Recommendations for identification and selection of bioactive compounds to develop antimethanogenic feed additives. Dr. Yáñez-Ruiz (8:23)

How can we search for molecules that modify how feed is fermented in the rumen? Conventionally, we have used scientific literature to look for plant extracts and compounds that have been researched before. Now, we have computational technology that offers opportunities to model how molecules interact with rumen microbes. Once a candidate compound is selected, in vitro tools can be used to test dose responses before animal experiments.

Recommendations for testing enteric methane-mitigating feed additives in ruminant studies.

Dr. Yáñez-Ruiz for Dr. Alexander Hristov (17:07)

Once compounds have been identified and selected, they need to be tested in the animal. These experiments are costly and best practices for experimental design, animals used, diets fed, delivery of the test compound, and measurement of methane should be followed. Some of these guidelines are strongly linked to the regulatory aspects that provide requirements for how in vivo trials need to be conducted.

Feed additives for methane mitigation: Modeling the impact of feed additives on enteric methane emission of ruminants—Approaches and recommendations. Dr. Bannink (22:43)

Once experimental data is collected, it can be used to develop models to predict how effective an additive is, how it works, and its relevance. The intention is to quantify how an additive will work if you feed it to an animal. This can be complex due to variation among different datasets and natural fluctuation in methane production in the animal. One factor that plays a big role in the effectiveness of additives is the type of diet that animals are fed.

A guideline to uncover the mode of action of antimethanogenic feed additives for ruminants. Dr. Belanche (30:03)

Understanding the mechanism of action for methane mitigants is challenging. We know some compounds work to reduce methane, but we don’t know how or why they are working. There are five main types of additives when grouped by mode of action: modify rumen fermentation to decrease hydrogen production; methane inhibitors that act specifically against methanogens; inhibit enzymes common to all methanogens; hydrogen sinks to redirect hydrogen away from methanogenesis and toward other metabolic pathways; and promote methanotrophs that oxidize methane. The most effective are methane inhibitors, which decrease methane but don’t increase animal productivity. Combining a methane inhibitor with a hydrogen sink may help redirect hydrogen and result in improved animal productivity.

Regulations and evidence requirements for the authorization of enteric methane-mitigating feed additives. Dr. Tricarico (41:22)

There are as many regulatory systems as there are jurisdictions. Two concepts that are shared across jurisdictions are regulatory status/legal classification and intended use. While each jurisdiction requires some legal classification of a feed additive compound, each has a different criteria base from which they classify products. For example, “inhibitor” is a legal classification in New Zealand, but doesn’t even exist in other jurisdictions. Sometimes, the same word may mean different things in different jurisdictions. Authorization of a compound is not a blanket authorization, it is an authorization of the intended use of the compound. This specificity is critical for all involved to understand.

Feed additives for methane mitigation: How to account for the mitigating potential of antimethanogenic feed additives—Approaches and recommendations. Dr. del Prado (49:42)

A major challenge in this area is what kind of accounting system will be used: farm level, lifecycle analysis, carbon markets, national greenhouse gas inventories, etc. An accounting system needs to be well tailored from the type of experimental data available to the complexity used on the scale of the method. Experimental data, modeling, and accounting move hand-in-hand.

Panelists share their take-home thoughts. (58:57)

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Feed Additives to Mitigate Methane with guests: Dr. David Yáñez - Ruiz, CSIC; Dr. André Bannink, Wageningen Universi ty & Research; Dr. Alejandro Belanche, University of Zaragoza; Dr. Juan Tricarico, Dairy Management Inc.; Dr. Agustin del Prado