Cutting methane emissions in livestock: Advances in feed additives

Amid global efforts to reduce our carbon footprint, creative thinking and research have joined forces to find ways to try to meet those goals. In the livestock industries, especially for beef and dairy cattle, research is being conducted into feed additives and using monitoring systems to reduce and track emissions.

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The benefits of reducing methane can extend past the environmental side and to the producers through economic benefits by boosting feed and production efficiency. For ruminants, rumen microbes are the key to methane production.

Microbes ferment feedstuffs and produce byproducts, including methane, a significant greenhouse gas. Grasses and hays, which take longer to digest, result in more methane production compared to concentrates like corn or non-human edible byproducts. Feed quality significantly impacts methane levels, and using high-quality ingredients is a straightforward strategy to reduce methane emissions.

Over the past few decades, beef and dairy cattle sectors have made substantial improvements in their carbon footprints as a result of the increase in knowledge about the nutritional quality of different feeds and their effects on methane formation, as explained by Angelica Carrazco, Ph.D. at the University of California-Davis CLEAR Center in her article “How can cattle feed additives reduce greenhouse gas emissions?”

Figure 1 – Feed additives that can reduce methane emissions.

Using feed additives

The cattle industries have invested heavily in feed additives to reduce methane emissions. This is a logical path since we’ve historically and scientifically seen how different feeds can impact production and animal health.

It can also be an economical plus, especially if additives are found locally and can be easily sourced and potentially replace more expensive ingredients or unavailable ingredients (Figure 1).

The effects and results will vary based on the additive. Though a few (like Agolin Ruminant) are commercially available, many are still in the research stages.

“Methane inhibitors block, or inhibit, the formation of methane by a change in the structure or the function of key drivers of methane formation,” writes Carrazco. “Commonly known additives that fall under this umbrella include 3-nitrooxypropanol (3NOP) and the bromoform occurring/existing naturally in the red seaweed Asparagopsis taxiformis.”

Rumen fermentation modifiers lead to additional favourable changes in the environment of the rumen. It decreases methane formation, in addition to improving animal productivity and health through increased availability of dietary protein.

Rumen modifiers help to “protect” the protein against loss to the microbes in the rumen. This in return increases the availability of the protein. Rumen modifiers include ionophores, which are man-made and tannins and essential oils that are naturally occurring.

Essential oils are also secondary plant metabolites and vary widely in structure and function. Photo: Katrien van t’Hooft

A standout feed additive being researched is 3NOP. According to Carrazco, it was designed specifically to inhibit methane formation. It has been able to decrease methane yield up to 36% in dairy cattle and 50% in beef cattle. One of the greatest challenges with 3NOP will be the acceptance by producers and the consumer.

Tannins are a class of secondary metabolites of plants and are known for their ability to bind to and denature proteins. This binding of proteins leads to reduced protein breakdown in the rumen and more breakdown in the abomasum. Certain tannins have demonstrated the potential for reducing enteric methane emissions by 13-16% in dairy cattle. A potential con to tannins is that overfeeding can cause an undesired result where cattle have a more difficult time digesting their feed.

Excess hydrogen in the rumen can inhibit fermentation processes. Nitrates, which are naturally present in soil, plants, and water, can help reduce hydrogen levels because they have a higher affinity for hydrogen. By converting nitrates to nitrites and then to ammonia, the rumen microbes effectively lower hydrogen concentrations, thereby supporting more efficient fermentation.

“Nitrate supplementation has been found to reduce methane emissions by up to 16% in dairy and 12% in beef cattle. The downside to this is that nitrate can be converted to nitrite, which can be toxic to ruminants if the levels are too high or exposure is prolonged. The amount of nitrate in the diet would therefore need to be closely monitored in order to prevent the risk of toxicity,” says Carrazco.

Essential oils are also secondary plant metabolites and vary widely in structure and function. They are commonly known for their antioxidant and immunological properties. In addition to their demonstrated ability to reduce methane emissions, there have been minor animal health and performance benefits. Two essential oil blends are of interest: Agolin (a blend of coriander seed oil, nutmeg extract and wild carrot) and Mootral (a blend of garlic and citrus extracts).

Beyond emission reduction

While the primary focus of many nutrition-related monitoring systems is to reduce emissions, they may also provide other valuable insights about animal well-being such as activity showing signs of stress or illness, rumination indicating health issues and temperature which can spot infections and metabolic diseases.
These systems offer a more comprehensive understanding of animal health and allow for timely interventions to address any issues that may arise.

Figure 2 – Process of methane production in ruminants.

Data-driven decision making

The data collected from these monitoring systems can be used to make informed decisions about animal nutrition and management. For example, if rumination patterns decline, it may be necessary to adjust the feed formulation or investigate potential health problems. By leveraging this data, farmers can optimise animal health, improve feed efficiency and ultimately enhance overall productivity (Figure 2).
While there are benefits to the producer who wants to reduce methane released by ruminants, the challenge is finding the right one that works and makes sense across the board. It has to not only be economical but also maintain the animal for health and production. When we meet these beginning criteria we are on the right track.
It does not make sense to make sacrifices on the producer side just to reduce a few emissions. But if we can reduce emissions and be successful on the producer side, there are huge societal benefits.
Feed additives continue to be explored as part of a comprehensive effort to reduce carbon footprint, with the objective of a more sustainable food system.