MODERN TIMES: SOLUTIONS FOR REDUCING METHANE IN LIVESTOCK

Bruna Silper, Heloise Duarte e Luiz Gustavo Pereira
Jan 31
10 min read

Modern livestock farming faces the challenge of reducing emissions of enteric methane, a potent greenhouse gas, without compromising productivity. Learn practical and innovative strategies to achieve this balance.

Reducing methane (CH₄) emissions is one of the main challenges for livestock farming in terms of sustainability and global warming mitigation. As a greenhouse gas (GHG), methane has a warming potential 28 times greater than that of carbon dioxide (CO₂). However, while methane remains in the atmosphere for approximately 12 years before reintegrating into the carbon cycle and ceasing to contribute to global warming, carbon dioxide continues to contribute to the greenhouse effect for over 200 years. Enteric methane production by ruminants, which occurs during rumen fermentation, accounts for approximately 30% of global anthropogenic methane emissions—those resulting directly from human activities such as agriculture, livestock, industry, and transportation. Given this significant contribution, the livestock sector is under increasing pressure to adopt effective mitigation solutions.

As Lulu Santos aptly puts it in "Modern Times," "time flies," and the need to act in favor of sustainability becomes increasingly urgent. Livestock farming is entering a new era, marked by innovations in management practices, biotechnology, and genetics, which are essential to mitigating methane emissions. In this article, inspired by the comprehensive review by Beauchemin et al. (2022) published in the Journal of Dairy Science , we present mitigation strategies in detail, organized by category and aligned with farm emission profiles.

Strategies for mitigating methane

Based on the review, mitigation strategies can be grouped into three broad categories: 'Management and dietary changes and increased efficiency', 'Technological and biological interventions', and 'Genetic selection and long-term practices'. Table 1 summarizes the complementary factors and impacts of each strategy.

1. Changes in management and diet and increased efficiency

These strategies involve direct interventions in animal diet and management, aiming to dilute methane emissions per unit produced and/or reduce enteric methane emissions.

Increasing animal productivity : Dietary balance, pasture management, and animal health are essential to increasing production per animal or hectare. This increased efficiency dilutes methane emissions per unit of product.

Increased forage digestibility : High-quality forages, harvested at the correct stage and properly processed, contribute to more efficient digestion and increased nutrient absorption. High-quality silages, such as corn or sorghum, promote greater digestibility, reducing the need for prolonged rumen fermentation and thus reducing methane emissions per unit of product.

Perennial Legumes : Introducing perennial legumes, such as alfalfa and clover, improves diet quality and reduces the need for nitrogen fertilizers during crop cultivation. These plants not only provide high-quality protein but also promote digestibility, resulting in lower methane emissions.

High-sugar grasses : These grasses, like some ryegrass varieties, promote increased production of propionate, a fatty acid that, during its formation, captures available hydrogen in the rumen, resulting in reduced substrate availability for rumen methane production. This adjustment improves digestibility and helps reduce enteric methane emissions.

Concentrate Amount : Diets adjusted for a higher concentrate content relative to roughage increase the proportion of propionate to acetate. Less acetate can reduce methane production. The balance between concentrates and roughage should consider rumen health, feed efficiency, and costs.

Starch-rich forages: These forages, such as corn silage and wet grain silage, promote propionate production, similar to the mechanism presented for concentrate levels in the diet, resulting in lower enteric methane emissions. Furthermore, the high starch content of these forages increases feed efficiency and promotes better production performance.

Lipid supplementation : Adding lipids to the diet, such as vegetable oils (sunflower, canola, flaxseed) or protected fats, is an effective way to reduce methane emissions. Lipids interfere with fermentation and, by reducing the availability of hydrogen for methane synthesis, contribute to a reduction in emissions. Studies indicate reductions of up to 20% in methane production with adequate lipid supplementation. However, this result depends on the source and form of lipid supply.

Pasture Management : Strategic pasture management, such as rotational grazing and adjusting stocking rates, helps improve pasture nutritional quality. Consumption of well-managed pastures results in more digestible diets. Additionally, well-managed pastures sequester carbon in the soil, contributing to both emissions mitigation and CO₂ sequestration.

Most mitigation strategies are related to general and nutritional management

2. Technological and biological interventions

These strategies involve the use of additives and biological interventions to mitigate methane production directly in the rumen.

Methanogenesis inhibitors (3-NOP) : This substance directly inhibits methane production in the rumen by blocking the enzymes responsible for methane synthesis. Studies indicate that including it in dairy cattle diets can reduce methane emissions by up to 30%.

Ionophores : These are compounds, such as monensin, that increase the efficiency of ruminal fermentation, promoting a less favorable environment for methanogenic microorganisms. They reduce acetate formation but have a marginal impact on the mitigation of enteric methane in dairy cattle (approximately 3%), and their effects are transient. It is worth remembering that ionophores are antibiotics, and many countries have already banned their use as performance enhancers.

Probiotics : These are live microorganisms added to the diet to modulate the rumen microbiota, redirecting metabolic hydrogen into alternative pathways and competing with methanogenic microorganisms. Although in vitro studies show promising effects in reducing methane formation, in vivo efficacy presents challenges, such as the required dose and survival in the rumen. To maximize their effect, probiotics can be strategically combined with other additives, such as chemical inhibitors, to achieve synergistic effects in mitigating emissions.

Essential oils : These extracts have antimicrobial properties that interfere with bacterial function. Studies show reductions of up to 22% in CH₄ emissions in animals supplemented with commercial products based on essential oils, such as oregano oil. However, there are challenges related to dosage and stability.

Nitrate supplementation : Nitrates act as electron acceptors in the rumen, competing with methanogenic microorganisms for available hydrogen, diverting it from methane production. Nitrate use requires careful management to avoid nitrite toxicity, but it has proven effective in reducing enteric emissions, reducing enteric methane production by approximately 15%.

Use of macroalgae ( Asparagopsis spp.) : The introduction of macroalgae, such as Asparagopsis spp., into ruminant diets has proven highly effective in reducing enteric methane emissions, with studies indicating reductions of up to 80%. This effectiveness is attributed to the bioactive compounds present in algae, such as bromoform, which inhibit the action of methanogenic enzymes in the rumen. However, logistical and dietary acceptance challenges remain that need to be addressed to make its implementation feasible on a large scale.

3. Genetic selection and long-term practices

These strategies involve developing practices that, over time, can bring substantial reductions in methane emissions.

Selection of animals with low CH₄ production : The enteric methane emission trait has moderate heritability in cattle. Genetic improvement programs have identified animals with lower methane emissions, which may represent a long-term solution, but long-term studies are still needed to ensure there will be no adverse effects on animal health and performance characteristics. The introduction of genetically selected bulls, recently implemented in some countries, could result in herds with lower methane emissions without compromising productivity.

Forage Preservation and Processing : Advanced forage processing techniques, such as the production of high-quality silages, help optimize digestion and reduce prolonged rumen fermentation, reducing enteric methane production. Proper preservation also ensures a consistent supply of quality forage.

Tannins and saponins : These natural substances, found in specific plants, have antimicrobial properties that can inhibit the action of methanogenic microorganisms in the rumen. Tannins, found in legumes such as red clover, are effective in reducing methane production and contribute to better rumen health.

Table 1. Methane mitigation strategies with additional information on the items evaluated

* Safety for the environment and humans

** Safety for animals, consumers and the environment

Choosing mitigation strategies: basic principles for assertive choices

After presenting the main mitigation strategies, it is crucial to understand how they can be applied in a personalized manner to each farm's profile. Farms with a low carbon footprint in milk should adopt different strategies than those with a higher footprint. Dairy farms can be classified as having a low, medium, or high carbon footprint (CO₂ equivalent per kg of milk). Figure 1.

Figure 1. Classification by profile of the carbon footprint of milk

FPCM: kg of milk corrected to 4.0% fat and 3.3% protein

This categorization allows for a targeted and more effective approach to applying mitigation strategies:

- High carbon footprint farms (≥ 2.0 kg CO₂ eq/kg milk) They face structural challenges, such as a high percentage of dry cows in the herd, high morbidity and mortality rates, and low production efficiency. Therefore, strategies should focus on optimizing herd management and nutritional improvements. It is essential to adopt practices that increase the proportion of lactating cows and reduce morbidity and mortality rates through appropriate reproductive management and rigorous disease control. Nutritional improvements, balancing concentrates and high-quality forages, increase digestive efficiency and reduce rumen fermentation time. Additionally, investments in genetic improvement programs can contribute to the selection of more productive and healthy animals. Forage quality is also a crucial factor; pasture management practices, such as rotational grazing, which ensure the intake of more digestible forage, help improve animal performance and reduce the animal's footprint.

- Farms with a medium carbon footprint (1.0 to 2.0 kg CO₂ eq/kg of milk) generally need to balance nutritional adjustments with efficiency improvements. Strategies such as increasing concentrate and lipid content in the diet can contribute to reducing methane emissions, but require a careful cost-benefit analysis to ensure economic viability. Improving forage digestibility is essential to optimize animal performance and reduce emissions per unit of milk produced. Furthermore, investing in genetic improvement is crucial, prioritizing the selection of animals with traits that favor longevity and production efficiency.

Low-carbon footprint farms (≤1.0 kg CO₂ eq/kg milk) are recognized for their efficiency in producing milk with a carbon footprint close to the minimum emissions threshold. To achieve further reductions, these farms need to focus on specific optimization strategies. Including vegetable oils and lipids in the diet can help reduce methane emissions by up to 15%. The introduction of perennial legumes can be recommended to improve dietary protein content and reduce the need for nitrogen fertilizers in crops. Additionally, the use of additives such as 3-nitrooxypropanol (3-NOP) and nitrates can reduce methane production, even in already highly efficient systems.

Table 2. Analysis of strategies based on farm emissions profiles with some additional mitigation options

Challenges and opportunities

Despite the wide range of strategies to reduce milk's carbon footprint, large-scale adoption of these strategies still faces challenges, including the cost of technologies and the need for public policies to encourage investment in this area. Furthermore, it is crucial that the adoption of mitigation solutions be accompanied by technical support mechanisms for producers and involve consumer acceptance , as the demand for sustainable products has driven the sector to adopt low-carbon practices. The involvement of all links in the chain, from producers to distributors and end consumers, is crucial for the successful adoption of these practices. Overcoming the challenges of implementing enteric methane mitigation strategies requires a multifaceted approach, involving technical, economic, and institutional efforts.

Opportunities for Brazil

Brazil has great potential to excel in low-carbon milk and meat production, due to its rich biodiversity, favorable climate conditions, and ample availability of natural resources. Genetic improvement programs and advances in intensive production systems have shown significant reductions in methane emissions per unit of product. In recent years, Brazilian initiatives focused on the genetics of dairy breeds, such as the Girolando, have already resulted in a 25% to 38% reduction in carbon emissions intensity. Specific regions of the country, where models similar to those adopted in the US and EU are common, have achieved productivity levels similar to those observed in these countries.

Furthermore, pasture management practices represent an opportunity for Brazil. The integration of silvopastoral systems and rotational grazing, along with the use of high-quality grasses, has the potential to improve productivity while also contributing to increasing the carbon sequestration capacity of pastures, transforming them into important carbon sinks.

This combination of natural conditions, genetic innovation, and sustainable management practices positions Brazil as a potential leader in the transition to low-carbon livestock farming, offering competitive advantages in the global market.

A possible path

Enteric methane mitigation is more than an environmental responsibility; it is an economic and social necessity that will define the future of global livestock farming. The 17 strategies discussed in this article, based on the review by Beauchemin et al. (2022), present a wide range of approaches to reducing methane emissions, which can also increase productivity and improve the sustainability of the sector. Some of these solutions, such as production intensification and balanced diets, are already widely adopted, while others, such as the use of additives, are still in the development phase but have great potential to transform livestock farming.

Implementing these strategies requires coordinated efforts from all stakeholders in the livestock value chain. With adequate support from public policies, financial incentives, technological advances, and producer awareness, livestock farming can move toward a sustainable, low-carbon future. As highlighted by Beauchemin et al. (2022), achieving global methane emission reduction targets requires a combination of effective strategies, technical support, and engagement across the entire value chain. Figure 2 illustrates the steps involved in this process.

Figure 2. Sustainable Livestock Route

The success of mitigating enteric emissions will depend on producers' ability to adopt solutions adapted to their regional realities and production systems. Tools like PEC Calc, mentioned in previous columns, play a key role in allowing producers to estimate their emissions and compare their results with global benchmarks, promoting low-carbon and sustainable livestock farming.

As we move toward more sustainable livestock farming, the integration of these solutions, along with the continuous development of new technologies and management practices, will be crucial to balancing food production with environmental protection and social and economic development. Although the path to low-carbon livestock farming is challenging, Brazil can leverage existing technologies for sustainable production in the tropics and, in a balanced, integrated, and biodiverse manner, become a benchmark in the dairy sector. Adapting solutions to local realities and ensuring ongoing support will be key factors for success.

THE SUCCESS OF MITIGATING ENTERIC EMISSIONS WILL DEPEND ON THE ABILITY OF PRODUCERS TO ADOPT SOLUTIONS ADAPTED TO THEIR REGIONAL REALITIES AND PRODUCTION SYSTEMS

References

Karen A. Beauchemin, Emilio M. Ungerfeld, Adibe L. Abdalla, Clementina Alvarez,

Claudia Arndt, Philippe Becquet, Chaouki Benchaar, Alexandre Berndt, Rogerio M. Mauricio,

Tim A. McAllister, Walter Oyhantçabal, Saheed A. Salami, Laurence Shalloo, Yan Sun,

Juan Tricarico, Aimable Uwizeye, Camillo De Camillis, Martial Bernoux, Timothy Robinson,

and Ermias Kebreab (2022). Invited review: Current enteric methane mitigation options. Journal of Dairy Science , 105:9297–9326. https://doi.org/10.3168/jds.2022-22091