The world is home to about 1.5 billion cows, most of them bred and raised for the meat and dairy industry. Each of them has a quadripartite stomach, whose largest section is called rumen. An adult cow’s rumen can hold about 150 to 200 litres, and is populated by a staggering collection of microorganisms (25 billion bacteria per gram of volume), tasked with breaking down vegetal fibres through fermentation. A byproduct of rumen fermentation is hydrogen; a specific bunch of rumen-dwelling microbes, called methanogens, convert that hydrogen into methane. Methane is subsequently expelled through the cow’s front end – through burping – or through the cow’s backdoor – via farting. A cow burps and farts between 160 to 320 litres of methane per day. That is bad news for the environment.
While much of the climate change debate (rightly) focuses on slashing carbon dioxide (CO2) emissions, methane still makes up 16 per cent of global greenhouse gas emissions, according to 2015 figures from the Intergovernmental Panel on Climate Change. Recent research also suggests that methane is 28 times more effective than CO2 at trapping heat.
Two thirds of methane emissions come from human activities: mining, industrial processes, and, crucially, livestock – especially cattle. While one obvious solution to the issue would be to radically reduce our meat and dairy consumption – and hence, the sheer number of cows farting and burping their way through the food industry – some researchers and entrepreneurs have been looking into different methods to tackle the matter.
One way to go about this focuses on the input side – that is, nutrition. A balanced diet and high-quality feed can per se reduce the amount of methane unleashed by bovine orifices. What seems to make a substantive difference, though, is the addition of seaweed to what cows eat.
In 2016, researchers at the James Cook University in Australia mixed a particular strand of algae – called asparagopsis taxiformis – with fluid from cattle rumen in a series of in-vitro experiments. They found that a substance contained in the asparagopsis, the halogenic compound bromoform, had the ability to stifle the methanogens’ action: a two per cent dose of seaweed added to feed seemed to do away with methane altogether, causing minimal disruption to the fermentation – and digestive – process.
More recently, researchers at the University of California, Davis, led by animal science professor Ermias Kebreab, tested the seaweed’s potential on 12 live cows. “We didn't know what [quantity of asparagopsis] to give to the animals, so we started with a quarter of a per cent of the diet,” Kebreab says. “We arrived to one per cent and we had a very good response to the thing. That’s the level where it's quite effective.”
By using a sort of breathalyser for cows, Kebreab’s team found that one per cent of seaweed added to the animals’ daily feed could slash methane emissions by 50 per cent. Luckily, while the cows themselves did not seem to find the algae yummy – that required the concealing the flavour with molasses – the addition of asparagopsis to their diet had no impact on the taste of their milk.
Some questions still remain, though. For one: will asparagopsis’ methane-slashing effect persist in the long run? “We only fed them two weeks: so what happens if you feed them for six months?” Kebreab says. In February, he will kick-start exactly such an experiment, feeding seaweed to 24 beef cattle over six months. The endeavour makes particular sense in California, which recently passed a law requiring farmers to reduce methane emissions 40 per cent by 2030.
Still, a challenge persists: getting enough asparagopsis for all of California’s 2.38 million cows – and, theoretically, for the global cattle population – is not easy. “Right now, there’s no market for that,” Kebreab says.
Stefan Kraan, chief scientist at Ireland-based seaweed product manufacturer Aquaceuticals, says that it all comes down to regulation. Growing seaweed – to the tune of about seven yearly tonnes per hectare of sea – requires governments to issue marine licenses, and Kraan says the application process has often been often too slow.
“For the last ten years, in Ireland at least, nothing moved, it was hard to get licences and to get any activity going,” he says. “But new licenses have been issued in the last two or three months.”
That could change if more governments decided to go down California’s path, and establish more stringent methane emission standards. Already now, some farmers seem to have become more attentive about the subject. “[Seaweed] products are being used primarily for their performance-enhancing aspects, but, at a consumer level, there is more and more awareness of the issue of cattle-related methane production,” says Michael Roe, the commercial director of Agolin, a Swiss company producing feed containing anti-methanogenic seaweed.
Not everyone is convinced that food alone will solve the farting conundrum. Feeding asparagopsis to your cattle every day could be expensive until seaweed production gets up to speed; and we still do not know whether the animals could become inured to the additive, and restart belching methane after a while. That is why other researchers are focusing on the genetic roots of methane emission.
Rainer Roehe, a professor of animal genetics at Scotland’s Rural College, says that genes play a key role in how much methane an animal releases. “There's a large variation in methane production between individual animals,” Rohe says. “We found that this kind of variation in methane production is genetically determined. We can show that the amount of methanogens is determined by the [cow’s] genomics.”
After taking rumen samples from both live animals – which had been previously checked for methane emissions in a “respiration chamber” – and carcasses from abattoirs, Roehe managed to identify 20 genes associated with methane production.
“We can use [genomics] to predict methane emissions of animals without measuring [each cow’s individual] methane [emission],” Rohe says. The plan now is to genetically select cows in order to breed low-emission cattle. According to Roehe, this method could have a tremendous impact: a three per cent reduction in cattle-related methane production every year. “That's a cumulative change.”
In February, Roehe will start collaborating with breeding companies across the UK to select cattle for methane reduction in their farms. Whether you’re team seaweed or team genes, the battle to get rid of cow farts is on.
This article is part of our WIRED on Climate Change series. From the urgent race to make cows fart less to the battle over deep sea mining, we're taking an in depth look at the technologies and ideas at the forefront of our crucial mission to reverse the effects of global warming.
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This article was originally published by WIRED UK
