News
July 29, 2026
Bovaer® is a feed supplement that reduces enteric methane emissions by on average 30% in dairy cows and 45% in beef cattle, backed by more than 15 years of scientific research. It is the most extensively studied solution to enteric methane from livestock, with more than 140 peer-reviewed publications documenting its performance across diets, breeds, and production systems. This article synthesizes the most significant findings from 2022 to 2025, spanning dairy cows, beef cattle, and small ruminants across more than 25 countries. The findings address how dose and diet composition shape the size of the reduction, whether the effect holds over a full lactation, and how Bovaer® performs in partial grazing systems.
| Theme | Key findings |
| Predictable efficacy driven by dose and diet | Steps towards having an even sharper predictive model for Bovaer®. Bovaer® reduces enteric methane emissions by on average 30% in dairy cows and 45% in feedlot beef cattle. Dose level and diet composition are the two main drivers: higher doses and diets richer in starch with lower NDF deliver larger reductions (Kebreab et al., 2022; Van Gastelen et al., 2022). |
| Long-term consistent effect on methane reduction | The methane-reducing effect holds over a full lactation with no decline over time. Bovaer® is effective in extended use (12+ month study) with no adaptation effect from the rumen. Two full lactation studies proved the consistent and persistent effect of Bovaer®, expanding long-term study results to now also include data from Fleckvieh and Brown Swiss dairy cows (Van Gastelen et al., 2024; LfL Bavaria, 2025). |
| Effective in partial grazing system | A partial grazing dairy study (6 hours/day) confirmed methane reductions remain consistently at the same level in mixed barn and pasture systems, without affecting dry matter intake or milk yield within either system (Van de Gucht et al., 2025). |
Bovaer® reduces enteric methane emissions by on average 30% in dairy cows and 45% in feedlot beef cattle. Dose level and diet composition determine how large that reduction is in any given situation.
A meta-analysis of 13 published experiments established this relationship quantitatively: higher doses produce larger reductions, and diets with higher starch and lower neutral detergent fiber (NDF) content deliver greater methane reduction potential. That relationship is now recognised and adopted by carbon footprinting tools including the Cool Farm Tool, the Kringloopwijzer, and Sustell, making it a credible input for scope 3 emissions accounting across dairy supply chains.
*ppm = mg/kg DM. Methane reduction in CO2e amounted to 1.2-1.7 mT per year for NL. Source: van Gastelen et al 2022, Jnl Dairy Sci
A study comparing grass silage and corn silage-based diets in Holstein-Friesian dairy cows confirmed that diet composition shapes the size of the reduction, with corn silage diets delivering a numerically greater effect. More recent work at Aarhus University extended this to grass-clover silage systems. While forage quality affected how much methane cows produced overall, Bovaer®'s methane-reducing effect remained consistent across silage types, achieving an average methane yield reduction of 28.1% regardless of nutritional quality. Forage quality is therefore a relevant variable for predicting baseline emissions, but does not alter Bovaer®'s effectiveness.
That body of work now feeds into a predictive model under development at Wageningen University and Research, designed to further improve the accuracy of the expected reduction for a specific diet composition, rather than relying on an average across all conditions.
The short answer is no. Two independent year-long studies reach the same conclusion: Bovaer®'s methane-reducing effect is sustained, with no sign of rumen adaptation over time.
A year-long on-farm study in Holstein-Friesian dairy cows at Wageningen University and Research found a consistent reduction in methane yield over the course of the study, which covered all stages of lactation, including the dry period. The degree of reduction differed depending on diet composition, as diets were adjusted to meet the different energy requirements at each stage of lactation. Beyond methane reduction, the study also showed positive results on zootechnical parameters: dry matter intake was unaffected, milk yield was numerically increased (+1.3 kg/d), and energy-corrected milk yield was significantly higher in the Bovaer® group (+2.3 kg/d), driving a 6.3% increase in feed efficiency.
A subsequent study at LfL Bavaria, covering Fleckvieh and Brown Swiss dairy cows over 51 weeks, further confirmed the persistency and consistency of effect: a minimum 26% reduction in methane yield across all of lactation, with stable feed intake and milk production. The rumen does not adapt to Bovaer® supplementation, and the methane reduction persists over time.
Methane emissions (g/cow/day), dry matter intake and energy-corrected milk (ECM, kg/day) in Bovaer® and control groups over a full lactation period (51 weeks). Source: LfL Bavarian State Research Center for Agriculture, Germany (2023–2025).
In a published study, ILVO and Ghent University evaluated the efficacy of Bovaer® in dairy cows under both partial grazing and fully housed conditions. The partial grazing study involved cows that spent six hours per day at pasture and the remaining 18 hours in the barn, while the second study involved cows housed indoors full-time. In each study, cows receiving Bovaer® were compared with a control group.
The methane reduction (g/head/d) was the same in both Bovaer® supplemented groups regardless of time spent grazing, at between 25% and 27%, consistent with what has been established for Bovaer® in housed systems. Bovaer® did not affect dry matter intake, milk yield, or energy-corrected milk performance within either system. These results confirm that meaningful methane reductions are achievable in partial grazing systems, not just in housed, TMR-fed settings.
Methane emissions (g/head/day), dry matter intake and energy-corrected milk (ECM, kg/head/day) in dairy cows under barn feeding and mixed grazing systems with and without Bovaer® supplementation. Source: ILVO Vlaanderen study, Belgium, 2024.
The studies above are expanding confirmed efficacy of Bovaer® across farming conditions. At the same time, recent independent research from ETH Zurich, CSIC, SRUC, Ghent University, and ILVO has broadened understanding of the interaction between dietary composition, feed supplements, and methane emissions. These studies provide important insights into optimizing methane mitigation across a range of production systems and feeding strategies. Together these sets of results reinforce confidence in the role Bovaer® can play as part of a science-based approach to improving the environmental sustainability of livestock production.
