Wednesday 19 July 2023

Red alga added to cow poop slashes methane emissions by almost half


A particularly impressive red alga has already shown great promise in dramatically reducing the alarming levels of methane gas produced by a cow's enteric digestive system. Now, a team of scientists has moved from the animal's belches to its tail end, in an effort to get to the bottom of the methane produced in the poop.

Researchers in Sweden found that by adding the tropical Asparagopsis taxiformis (AT), also known as red sea plume, to cow feces, it cut methane production in the poop by nearly half.

While feces emits a fraction of the methane that is produced when the animal ruminates, it still accounts for around 10% of the gas released into the atmosphere in the US. Cows, overall, produce around 37% of the overall methane emissions.

According to the US Department of Agriculture, an estimated 90 million head of cattle are consistently farmed across the country.

“We showed that adding AT to the feces of dairy cows significantly reduced methane production from the feces by 44% compared to feces without AT,” said Mohammad Ramin, an animal science researcher at the Swedish University of Agricultural Sciences. “It also turned out that methane production from feces of cows that had been supplemented with AT in their diet was not lower than from the feces of cows that had not been fed the alga.”

It all comes down to the alga’s main compound, bromoform, which naturally blocks the process of methane gas generation. However, this is the first time scientists have dug around in dung to test the plant’s power.

“There have been many studies using AT in dairy cows’ diets to reduce enteric methane production,” Ramin said. “However, no studies have reported on the decrease of methane emissions from manure.”

One of the concerns of tackling the issue from the front end is that AT is high in iodine. In dairy cattle, this has the potential to elevate iodine levels in the milk produced, which can cause issues such as thyroid problems and at the extreme end prove toxic.

Researchers are working on engineering a strain of AT with less iodine.

And while methane only makes up around 20% of greenhouse gas emissions, behind carbon dioxide, it’s at least 25 times more efficient at being able to trap heat in the atmosphere.

“Manure methane production does contribute to global greenhouse gas emission and needs to be reduced,” Ramin said. “Our study showed a potential way how methane inhibitors could be utilized to do that.”

While this was a small study, scientists hope it will pave the way for others to look into how AT acts on halting methane production in poop.

The research was published in the journal Frontiers in Sustainable Food Systems.

Source: Swedish University of Agricultural Sciences via EurekAlert

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