Philadelphia, March 7, 2025 – After many decades of research, the dairy sector has a significant body of peer-reviewed research showing that feed additives can effectively reduce methane, the greenhouse gas that makes up most of dairy's environmental footprint. Yet the practical use of this knowledge on farms—as well as general awareness around additive effectiveness and safety—is still gaining momentum. At this critical point in the dairy sector's pathway to a net-zero future, the Journal of Dairy Science , the leading general dairy research journal from the American Dairy Science Association (ADSA), published by Elsevier, has released a special issue translating this nutrition innovation into detailed technical recommendations on developing and implementing feed additives. The result is a feed additive toolkit to help researchers, dairy professionals, product developers, producers, and consumers fill knowledge gaps and supercharge feed additive adoption to reduce dairy's environmental footprint today and into the future.
This issue, Feed Additives for Methane Mitigation , presents the first outcomes of a flagship project by the Feed and Nutrition Network of the Global Research Alliance on Agricultural Greenhouse Gases ' Livestock Research Group. David Yáñez-Ruiz, PhD, of the Spanish Research Council (CSIC; Granada, Spain), one of the project's co-leads, explained, "This collaborative effort gathered 60 leading researchers from 46 institutions across 23 countries to form a robust network of scientists dedicated to reducing methane emissions from ruminants, which is a crucial goal as we combat climate change."
André Bannink, PhD, of Wageningen University & Research (Wageningen, the Netherlands), the second co-lead of this initiative, added, "Our goal is to provide the scientific community and livestock sector with technical guidelines on best practices for developing and testing feed additives, which we know is currently our most powerful methane-reduction tool."
The issue's introduction provides an overview of all six articles and explains the overall goals of the project team. Journal of Dairy Science Guest Editor Michael Kreuzer, PhD, professor emeritus at ETH Zurich (Lindau, Switzerland), explained, "Because of huge scientific leaps forward, we, as a society, now have the technical knowledge available to help each country, region, and farm find a path to methane reduction tailored to their unique need. It's time then to turn the attention of scientists, extensionists, industry, and farmers to the actual application of this knowledge on a broader scale."
The first step in developing feed additives is to find and test the actual bioactive compounds that inhibit methane produced by microorganisms in the digestive tract of animals. The guidelines open with recommendations for this process, including two different approaches for selecting the compounds—empirical (screening compounds already identified in databases) or mechanistic (discovering new and unidentified compounds based on our knowledge of animal biology). Once selected, the authors outline the initial lab tests needed to understand the compounds' impact on methane, considering factors such as dosage, formulation, and how they might interact with an animal's diet and the complex microbial fermentation in the rumen.
Once tested in a lab, the next step is to trial feed additives with animals to understand their efficacy and safety. The second article in the special issue provides guidelines for designing and conducting these studies to meet the most rigorous standards, including techniques for measuring enteric methane emissions. The guidelines also cover analyzing the resulting data to determine the feed additives' efficacy in achieving methane reduction and, critically, the safety of these additives for the animals consuming them and the nutritional composition of the final milk and meat products.
As these feed additives are introduced under various farming conditions, future modeling will become increasingly important to understand their effects at different scales and in varying environments. The third article in the special issue includes recommendations and guidelines for modeling the effects of feed additives, including the type of models used, the modeling objectives, and data availability while accounting for synergies and trade-offs. The authors' recommendations present modeling approaches for understanding an additive's impact on methane emissions at the farm and national, regional, and global levels.
Dr, Kreuzer commented, "As we work toward a shared and comprehensive understanding of methane-mitigating feed additives, one key gap we need to fill is exactly how these compounds work—or their mode of action."
The issue's fourth article explores the best approaches for elucidating the microbiological and biochemical changes that occur when additives are incorporated into a ruminant's diet. The authors explain that uncovering the mode of action can be a difficult and costly task involving specialized equipment, facilities, and resources. This stage of testing involves identifying which microbes are targeted by the additive to understand the mechanisms happening at the cellular and molecular levels and to map the pathways where the active compounds can be degraded in the animals' digestive tract. Understanding the specific mode of action of each compound is critical for providing appropriate use recommendations for different livestock production systems. They recommend conducting this research only after lab and animal studies have shown an additive's effectiveness and safety.
All this testing and modeling lead to the ultimate goal of getting methane-reducing feed additives authorized and approved for official commercial use, which is the topic of the next article in the special issue. Although exact requirements differ from country to country, all additive regulations are enforced to ensure the health and safety of the animals consuming them, the workers manufacturing and handling them, and the consumers enjoying the finished dairy products. The approval process also requires proof that additives are effective for their specific purpose and puts consumer-production guardrails around misleading marketing claims. The authors synthesize the legislation and legal procedures in Australia, Canada, the European Union, New Zealand, South Korea, the United Kingdom, and the United States as examples, offering actionable recommendations for both scientists and applicants seeking official feed additive authorization.
Once approved and deployed commercially, the question, "What kind of emissions impact can we anticipate from these additives in our complex global farming systems?" looms. The special issue concludes with a final article with recommendations for quantifying methane reduction—from individual animal measurements to national-level inventories. It emphasizes the importance of considering factors like the specific additive used, its delivery method, and potential impacts on other parts of the livestock production system. The result is a framework for accurately assessing the potential environmental benefits of feed additives, which is crucial for promoting their widespread adoption and supporting effective emission-mitigation strategies across the livestock sector.
Together, these six articles detail robust technical recommendations from additive development to impact measurement and provide actionable best practices and a roadmap with the potential to contribute significantly to global livestock climate efforts.
Explaining the significance of the special issue, the journal's editor in chief, Paul Kononoff, PhD, added, "These guidelines represent an enormous, interconnected global effort to ensure that tomorrow's dairy and livestock sectors can both continue to provide essential nutrition and contribute to a more sustainable future."
Explore the insights from the special issue via a recorded webinar with the authors, and join them for an in-depth, half-day symposium at the 2025 ADSA Annual Meeting taking place June 22-25 in Louisville, Kentucky.
