When cows belch, they rarely beg anyone’s pardon. Bovine manners aside, the gastrointestinal process in play is odious twice over. Cow burps smell, and they release methane into the air, a gas that is 30 to 80 times more effective than carbon dioxide at warming the earth’s atmosphere.

A cow’s stomach, like that of all ruminants, has four chambers. The first is called the rumen, and it serves as a methane-producing fermentation vat. When a cow swallows its food, the grass, hay or grain mingles with the microbes in the rumen until the animal regurgitates it through its handy bi-directional esophagus and re-chews it as cud. This process recurs dozens of times a day, and each time it spews methane into the air.

Other naturally occurring sources of methane include most ruminants’ manure; termites working through piles of decaying wood; and microbe-rich wetlands, like bogs and swamps. Methane emissions attributed to human activities include man-made rice patties; thawing permafrost and burning landscapes due to climate change; municipal landfills and wastewater treatment plants; and leaking natural gas and oil drilling sites. But given the estimated 1.4 billion cattle (dairy and beef, combined) worldwide, they are the source of as much as 40 percent of the world’s annual methane emissions.

Could seaweed supplements be the solution? Preliminary results from studies conducted by agriculture scientists in Australia, California, Texas and Pennsylvania have shown that sprinkling a little Asparagopsis taxiformis into a cow’s diet can reduce methane emissions in dairy cows by more than 50 percent. Asparagopsis taxiformis is a subtropical species of red algae native to Australia and the Hawaiian Islands, and found in small quantities in southern California; experts doubt the wild supply is large enough to relieve cow belching worldwide.

“We will need to turn to seaweed farming to help solve the problem, and we do that really well here in Maine,” said Nicole Price, senior research scientist at Bigelow Laboratory for Ocean Scientists in East Boothbay. Bigelow Laboratory is also home to the national Center for Marine Algae and Microbiota, which maintains the largest, most diverse collection of publicly available marine algal strains in the world.

But Asparagopsis taxiformis has two serious drawbacks for Mainers trying to tackle climate change: First, it doesn’t grow well in the Gulf of Maine. Next, we wouldn’t want it to because it’s a highly invasive species; if it gained a foothold it could harm the gulf’s marine ecosystem. Price is testing about a dozen seaweeds native to Maine waters that contain the bioactive substances known to reduce methane production in cows – mainly bromoform and phlorotannins.


“We’re not looking for a single seaweed that will curb methane production in a cow’s gut completely. It’s going to be a matter of getting the right blend of multiple seaweeds to accomplish the highest possible reduction without adversely affecting the health of the animal,” Price said.

As she works on developing the right blend, she uses a table-top cow gut simulator to test the efficacy of each concoction. Price also tests how much of each customized Maine seaweed cocktail – typically between half of one percent to two percent of a cow’s daily intake – does the trick.

In soup, a sprinkle of seaweed gives depth of flavor. Shawn Patrick Ouellette/Staff Photographer

Bigelow recently received a $3.1 million grant from the Shelby Cullom Davis Charitable Fund to move testing of Price’s seaweed blends into the field next summer. To pull off the field testing, Bigelow is working with Colby College, the University of New Hampshire, Wolfe’s Neck Center for Agriculture & the Environment, and the University of Vermont. Price said the team will employ feeding machines to dispense the seaweed-laced food; the seaweed likely will be dried and then ground before it’s added to the feed.

The cows voluntarily visit these machines, and a mechanism measures the methane emissions while they eat. The team will track methane emissions of about 40 dairy cows over 10 weeks; assess changes in milk production, composition and taste; examine the possible effects seaweed residue in the cows’ manure might have on other agriculture operations; and weigh the economic feasibility of the supplements given the tight financial margins of the dairy industry.

Sen. Angus King is one Maine eater excited about the role cows’ seafood diet may play in reducing greenhouse gas emissions. Speaking at a recent event at Wolfe’s Neck Center on agriculture and climate change, King said climate change won’t be solved by a silver bullet. Rather it’s going to require a spray of silver buckshot.

Could a seaweed diet for cows one day be one of those silver pellets?


CHRISTINE BURNS RUDALEVIGE is a food writer, recipe developer and tester and cooking teacher in Brunswick, and the author of “Green Plate Special,” a cookbook from Islandport based on these columns. She can be contacted at cburns1227@gmail.com.


Beef, Mushroom, Seaweed and Noodle Soup

Serves 4

4 cups mushroom or beef broth

2 tablespoons mixed seaweed flakes


1 (8-ounce) steak

Salt and pepper

4 heaping cups cooked noodles (about 8 ounces dried or 16 ounces fresh noodles)

4 tablespoons vegetable oil

2 cups sliced mixed mushrooms

1 tablespoon minced ginger root


1 tablespoon minced garlic

1 tablespoon sambal oelek

2 cups curly kale, ripped into bite-sized pieces

Combine the broth and seaweed in a medium saucepan and simmer for 30 minutes.

Season the steak with salt and pepper. Toss the noodles with 1 tablespoon oil and set aside.

Heat 1 tablespoon of the oil over medium high heat in a medium skillet. Place the steak into the hot pan. Sear on one side for 4 minutes. Flip and cook on the second side until it’s done to your liking. Remove the steak from the pan and set it aside to rest.

Add the remaining 2 tablespoons of the oil to the now empty pan. Stir in the mushrooms and cook undisturbed until they brown on one side, 4-5 minutes. Add the ginger, garlic, sambal oelek and kale. Stir continuously until the kale is wilted. Add the noodles and stir to heat them through, 4-5 minutes.

Slice the steak very thinly.

Divide the noodles, vegetables and sliced steak between 4 bowls. Ladle the broth over and serve immediately.

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