact. However, this study was small and conducted in Ethiopia, so results may vary in different climates or with different farming practices.
The Research Details
Researchers conducted an experiment using five dairy cows that were each tested on five different hay combinations. This is called a Latin square design, which means each cow tried each diet type in a rotating pattern. This approach helps scientists compare results fairly because each cow serves as its own comparison group.
The five diet combinations ranged from 100% traditional pasture hay to 100% Napier grass hay, with three mixed options in between (75/25, 50/50, and 25/75 combinations). All cows also received the same grain supplement based on how much milk they produced—about half a kilogram of grain per liter of milk.
Researchers measured how much the cows ate, how much milk they produced, the quality of the milk, and estimated how much methane gas each cow released. They used mathematical formulas to estimate methane production rather than directly measuring it.
Using each cow as its own comparison (rather than comparing different groups of cows) makes the results more reliable because it removes differences between individual animals. The Latin square design is considered a strong research method for small studies. However, the small number of cows (just five) means the results should be confirmed with larger studies before making major farming changes.
Strengths: The study used a scientifically sound design that controls for individual cow differences, and it measured multiple important outcomes (milk production, milk quality, feed efficiency, and emissions). The results were statistically significant, meaning they’re unlikely to be due to chance. Limitations: Only five cows were tested, which is a very small number. The study was conducted in one location (Ethiopia) with one type of crossbred cow, so results may not apply everywhere. Methane was estimated using formulas rather than directly measured, which is less precise than direct measurement.
What the Results Show
The most striking finding was the dramatic increase in milk production. Cows fed 100% Napier grass produced 16.1 liters of milk per day, compared to just 11.4 liters for cows fed only traditional pasture hay—a 41% increase. This improvement happened gradually as researchers increased the amount of Napier grass in the diet, suggesting the effect is dose-dependent.
Milk quality also improved. The milk from cows eating Napier grass contained more protein, which is important for cheese-making and nutrition. Feed efficiency—how much milk a cow produces per unit of feed eaten—also improved significantly, meaning cows got more productive from the same amount of food.
Perhaps most importantly for environmental concerns, estimated methane emissions dropped substantially. Cows on 100% Napier grass produced only 20.6 grams of methane per kilogram of milk, compared to 26.9 grams for cows on traditional hay—a 23% reduction. This means the cows were not only producing more milk but doing so while releasing less climate-damaging gas.
Cows eating more Napier grass consumed more total dry matter (the solid part of feed after removing water) and more crude protein. This higher protein intake likely explains both the increased milk production and the improved milk protein content. The concentrate (grain) supplementation remained constant at 0.5 kg per liter of milk, so the improvements came primarily from the hay change rather than from feeding more grain.
This study aligns with previous research showing that Napier grass is a high-quality forage crop for dairy cattle. Earlier studies have documented that Napier grass contains more protein and digestible nutrients than many traditional pasture grasses. However, most previous research was conducted in tropical regions with different cattle breeds and farming systems. This study is notable for specifically testing the methane reduction benefit in a smallholder farming context, which is important for developing countries where dairy farming is expanding rapidly.
The study used only five cows, which is a very small sample size. Results from such a small group may not apply to all dairy farms or all types of cattle. The study was conducted in Ethiopia with specific crossbred cows, so the results may differ in other countries or with different cattle breeds. Methane emissions were estimated using mathematical formulas rather than directly measured from the cows, which is less accurate. The study didn’t examine long-term effects or whether cows would maintain these improvements over months or years. Additionally, the study didn’t assess the cost of growing and harvesting Napier grass compared to traditional hay, which is crucial for farmers deciding whether to make the switch.
The Bottom Line
For small dairy farmers in tropical and subtropical climates: Consider transitioning to Napier grass hay as a primary feed source. The evidence is moderately strong (based on a controlled study, though with a small sample size) that this change could increase milk production by 30-40% while reducing environmental impact. Start by mixing Napier grass with your current hay rather than switching completely, to allow cows to adjust. Before making a full transition, evaluate whether you can grow or affordably source Napier grass in your area. For farmers in temperate climates: This research is less directly applicable, as Napier grass grows best in warm regions. Consult with local agricultural experts about similar high-protein grass alternatives suited to your climate.
Small dairy farmers in Ethiopia, East Africa, and other tropical regions should pay close attention to this research. Farmers looking to increase milk production without buying more cows or expensive grain supplements would benefit most. Environmental advocates and policymakers focused on reducing agricultural greenhouse gas emissions should also note these findings. Dairy cooperative leaders and agricultural extension workers can use this research to guide farmer training programs. Farmers in temperate climates should wait for similar studies with locally-adapted forage crops before making major changes.
Based on this study, improvements in milk production appeared within the timeframe of the experiment (which lasted several weeks per diet combination). However, this research doesn’t tell us whether benefits would continue long-term or whether cows would maintain higher production over months and years. Farmers should expect to see changes within 2-4 weeks of dietary transition, but should monitor their herds for at least 2-3 months to confirm sustained improvements. Environmental benefits (reduced methane per liter of milk) should appear immediately if the diet change is complete.
Frequently Asked Questions
Does Napier grass really make cows produce more milk?
Yes, according to a 2026 study, cows fed 100% Napier grass produced 41% more milk (16.1 liters daily) compared to those on traditional hay (11.4 liters). The milk also contained more protein. However, this study involved only five cows in Ethiopia, so results may vary elsewhere.
How much does Napier grass reduce cow methane emissions?
Research shows Napier grass reduced estimated methane emissions by 23% per liter of milk produced. Cows on Napier grass released 20.6 grams of methane per kilogram of milk versus 26.9 grams on traditional hay, making it more environmentally friendly.
Can I switch my dairy cows to Napier grass immediately?
Gradual transition is recommended. Start by replacing 25% of current hay with Napier grass, monitor for 2 weeks, then gradually increase the percentage over 4-6 weeks. This allows cows to adjust to the new feed and helps you confirm benefits apply to your specific herd.
Will Napier grass work for dairy farms outside tropical regions?
This study was conducted in Ethiopia with tropical conditions. Napier grass grows best in warm climates, so it may not be suitable for temperate regions. Farmers in cooler areas should consult local agricultural experts about high-protein grass alternatives adapted to their climate.
Is this study reliable enough to change my farming practices?
The study used a scientifically sound design but tested only five cows, which is a small sample size. Results are promising and worth trying on a small scale, but confirm benefits with your own herd before making complete changes. Larger studies would strengthen confidence in these findings.
Want to Apply This Research?
- Track daily milk production (liters per cow) and milk protein percentage weekly. Compare these metrics before and after introducing Napier grass, recording the percentage of Napier grass in each cow’s diet. This creates a personal data baseline to confirm whether the research findings apply to your specific herd.
- If you’re a dairy farmer, start by replacing 25% of your current hay with Napier grass while monitoring milk production and cow health for two weeks. If results are positive, gradually increase to 50%, then 75%, then 100% replacement over 4-6 weeks. Document feed costs, milk yield, and any changes in cow behavior or health at each stage.
- Establish a simple tracking system: record daily milk volume per cow, weekly milk protein content (if you have access to testing), weekly feed costs, and monthly average production. Compare these metrics to your baseline before the diet change. If milk production increases by 20% or more within 4 weeks and costs don’t increase proportionally, the change is working for your farm. Continue monitoring for at least 3 months to ensure the improvement is sustained.
This research summary is for informational purposes only and should not replace professional agricultural or veterinary advice. The study involved only five cows in Ethiopia and may not apply to all dairy farms, cattle breeds, or climates. Before making significant changes to your dairy herd’s diet, consult with a veterinarian, animal nutritionist, or agricultural extension specialist familiar with your local conditions. Individual results may vary based on cattle breed, climate, feed quality, and farm management practices. This summary does not constitute medical or professional agricultural advice.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.