Abstract
Enteric methane emissions are the single largest source of direct greenhouse gas emissions (GHG) in beef and dairy value chains and a substantial contributor to anthropogenic methane emissions globally. In late 2019, the World Wildlife Fund (WWF), the Advanced Research Projects Agency-Energy (ARPA-E) and the Foundation for Food and Agriculture Research (FFAR) convened approximately 50 stakeholders representing research and production of seaweeds, animal feeds, dairy cattle, and beef and dairy foods to discuss challenges and opportunities associated with the use of seaweed-based ingredients to reduce enteric methane emissions. This Perspective article describes the considerations identified by the workshop participants and suggests next steps for the further development and evaluation of seaweed-based feed ingredients as enteric methane mitigants. Although numerous compounds derived from sources other than seaweed have been identified as having enteric methane mitigation potential, these mitigants are outside the scope of this article.
Generated Summary
This perspective article discusses the key considerations for utilizing seaweed-based ingredients to reduce enteric methane emissions from cattle. The study involved workshop participants from various sectors, including seaweed and feed production, dairy and beef cattle farming, and research. The primary focus of the research is the use of seaweed as a feed ingredient for ruminants to mitigate methane production, a significant contributor to greenhouse gas emissions. The article emphasizes that the current use of seaweed in livestock diets is not widespread due to the need for regulatory approval and the absence of legislative mandates. Furthermore, the study highlights the potential of various seaweed species to reduce methane production in cattle, specifically noting the effectiveness of Asparagopsis taxiformis. The study includes an overview of existing research, potential benefits, and challenges associated with the adoption of seaweed-based feed additives in the livestock industry.
Key Findings & Statistics
- Enteric methane emissions are the single largest source of direct greenhouse gas emissions (GHG) in beef and dairy value chains.
- In the U.S., an estimated 26.7% of total CH4 emissions are attributed to enteric fermentation, which corresponds to approximately 2.7% of anthropogenic GHG emissions.
- 3-nitrooxypropanol (3-NOP) have been shown to consistently decrease enteric methane emissions by up to 30% in both dairy and beef cattle.
- In vitro analysis suggested that the tropical/subtropical red seaweed Asparagopsis taxiformis can reduce methane production by 95% when added to feed at a 5% organic matter inclusion rate.
- An in vivo study in dairy cows using A. armata, a closely related species, showed that methane production and yield (adjusted for feed consumption) decreased 67 and 43%, respectively, at a 1% level of dry matter inclusion in the diet.
- Kinley et al. (14) reported that inclusion of A. taxiformis at 0.10 and 0.20% of dietary dry matter over a 90 day period decreased methane production in steers up to 40 and 98%, and produced weight gain improvements of 24 and 17 kg, respectively, relative to control steers.
- The concentration of bromoform in Asparagopsis was 6.55 mg/g in the study conducted by Kinley et al. (14) compared to 1.32 mg/g in the study by Roque et al. (13).
- Worldwide, seaweed farming generates more than 30 million metric tons (MMT, wet weight) of material annually.
- Based on typical dry matter intake for beef and dairy cattle, the potential volume of seaweed that would be needed to supply the 93 M U.S cattle at a 1% inclusion level is: 3-3.4 MMT dry seaweed per year.
Other Important Findings
- Seaweed can reduce methane production in cattle.
- Seaweed contains essential nutrients and secondary plant compounds that can aid ruminant reproduction.
- Seaweeds may contain inorganic elements and heavy metals that could cause toxicity.
- Seaweed farming can benefit the environment in multiple ways including providing rich habitat for fishes and carbon sequestration.
- In vitro analysis of Asparagopsis taxiformis showed a 95% reduction in methane production at a 5% organic matter inclusion rate.
- In vivo trials using A. armata showed reductions in methane production and yield at a 1% inclusion rate.
- The efficacy of methane reduction appears to correlate with the concentration of bromoform compounds.
- Seaweed can improve animal performance.
- Seaweed can improve milk quality.
Limitations Noted in the Document
- The use of seaweed in livestock diets is not widespread due to the need for regulatory approval, carbon credits, or legislative mandates.
- The high water content of seaweed requires drying prior to long-term storage and shipping.
- There is a need to develop appropriate methods for screening seaweed species before investing in large-scale cultivation.
- It is difficult for scientists to obtain the sufficient biomass from many seaweed species to conduct in vivo trials.
- The content of active compounds in wild-harvested seaweed may not be consistent.
- The variability among in vivo research trial designs has made it challenging to build a comprehensive dataset.
- The current lack of commercial availability of Asparagopsis sp. supply chain limits research.
Conclusion
The study underscores the potential of seaweed as a sustainable solution to reduce enteric methane emissions in cattle, thus contributing to a reduction in greenhouse gas emissions. It highlights the need for further research and development to address the challenges and capitalize on the opportunities associated with its utilization. The study emphasizes the importance of developing standardized methods, evaluating the sustainability and economics of seaweed production, and conducting both short- and long-term animal trials. The successful integration of seaweed-based feed ingredients requires addressing several key considerations, including consistent volume, quality, and safety of the raw materials. Furthermore, the study advocates for collaboration among researchers, industry stakeholders, and policymakers to accelerate the development of seaweed-based feed ingredients and their adoption in the livestock industry. The study emphasizes the need for comprehensive frameworks to assess the environmental, economic, and social sustainability of seaweed-based animal feeds. It concludes that the development of marketing strategies that appeal to consumers’ desire to contribute to low carbon economies and lifestyles could be a key factor in the successful integration of seaweed-based feed ingredients into the livestock industry. Finally, the study suggests that despite the promising results, challenges remain in making seaweed a widespread, economically viable, and environmentally sound solution for reducing methane emissions from cattle.