Seaweed Feed Supplement May Not be a Viable Option to Fight Climate Change

According to researchers at Pennsylvania State University (Penn State), using seaweed in the place of cattle feed may considerably reduce methane gas belched by livestock.

Cows in the study at the Penn State dairy barns, to eat a sweet treat, put their heads in devices that measure methane they belch. The average dairy cow burps about 380 pounds of methane a year. Early studies show that supplementing their feed with seaweed could mitigate 80% of the potent greenhouse gas. (Image credit: Hristov Research Group/Penn State)

However, the researchers also warn that this practice may not provide a viable approach to fight climate change.

Asparagopsis taxiformis—a red seaweed that grows in the tropics—in short-term studies in lactating dairy cows decreased methane emission by 80 percent and had no effect on feed intake or milk yield, when fed at up to 0.5 percent of feed dry-matter intake. It looks promising, and we are continuing research.

Dr Alexander Hristov, Distinguished Professor of Dairy Nutrition, Penn State

If seaweed feed supplement provides a feasible alternative to make a difference at a global level, then the production scale would have to be considerably huge, stated Hristov. Globally, there are almost 1.5 billion head of cattle, which means it is not possible to harvest sufficient amounts of wild seaweed to add to the animals’ feed. Moreover, providing this seaweed as a supplement to most of the 94 million cattle in the United States is truly unrealistic.

To be used as a feed additive on a large scale, the seaweed would have to be cultivated in aquaculture operations,” he stated. “Harvesting wild seaweed is not an option because soon we would deplete the oceans and cause an ecological problem.”

Despite this fact, Asparagopsis taxiformis has the potential to reduce enteric methane as a feed supplement and hence requires a great deal of attention, stated Hannah Stefenoni, a graduate student working with Hristov on the study project. Stefenoni will present the study to members of the American Dairy Science Association June 23rd, 2019, at their annual meeting in Cincinnati in Ohio. The results of the study have been recently reported online in the Proceedings of the 2019 American Dairy Science Association Meeting.

We know that it is effective in the short term; we don't know if it's effective in the long term. The microbes in cows’ rumens can adapt to a lot of things. There is a long history of feed additives that the microbes adapt to and effectiveness disappears. Whether it is with beef or dairy cows, long-term studies are needed to see if compounds in the seaweed continue to disrupt the microbes' ability to make methane.

Dr Alexander Hristov, Distinguished Professor of Dairy Nutrition, Penn State

Moreover, there are concerns regarding the stability of bromoforms—the active ingredients in the seaweed—over time. Such compounds are responsive to sunlight and heat and have a tendency to lose their methane-mitigating activity with storage and processing, warned Hristov.

Another question is palatability because cows do not appear to like the taste of seaweed. When 0.75% of Asparagopsis taxiformis was included in the diet, the team noticed a significant drop in the feed intake by the livestock.

The long-term impacts of seaweed on the reproduction and health of animals and its impact on the quality of meat and milk also need to be established. Hristov further added that a panel judging milk taste is part of the ongoing study.

Within the United States, cows burping methane gas and contributing to climate change has been a topic of significant ridicule, admitted Hristov, who is known as an international expert in performing studies that assess the emissions of greenhouse gases from animal agriculture. In other countries, it is taken seriously because every year, the average dairy cow belches about 380 pounds of the powerful greenhouse gas, explained Hristov.

But methane from animal agriculture is just 5 percent of the total greenhouse gases produced in the United States—much, much more comes from the energy and transportation sectors. So, I think it's a fine line with the politics surrounding this subject. Do we want to look at this? I definitely think that we should, and if there is a way that we can reduce emissions without affecting profitability on the farm, we should pursue it.

Dr Alexander Hristov, Distinguished Professor of Dairy Nutrition, Penn State

And there might be a hidden advantage.

It is pretty much a given that if enteric methane emissions are decreased, there likely will be an increase in the efficiency of animal production,” added Hristov.

The seaweed utilized in the Penn State study was obtained from the Atlantic Ocean in the Azores and delivered in a frozen form from Portugal. Later, the researchers freeze-dried and ground it. Freeze-drying and grinding four tons of seaweed for the study was “a huge undertaking,” said Hristov.

Other researchers who were also involved in the Penn State study were Susanna Raeisaenen and Audino Melgar Moreno, graduate assistants; Molly Young, a research technician; and all in animal science. Also involved in the project was Camila Lage, a graduate student at Federal University of Minas Gerais, Brazil.

The study was funded by the U.S. Department of Agriculture’s National Institute of Food and Agriculture and the Jeremy and Hannelore Grantham Environmental Trust.

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