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Let’s Feed Seaweed To Cows & Reduce Their Methane Burping

Old-time solutions are reappearing as we seek to become a zero-emissions society.

How can the agriculture industry reduce the amount of methane released when cows burp? It’s been a struggle for scientists and policymakers. A new method in which farmers feed seaweed to cows — needing to incorporate only about 0.2% of the total feed intake — indicates that methane levels can be reduced by 98%. It’s a real breakthrough, as most existing solutions cut methane only by about 20% to 30%.

feed seaweed to cows

Image retrieved from NASA (public domain)

The livestock industry contributes 40% gross domestic product (GDP) of overall global agriculture. The largest agriculture greenhouse gas (GHG) contribution is from cattle and sheep production systems that are responsible for up to 18% of total global GHG emissions, mainly in the form of enteric methane (CH4).

Cows release methane from both ends: by burping and through their manure. Cows, like other ruminants including sheep, goats, and giraffes, have 4 stomach chambers. As the animals eat a mixture of hay, grass, and grains, microbes in one of the chambers, the rumen, process the food. A cow belches due to enteric fermentation, which is the digestive process of converting sugars into simple molecules for absorption into the bloodstream and which produces methane as a by-product.

Ruminants are the principal source of livestock methane emissions because they produce the most methane per unit of feed consumed.

Methane has a much higher global warming potential (GWP) than carbon dioxide. A greenhouse gas’s GWP is its ability to trap extra heat in the atmosphere over time compared to CO2. For example, the 100-year GWP of methane is 28. So, if 1 ton of methane were released into the atmosphere, it would create the same amount of warming over 100 years as 28 tons of CO.

“We need to decarbonize what we eat,” argues Brent Newell, an attorney with the Center on Race, Poverty, and the Environment.

In 2016, California passed a law requiring dairy farms to cut methane production by 40% by 2030. The biggest challenge was to figure out how to reduce emissions from the state’s 1.4 million dairy cows — the largest source of methane in the state and the biggest source of dairy-related methane in the country. Barriers to reducing methane at the time prompted a bill from state Sen. Ricardo Lara (D), which was signed into law and prohibited California from regulating methane from dairies and cattle farms until at least 2024.

Feed Seaweed to Cows & Neutralize Methane

What seems like radical new thought may, actually, not be that recent. It seems that cows have been eating seaweed for a very long time, as evidence suggests that herders in ancient Greece fed their cows seaweed, as did many in 18th century Iceland.

On Canada’s Prince Edward Island, Joe Dorgan observed that his beach-paddocked cows got pregnant faster and produced more milk than his inland pastured cows. When he retired from dairy farming in 2011, he launched a new business, North Atlantic Organics, to make “stormtoss shoreweed” available to inland farmers who graze their cows during seasons of scanty forage.

Environmental scientist Rob Kinley, working out of Dalhousie University in Nova Scotia in 2014, analyzed different varieties of seaweed that washed up on beaches, mixed in vitro with rumen microbiota, for their nutritional value and health impacts on ruminants. With an interest in how all livestock feeds affect enteric methane, they measured their samples for methane production as well. Kinley discovered in his laboratory tests that seaweeds could reduce methane production by as much as 16%.

That was the beginning.

Asparagopsis taxiformis and Asparagopsis armata are 2 species of a crimson submarine grass that drifts on waves and tides all around the world’s oceans. These 2 species are emerging as an effective tool in innovative, regenerative, and cleaner production for the wider agriculture sector. Asparagopsis and other types of seaweed have specialized gland cells that make and store bromoform, an organic compound. When this deep red seaweed is freeze-dried, powdered, and sprinkled as a garnish on a cow’s meal, bromoform blocks carbon and hydrogen atoms from forming methane in the stomach.

Kinley told the Washington Post it might just be the most promising way to eliminate methane emissions from livestock in the next decade. In their initial study, Kinley and his co-authors found that asparagopsis virtually eliminated methane emissions in lab trials. Asparagopsis inclusion resulted in a consistent and dose-dependent reduction in enteric CH4 production over time, with up to 80% CH4 mitigation at the 3% offered rate compared with the group fed no Asparagopsis (P < 0.05).

The decision to feed seaweed to cows could nearly neutralize methane emissions from their digestive processes. This is significant, as there are 1.5 billion cows on the planet, and they all emit methane in their burps.

Final Thoughts

“We’ve found something that’s been under our noses the entire time that could have one of the greatest impacts on emission reduction in the next 10 years, which is cool for people to crack but not anyone can do it,” said Sam Elsom, chief operating officer of Sea Forest, one of the upstart seaweed companies. Sea Forest grows asparagopsis in its labs in Australia.

Because seaweed absorbs carbon in the water as food, it may also help sequester carbon dioxide, another greenhouse gas, and reduce ocean acidification.

United Nations’ Food and Agriculture Organization states that mitigation interventions like the practice in which industrial agriculture feeds seaweed to cows can provide both environmental and economic benefits. Practices and technologies that reduce emissions, they say, can often simultaneously increase productivity, thereby contributing to food security and economic development.

The beef cattle production has long been considered as one of the largest sources of greenhouse gas emission. A large amount of GHGs including N2O and CH4 from enteric fermentation and manure are discharged to atmosphere during beef-production process. Research into sensitivity analysis showed that the most critical factors influencing the GHG emission included feedlot manure handling system, cattle diet, feed additives, maximum methane producing capacity, and climate — temperature, precipitation, and potential evapotranspiration.

So, while the idea of feeding seaweed to cows has hope for lessening methane, it must be noted that a substantial amount of GHGs is also emitted from many other related processes such as feed production, transportation, and energy consumption. Clearly, many additional practices need to be examined and modified to reduce the amount of regional GHGs produced from the beef cattle production process.


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Carolyn Fortuna (they, them), Ph.D., is a writer, researcher, and educator with a lifelong dedication to ecojustice. Carolyn has won awards from the Anti-Defamation League, The International Literacy Association, and The Leavy Foundation. Carolyn is a small-time investor in Tesla. Please follow Carolyn on Twitter and Facebook.


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