Red seaweed, green production

ST. CLOUD, Minn. — Reducing greenhouse gas emissions from cars and cows alike is an endeavor on the minds of some in the dairy industry. Brad Heins, a professor of organic dairy production at the University of Minnesota, shared ways the university is experimenting to reduce methane emissions from cattle at the West Central Research and Outreach Center in Morris.

Heins started his presentation at the Minnesota Organic Conference Jan. 9 at the St. Cloud River’s Edge Convention Center by sharing about a study on the effects of organic red seaweed on methane production.

The study was conducted from summer 2023 through January 2024. The research center worked with Symbrosia Inc., a Hawaii-based company that produces organic red seaweed. Their product, SeaGraze, has been in a variety of trials to determine its effect in reducing methane emissions from cattle.

“It has a higher content of bromoform and that is the compound that is used to help reduce the methane,” Heins said. “What they recommended for a rate was … a very small amount of seaweed that will help reduce the methane.”

Bromoform helps reduce methane emissions by adapting the way the cow reacts while ruminating. Instead of producing methane, a higher content of hydrogen is produced, eventually reducing the methane as the cows adjust to the diet. Cows in the study went from releasing around 100 grams of hydrogen per day to close to 700 grams.

Heins monitored the gas levels of the control group and the experimental treatment group, which were on pasture for six months and consumed the seaweed as a supplement in their grain.

Initially, there was little difference between the groups as the SeaGraze group’s rumens started to adapt to the new product. Once adaptation was complete, the experimental group began showing reduced methane. Halfway through the study, the control group was sitting at close to 400 grams of methane emitted a day while the experimental group was around 175 grams of methane a day.

The methane from cows was recorded through the use of a green feed machine. These work by capturing the methane cows burp out while they are eating grain provided to them in the machine. The machine also measures the cow’s carbon dioxide, oxygen and hydrogen alcohol levels.

As the study continued, the SeaGraze experimental group continued to stay lower than the control group with an average of 35%-40% less methane emissions, about half way through the study. Across the six months of the trial the results became less pronounced. The control group averaged 364 grams of methane a day and the SeaGraze group was around 294 grams, representing an average reduction of about 20%.

During the middle of the study, as the animals’ bodies modified to the seaweed, there was a slowing of the reduction of methane.

“It started going back because their bodies adjusted to it and started producing methane again,” Heins said. “A lot of studies with methane look at short time periods and then say, ‘We can get 40-50% reduction.’ But we don’t know what happens later. They just assume.”

The experimental group of cattle received the seaweed throughout the six months of the trial. Heins said they saw a secondary adjustment period to the seaweed where the cattle started to produce a higher amount of methane. He said it was as if the seaweed was only hindering the production of methane which caused it to be reduced.

Heins said they plan to do more studies over longer periods of time to see the longer-term effects of the seaweed.

With the cattle consuming higher levels of bromoform, bromide levels in milk also increased. The control group had a bromide level of 1.47 ng/L of milk while the other group had around 17 ng/L.

The increased level of bromide in the milk appears to have no harmful effect on humans at a normal rate of consumption. Meat harvested from cattle consuming more bromoform was also tested, showing less of an increase. 

During the study, Heins also monitored the cows’ production, components and body condition. Overall, despite the secondary adjustment period to the seaweed which resulted in an increase in methane reduction, overall, the experimental group’s data was still positive for methane reduction.

“What we had (from the SeaGraze group) was they had less intake, the same amount of milk production and less methane,” Heins said. “These cows were more efficient (during the trial).”