BURLINGTON — Researchers at the University of Vermont are looking to the ocean to try to reduce the impact that cows have on climate change.
With the help of a mechanism that mimics bovine digestion, Dr. Sabrina Greenwood, a professor with UVM’s department of animal and veterinary sciences, is teaming up with colleagues in coastal Maine to figure out if seaweed can reduce the methane emissions of cows.
The idea has been gaining traction in recent years. A 2018 study at the University of California, Davis, found that a dozen cows fed a particular type of seaweed recorded methane output reductions of 24% to 58%.
Methane, a greenhouse gas, is 34 times more harmful to the environment than carbon dioxide over a 100-year period, a United Nations climate report says. Agriculture systems account for about 10% of global greenhouse gas emissions.
Greenwood, a ruminant nutritionist, became involved with the research after the Bigelow Laboratory for Ocean Sciences in East Boothbay, Maine, received a $3 million grant in October to fund the work. The project’s leader at Bigelow, Nichole Price, emailed a colleague of Greenwood’s in hopes of connecting with a ruminant nutritionist in Vermont, Greenwood said.
“She recognized the importance of dairy in Vermont and [her email] got forwarded to me and I said ‘Yeah, let’s talk,’” Greenwood said.
Greenwood’s research involves the use of six 6-liter continuous culture fermenters, which Greenwood described as a “suped up beaker.” The fermenters, with some slight alterations made to them, mimic the rumen of a cow, or the chamber of a cow’s stomach that houses most of the digestive microbes and bacteria.
Greenwood and the half dozen students who work with her introduce various components to the beaker to create the desired effect. This includes introducing carbon dioxide gas to remove any oxygen, wrapping the beakers in a heat blanket to keep it at the same temperature as the inside of a cow, reducing light pollution and creating fake saliva.
The last ingredient is rumen fluid. Greenwood said some cows at UVM’s farm have a fistula in their side. The surgically implanted device creates an opening on the side of the cow, so Greenwood and her students can reach inside the cow’s rumen and collect the fluid needed.
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“When you’re testing out new feed, it’s often very nice to test them on these kinds of systems before you move them to an animal,” Greenwood said.
One particular microbe in the rumen, methanogens, produce the most methane in cows, Greenwood said.
It’s a common misconception that cows flatulate all their methane, she said. In fact, about 85% of methane released by cows actually comes from their belching, because the methanogens are located in the rumen, the first chamber of the stomach.
Seaweeds have compounds that researchers believe can interfere with the way that cows produce methane, she said.
Price’s team at Bigelow is working to identify which types of seaweed could have the greatest effect on reducing cows’ methane output while also working to grow them sustainably as part of Maine’s large aquaculture industry.
Greenwood said Bigelow is working with thousands of different types of seaweed to understand better how they break down, what their potential methane output could be and the presence of any metals which may have been picked up in the ocean.
Once Bigelow researchers find a few promising seaweeds, they will partner with regional aquaculturalists to send samples to Greenwood and her team. Greenwood will then determine a potential diet ratio, usually 1% to 2% of body weight, and introduce the different types of seaweed and measure the methane output. She plans to repeat this process many times over until she gets a consistent result.
The research aims to figure out how much and what types of seaweed in cow feed would have the desired effect on methane output, without compromising the nutritional needs of cows.
When Greenwood finishes her research, which she hopes will be complete by the end of the summer, she will send the results back to Bigelow, where there is a microbiologist on staff. The microbiologist will then analyse how the microbes in the artificial rumen interacted with the seaweed.
Once the specific types of seaweed are selected for testing in real cows, Wolfe’s Neck Center for Agriculture and the Environment in Freeport, Maine, and the Organic Dairy Research Farm at the University of New Hampshire will begin feeding it to their herds.
“They’re going to feed it to herds and they’re going to do that likely in comparison with kelp meals that are already out there to see if these are better candidates…from a methane perspective,” Greenwood said.
Greenwood said these tests are crucial to understanding how a seaweed diet affects cows over time. The fermenters Greenwood has in her lab mimic only the rumen, and she said researchers need to determine if milk or reproductive systems could be impacted by the changing diet. Cows at Wolfe’s Neck and UNH are expected to start on a seaweed diet either later this year, or in 2021.
None of the cows at UVM will be fed seaweed as part of the study. Their primary contribution to the research is their rumen fluid for Greenwood’s culture fermenters.
Greenwood said she wants to strike a balance between feeding cows seaweed and the environmental impact involved with getting seaweed to farms. Seaweed would need to be shipped to landlocked states which, over a long enough distance, could counteract the net impact of methane reduction on the farm.
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Greenwood said the dairy industry “sometimes get the short end of the stick” in climate change discussions. She said over the past decade, dairy farmers have been working much harder to reduce waste and runoff on their farms.
“This isn’t a silver bullet,” she said. “If the dairy industry were to miraculously find some sort of product, like seaweed, that could completely knock out methane emissions, it doesn’t solve the world’s climate problem. There’s a lot more beyond that.”
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