Kelp wanted: Why researchers are adding seaweed to cattle's diet

Cows are not known to have seafood in their diet, but a team of federal scientists in Nova Scotia started introducing some to seaweed in hopes it could help in the fight against climate change.

The focus? The cattle's burps. 

The Agriculture and Agri-Food Canada project involved feeding 16 cows varying amounts of seaweed at a research farm in Nappan, N.S. It found that by replacing only one percent of the cows' regular feed with kelp, researchers discovered that it reduced the methane emissions from cow burps by as much as 15 percent.

"That's a fairly significant result," said John Duynisveld, the lead biologist.

He said when cows consume food, it enters the first stomach, called the rumen, where various microbes break down the food. That process results in methane, a greenhouse gas linked to global warming, which gets released through burps.

Bryanna Richardson, one of the researchers, said to measure the emissions, they put the cows in respiratory chambers connected to a computer system that tracked gases coming from the animals. 

First the cows needed to get used to the chambers, which is why researchers left them in the room for a few hours at a time. Eventually they were left there for 24 hours straight so their daily methane emissions could be tracked.

"There's a vacuum pump that's attached to it [the chamber] and it pulls all the air that they're breathing out up into the computer system, which measures methane, carbon dioxide and oxygen," said Richardson. 

Kelp contains bio-components such as tannins that Duynisveld said might be changing the composition of cow's burps. Meaning the cows he studied didn't belch less, but their burps were less potent. 

Duynisveld said on average, a beef cow emits approximately 100 kilograms of methane annually, so this research aimed to make a small contribution toward addressing climate change. 

Methane, which is produced by the agriculture industry, landfills and oil and gas activities, is responsible for about 14 per cent of Canada's greenhouse gas emissions

Shannon Arnold, with the marine program at the Ecology Action Centre in Halifax, said the study is different from others done internationally as it focuses on using locally sourced kelp species that could be farmed with a reduced ecological impact. 

Duynisveld's study used kelp that comes from the North Shore of Prince Edward Island and some areas of Nova Scotia, commonly known as shore weed. 

Arnold said shore weed can be easily farmed locally with little land-use disruption, and she'd like to see more collaboration between cattle farms and local kelp growers.

She said the cultivation of kelp is relatively simple, as it can be grown in small spaces, with the potential to harvest around 10 kilograms of kelp per meter. Growing it could have the added benefit of being a substitute for some more environmentally burdensome crops and fertilizers, she said.

"There's lots of interest [in kelp] from new farmers and small farmers and folks all around our coastal areas," Arnold said. "This would be a great opportunity."