Farmers to feed cows seaweed to cut down on gas emissions

Feeding cows a few ounces of seaweed daily could sharply reduce their contribution to climate change

Farmers to feed cows seaweed to cut down on gas emissions

Methane is a short-lived but powerful greenhouse gas and the second-largest contributor to climate change after carbon dioxide. And the majority of human-induced methane emissions comes from livestock.

About 70% of agricultural methane comes from enteric fermentation – chemical reactions in the stomachs of cows and other grazing animals as they break down plants. The animals burp out most of this methane and pass the rest as flatulence.

There are roughly 1 billion cattle around the world, so reducing enteric methane is an effective way to reduce overall methane emissions.

But most options for doing so, such as changing cows’ diets to more digestible feed or adding more fat, are not cost-effective.

A 2015 study suggested that using seaweed as an additive to cattle’s normal feed could reduce methane production, but this research was done in a laboratory, not in live animals.

We study sustainable agriculture, focusing on livestock. In a newly published study, we show that using red seaweed (Asparagopsis) as a feed supplement can reduce both methane emissions and feed costs without affecting meat quality. If these findings can be scaled up and commercialized, they could transform cattle production into a more economically and environmentally sustainable industry.

Cows’ special digestive system is a major methane brewer.

Plant-digesting machines

Ruminant animals, such as cows, sheep and goats, can digest plant material that is indigestible for humans and animals with simple stomachs, such as pigs and chickens. This unique ability stems from ruminants’ four-compartment stomachs – particularly the rumen compartment, which contains a host of different microbes that ferment feed and break it down into nutrients.

This process also generates byproducts that the cow’s body does not take up, such as carbon dioxide and hydrogen. Methane-producing microbes, called methanogens, use these compounds to form methane, which the cow’s body expels.

We first analyzed this problem in a 2019 study, the first such research that was conducted in cattle rather than in a laboratory.

In that work, we showed that supplementing dairy cows’ feed with about 10 ounces of seaweed a day reduced methane emissions by up to 67%.

However, the cattle that ate this relatively large quantity of seaweed consumed less feed. This reduced their milk production – a clear drawback for dairy farmers.

Our new study sought to answer several questions that would be important to farmers considering whether to use seaweed supplements in their cattle.

We wanted to know whether the seaweed was stable when stored for up to three years; whether microbes that produce methane in cows’ stomachs could adapt to the seaweed, making it ineffective; and whether the type of diet that the cows ate changed the seaweed’s effectiveness in reducing methane emissions. And we used less seaweed than in our 2019 study.

A steer eats alfalfa pellets as equipment measures his gas emissions, including methane. Breanna Roque, CC BY-ND

Better growth with less feed

For the study, we added 1.5 to 3 ounces of seaweed per animal daily to 21 beef cows’ food for 21 weeks. As with most new ingredients in cattle diets, it took some time for the animals to get used to the taste of seaweed, but they became accustomed to it within a few weeks.

Cattle in the study adjusted quickly to seaweed supplements in their food. Breanna Roque, CC BY-ND

As we expected, the steers released a lot more hydrogen – up to 750% more, mostly from their mouths – as their systems produced less methane. Hydrogen has minimal impact on the environment. Seaweed supplements did not affect the animals’ carbon dioxide emissions.

We also found that seaweed that had been stored in a freezer for three years maintained its effectiveness, and that microbes in the cows’ digestive systems did not adapt to the seaweed in ways that neutralized its effects.

We fed each of the animals three different diets during the experiment. These rations contained varying amounts of dried grasses, such as alfalfa and wheat hay, which are referred to as forage. Cattle may also consume fresh grass, grains, molasses and byproducts such as almond hull and cotton seed.

Methane production in the rumen increases with rising levels of forage in cows’ diet, so we wanted to see whether forage levels also affected how well seaweed reduced overall methane formation.

Methane emissions from cattle on high-forage diets decreased by 33% to 52%, depending on how much seaweed they consumed. Emissions from cattle fed low-forage diets fell by 70% to 80%.

This difference may reflect lower levels of an enzyme that is involved in producing methane in the guts of cattle-fed low-fiber diets.

One important finding was that the steers in our study converted feed to body weight up to 20% more efficiently than cattle on a conventional diet. This benefit could reduce production costs for farmers, since they would need to buy less feed.

For example, we calculate that a producer finishing 1,000 head of beef cattle – that is, feeding them a high-energy diet to grow and add muscle – could reduce feed costs by US$40,320 to $87,320 depending on how much seaweed the cattle consumed.

Global methane sources include fossil fuel and biomass combustion, agriculture (mainly livestock), the breakdown of waste in landfills and natural decomposition in wetlands. Jackson et al., 2020, CC BY

We don’t know for certain why feeding cattle seaweed supplements helped them convert more of their diet to weight gain. However, previous research has suggested that some rumen microorganisms can use hydrogen that is no longer going into methane production to generate energy-dense nutrients that the cow can then use for added growth.

When a panel of consumers sampled meat from cattle raised in our study, they did not detect any difference in tenderness, juiciness or flavor between meat from cattle that consumed seaweed and others that did not.

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Commercializing seaweed as a cattle feed additive would involve many steps. First, scientists would need to develop aquaculture techniques for producing seaweed on a large scale, either in the ocean or in tanks on land. And the U.S. Food and Drug Administration would have to approve using seaweed as a feed supplement for commercial cattle.

Farmers and ranchers could also earn money for reducing their cattle’s emissions. Climate scientists would have to provide guidance on quantifying, monitoring and verifying methane emission reductions from cattle. Such rules could allow cattle farmers to earn credits from carbon offset programs around the world.


Feeding Cows Seaweed Could Reduce Their Contribution to Climate Change

Farmers to feed cows seaweed to cut down on gas emissions


The Eiffel Tower in Paris, France, is among the major landmarks that will turn off its lights for Earth Hour on March 27, 2021. Antoine Antoniol / Getty Images

“Our goal is simple,” organizers wrote. “Put the spotlight on our planet and make it the most watched video in the world on March 27 (or beyond!) so that as many people as possible hear our message.”

The virtual spotlight comes about a year into the coronavirus pandemic, as many countries remain under some type of safety regulation. While COVID-19 necessitates an online celebration, it also reflects the importance of protecting the natural world.

“Protecting nature is our moral responsibility but losing it also increases our vulnerability to pandemics, accelerates climate change, and threatens our food security,” WWF International Director General Marco Lambertini said in a press release. “We must stop taking nature for granted, respect its intrinsic value, and — importantly — value the crucial services it provides to our health, wellbeing and economy.”

Tick. Tock. Tick. Tock.


Can Seaweed Cut Methane Emissions on Dairy Farms?

Farmers to feed cows seaweed to cut down on gas emissions
12 August 2020

Seaweed may be the super food dairy cattle need to reduce the amount of methane they burp into the atmosphere.

Early results from research at the University of California-Davis, indicate that just a touch of the ocean algae in cattle feed could dramatically cut greenhouse gas emissions from California’s 1.8 million dairy cows.

“This is a very surprising and promising development,” said animal science professor and Sesnon Endowed Chair Ermias Kebreab inside the UC Davis dairy barn where he is testing seaweed efficacy with 12 Holstein cows.

“Results are not final, but so far we are seeing substantial emission reductions.

This could help California’s dairy farmers meet new methane-emission standards and sustainably produce the dairy products we need to feed the world.”

Kebreab’s project is the first to test seaweed on live dairy cattle anywhere in the world.

His team will publish preliminary findings in late June and begin further tests with additional cattle later this summer.

A question of digestion

Cows and other “ruminant” animals goats and sheep burp continuously throughout the day as they digest food in their rumen, the first of four sections of their stomachs. The rumen is home to millions of microbes that help ferment and break down high-fiber food grass and hay. This fermentation produces gases that combine to form methane, an especially potent heat-trapping gas.

So, as cattle perpetually burp and exhale, they emit methane. Cows also pass methane gas from the other end, but to a much lesser degree. Manure, too, is a source of methane emissions.

In an effort to reduce greenhouse gas emissions, California legislators recently adopted regulations requiring dairy farmers and other producers to cut methane emissions 40 percent by 2030.

“Since much of a dairy’s methane emissions come from the animal itself, nutrition can play a big role in finding solutions,” said Kebreab.

Molasses, please

Testing supplements in cattle feed is not new. Kebreab and his colleagues at UC Davis and beyond are finding varying degrees of success with a wide range of feed additives. Some compounds work in the lab with simulated cattle digestive systems, but not with live animals. Researchers in England, for example, found success with curry supplements until they tested it with live cattle.

“The cows didn’t the curry,” Kebreab said.

During lab tests last year, researchers in Australia found that just 2 percent seaweed in cattle feed could reduce methane emissions by 99 percent. The seaweed apparently inhibits an enzyme that contributes to methane production.

Judging from the reaction of the UC Davis cows, the seaweed is so far, so good — especially when cut with a bit of molasses.

“The molasses masks the smell,” Kebreab said, smiling as two Holsteins nudged a gate that opens when it’s time for their next meal. “They enjoy their feed.”

To test seaweed efficacy, Kebreab and animal nutrition graduate student Breanne Roque have separated 12 cows into three groups. Two groups are fed with different doses of seaweed, and one group’s feed has no seaweed at all. They rotate through the two-week feeding regimens with a weeklong seaweed fast in between.

Four times a day, cows get a snack from an open-air contraption that measures the methane in their breath as they eat the treat.

“The numbers we’re seeing are amazing — well beyond the target that farmers will need to reach,” Kebreab said.

Throughout the seaweed diet, the cows’ milk is tested for qualities yield, flavor and nutritional content.

A love of milk

Sustainable dairy production is not just an academic endeavor for Kebreab. He has loved milk since he was a young boy growing up in Eritrea, a country in the Horn of Africa.

“I was always amazed at how an animal that eats grass can produce such a high-quality food,” Kebreab said. “And I loved the taste. We didn’t get that much — maybe once or twice a week. I wondered, can we find a way to produce enough milk for everyone?”

Kebreab is trying.

Among his many projects, Kebreab recently received a $500,000 grant to help improve sustainable livestock production in Ethiopia and Burkina Faso, where dairy cattle produce 5 to 10 liters of milk per day compared to the 45 liters that cows in California can produce. He is working with researchers and funding from the University of Florida with support from the Bill and Melinda Gates Foundation.

“By improving the quality and quantity of dairy production in developing countries, we help families rise from poverty and malnutrition, and also reduce the carbon footprint of cattle worldwide,” Kebreab said.

If seaweed proves to be a climate-smart supplement, producing it could be environmentally friendly, too. As Kebreab notes, “Growing seaweed doesn’t require land, fresh water or fertilizer.”

But there is still a lot to learn before farmers should consider feeding cattle seaweed.

“We have much more research to do to determine if seaweed supplements could provide a viable, long-term solution,” Kebreab said. “But we are very encouraged by these early results.”

Feed/Nutrition/Forage, Environment and Waste, Sustainability, General


Feeding Cattle Seaweed Reduces Their Greenhouse Gas Emissions 82 Percent

Farmers to feed cows seaweed to cut down on gas emissions

A bit of seaweed in cattle feed could reduce methane emissions from beef cattle as much as 82 percent, according to new findings from researchers at the University of California, Davis. The results, published today (March 17) in the journal PLOS ONE, could pave the way for the sustainable production of livestock throughout the world.

“We now have sound evidence that seaweed in cattle diet is effective at reducing greenhouse gases and that the efficacy does not diminish over time,” said Ermias Kebreab, professor and Sesnon Endowed Chair of the Department of Animal Science and director of the World Food Center. Kebreab conducted the study along with his Ph.D. graduate student Breanna Roque.

“This could help farmers sustainably produce the beef and dairy products we need to feed the world,” Roque added.

Over the course of five months last summer, Kebreab and Roque added scant amounts of seaweed to the diet of 21 beef cattle and tracked their weight gain and methane emissions.

Cattle that consumed doses of about 80 grams (3 ounces) of seaweed gained as much weight as their herd mates while burping out 82 percent less methane into the atmosphere.

Kebreab and Roque are building on their earlier work with dairy cattle, which was the world’s first experiment reported that used seaweed in cattle.  

Less gassy, more sustainable

Greenhouse gases are a major cause of climate change, and methane is a potent greenhouse gas. Agriculture is responsible for 10 percent of greenhouse gas emissions in the U.S., and half of those come from cows and other ruminant animals that belch methane and other gases throughout the day as they digest forages grass and hay.

Since cattle are the top agricultural source of greenhouse gases, many have suggested people eat less meat to help address climate change. Kebreab looks to cattle nutrition instead.

“Only a tiny fraction of the earth is fit for crop production,” Kebreab explained. “Much more land is suitable only for grazing, so livestock plays a vital role in feeding the 10 billion people who will soon inhabit the planet. Since much of livestock’s methane emissions come from the animal itself, nutrition plays a big role in finding solutions.”

In 2018, Kebreab and Roque were able to reduce methane emissions from dairy cows by over 50 percent by supplementing their diet with seaweed for two weeks. The seaweed inhibits an enzyme in the cow’s digestive system that contributes to methane production.

In the new study, Kebreab and Roque tested whether those reductions were sustainable over time by feeding cows a touch of seaweed every day for five months, from the time they were young on the range through their later days on the feed lot.

Four times a day, the cows ate a snack from an open-air contraption that measured the methane in their breath. The results were clear. Cattle that consumed seaweed emitted much less methane, and there was no drop-off in efficacy over time.

Next steps

Results from a taste-test panel found no differences in the flavor of the beef from seaweed-fed steers compared with a control group. Similar tests with dairy cattle showed that seaweed had no impact on the taste of milk. 

Also, scientists are studying ways to farm the type of seaweed — Asparagopsis taxiformis — that Kebreab’s team used in the tests. There is not enough of it in the wild for broad application.

Another challenge: How do ranchers provide seaweed supplements to grazing cattle on the open range? That’s the subject of Kebreab’s next study.

Kebreab and Roque collaborated with a federal scientific agency in Australia called the Commonwealth Scientific and Industrial Research Organization, James Cook University in Australia, Meat and Livestock Australia, and Blue Ocean Barns, a startup company that sources, processes, markets and certifies seaweed-based additives to cattle feed. Kebreab is a scientific adviser to Blue Ocean Barns.

“There is more work to be done, but we are very encouraged by these results,” Roque said. “We now have a clear answer to the question of whether seaweed supplements can sustainably reduce livestock methane emissions and its long term effectiveness.”

Support for the research comes from Blue Ocean Barns, the David and Lucile Packard Foundation and the Grantham Foundation.


Carbon farming: reducing methane emissions from cattle using feed additives

Farmers to feed cows seaweed to cut down on gas emissions

In Australia, direct livestock emissions account for about 70% of greenhouse gas emissions by the agricultural sector and 11% of total national greenhouse gas emissions.

This makes Australia’s livestock the third largest source of greenhouse gas emissions after the energy and transport sectors.

Livestock are the dominant source of methane (CH4) and nitrous oxide (N2O), accounting for 56% and 73%, respectively, of Australia’s emissions.

How methane is produced by ruminants

Ruminant livestock – cattle, sheep, buffalo, goats, deer and camels – have a fore-stomach (or rumen) containing microbes called methanogens, which are capable of digesting coarse plant material and which produce methane as a by-product of digestion (enteric fermentation): this methane is released to the atmosphere by the animal belching.

The amount of methane emitted by livestock is primarily driven by the number of animals, the type of digestive system they have and the type and amount of feed consumed. Ruminants are the principal source of livestock methane emissions because they produce the most methane per unit of feed consumed.

How feed additives work

Methane-reducing feed additives and supplements inhibit methanogens in the rumen, and subsequently reduce enteric methane emissions.  

Methane-reducing feed additives and supplements are most effective when grain, hay or silage is added to the diet, especially in beef feedlots and dairies.

What are methane-reducing feed additives or supplements?

Methane-reducing feed additives and supplements can be:

  • synthetic chemicals
  • natural supplements and compounds, such as tannins and seaweed
  • fats and oils.

Synthetic chemicals, such as antibiotics, are sometimes used to improve the efficiency of feed conversion in cattle, although it is not a recommended practice to use these additives to reduce methane emissions. There are legislative restrictions and human health concerns about using antibiotics as growth promotants in livestock.

There is potential for natural compounds and materials to reduce methane production in livestock, though these products have not been widely commercialised. Feeding one type of seaweed at 3% of the diet has resulted in up to 80% reduction in methane emissions from cattle.

Fats and oils show the most potential for practical application to farming systems and have shown methane emission reductions of 15–20%.

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Carbon benefits

There are 2 approved methodologies under the Emissions Reduction Fund (ERF) for using feed additives or supplements to reduce methane emissions and claim carbon credits.

Adding nitrates to the diet at a specified rate optimises rumen fermentation, and changes the pathway of hydrogen to produce ammonia rather than methane. This can have the dual effect of reducing methane emissions while improving or maintaining animal performance. We recommend that producers seek specialist advice before using this option because overdosing can result in nitrate poisoning.

In the approved methodology for feeding nitrates to beef cattle, nitrate salt licks are substituted for animals previously fed urea, and is potentially applicable outside of feedlots.

The use of dietary additives is currently approved only for grazing milking cows, and includes the addition of eligible additives to increase fat content of the diet to reduce methane emissions. 

Co-benefits to using feed additives

There are several benefits:

  • The reduced volume of methane formation may lead to better efficiency of feed utilisation, given that methane emissions represent a gross energy loss from feed intake of about 10%.
  • Addition of fats and oils to the diet are a source of energy to the animal, as well as reducing methane.

Opportunities to use feed additives or supplements:

  • Reduction of methane emissions through feed additives, such as fats and oils, can reduce methane production by about 18% and offer energy and protein to the animal. For a 600 cow dairy herd (producing 100kg of methane per head per year) methane emissions could be reduced by 372 tonnes of carbon dioxide equivalent per year.
  • Reducing methane emissions is deemed ‘additional’ to normal management practices.

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Risks from using feed additives or supplements to reduce methane emissions

There are several risks:

  • The amount of additive ingested by livestock in paddock grazing systems is hard to regulate. Feed additives are more effective in feedlots and dairies.
  • Toxicity leading to ill health or death of livestock can result if nitrate supplements are introduced suddenly or ingestion is too high.
  • Long-term and consistent positive production responses to the addition of feed additives have not been found. These responses are essential for the commercial application of feed additives.
  • Fluctuations in carbon price may result in reduced or lost profit margins in a carbon farming project.

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