Ruminating on seaweed

Could feeding cows and sheep with additives like seaweed or garlic cut the livestock industry’s greenhouse gas emissions? David Jesudason finds out.

There are numerous reasons why greenhouse gases are increasing and accelerating global warming. Deforestation in Brazil and Indonesia produces more emissions than the world’s cars, while the burning of fossil fuels by giant oil and gas firms accounts for one third of global emissions.

Around 14 per cent of global greenhouse gas emissions can be attributed to agriculture, according to the Food and Agriculture Organization, with roughly 40 per cent of those emissions coming from methane released by cattle (although estimates do vary).

So recent news saying scientists have discovered that methane emissions can be reduced by feeding cows seaweed, which reduces the methane emitted by their farts and burps, offers a ray of hope. Initial studies found that adding a small amount of seaweed, which contains a compound called bromoform, to the livestock’s overall feed disrupted the enzymes that produce methane in the cow’s gut.

However, one study revealed a more conflicting picture. Not only would producing enough seaweed for the world’s 1.5 billion cattle be impossible, research found, but the cows’ guts (microbiomes) seemed to adapt and reduce the effectiveness of a seaweed additive.

Scientists were, however, impressed by the initial results and, despite the need for further research, trials have begun on livestock in the US, Australia and New Zealand.

Dr Gordon McDougall, senior research scientist of environmental and biochemical sciences at the James Hutton Institute, in Dundee, is not yet at the stage to feed any seaweed to cattle but has conducted tests on a “staggering” amount of varieties on the Scottish coast. He says that seaweed may have other ecological advantages if fed to sheep or cows.

Gordon McDougall seaweed research additive livestock
Feeding seaweed to ruminants could substitute soya as protein in animal feed and reduce ruminants’ methane emissions.

“[Reducing methane] is definitely something we are interested in, but at the moment it’s not our prime consideration,” he says. “One of the first things we are interested in is protein content. It’s relatively well known that various seaweeds have a relatively high content of protein. Therefore, one of the ideas we were toying with was the idea that you could include up to a certain level in animal feed and then reduce the amount of things like soya bean.”

This means instead of shipping in soya from places like Brazil, where the crop contributes to deforestation, food additives like seaweed could be grown locally, reducing the carbon footprint and reinvigorating local industry.

“Also, there’s a supply issue,” McDougall adds. “[If farmers] are dependent on obtaining the soya bean from somewhere like Brazil and if that supply was turned off then they’re in trouble finding something with that protein level.”

Sheep seaweed ruminants emit methane
Ruminants such as sheep and cows emit methane, a potent greenhouse gas.

Replacing an imported feed with a local ingredient would impress Orcadian cattle farmer Steven Sanderson, who gives a little soya annually to his cows when they are pregnant, which makes their colostrum richer and improves their calves’ health.

“It gives the calves a better start in life.” he says. “I’m surrounded by seaweed and if the product was there, I’ll be happy to pay for it.”

Dr Katerina Theodoridou, lecturer in farm animal nutrition at the Institute for Global Food Security which is part of Queen’s University Belfast, and her colleague Mairead Campbell, are also in the lab stage of testing seaweed as an additive. They have found evidence that there is a high reduction in methane in lab tests, and also agree that replacing soya as a protein is a key concern.

“The other problem nowadays with ruminant feeding is protein is poorly utilised by ruminants,” says Theodoridou. “The animals are not receiving all the protein that is needed. And if we have protein waste, we have a lot of ammonia waste in the faeces or urine of the animal which is bad for the environment.”

Reducing ammonia pollution through giving seaweed as an additive could have far-reaching consequences for the livestock industry, but Theodoridou points out that the research is still at the rudimentary stage.

“The reason seaweed has the potential to reduce ammonia and methane emissions is because in seaweed there are bioactive compounds called phlorotannins,” she adds. “These compounds have different mechanisms by which they can reduce methane and ammonia. And this is why we would like to investigate it further.”

Cows fed with Mootral
Cows on Brades Farm, Lancashire, have been fed with an additive made of citrus and garlic. 

Seaweed might also not be the only additive that can reduce carbon emissions. There is a new trial looking at how charcoal (or biochar) can reduce methane emissions, while another additive that is already on the market has yielded results for a UK farmer: Mootral.

Joe Towers, of Brades Farm, runs a family dairy firm in the Lune Valley in Lancashire, which milks 380 cows a day on 400 acres, supplying discerning baristas interested in high protein milk. After seeing the first headlines about seaweed research in 2017, he applied for a Nuffield scholarship and began working with biotech firm Mootral. Instead of seaweed, Mootral is a mix of garlic and citrus, which when added to Towers’ cattle feed reduced his cows’ methane emissions over a period of time.

“Science has been pursuing a food additive to reduce methane for decades now,” says Towers. “The perennial issue is that you get this short-term effect and the microbiome of the cow adapts and responds and, therefore, the impact tails off. Mootral seems to have overcome that problem.

“It was fed on our farm for a three-month period with testing done throughout that period and there was not a tail-off, and that is consistent with the research farms used prior to our farm,” he says, adding that the additive has had further advantages in discouraging flies during hot weather.

In the UK, the National Farmer’s Union (NFU)’s pledge to reach net zero emissions by 2040 includes a range of techniques including precision application of fertilisers, as well as feed additives.

It’s the start of the journey, but research into feeding ruminants with seaweed, charcoal or garlic could help farmers cut their emissions, improve animal health and have far-reaching consequences for the global livestock industry.


Leave a Reply

  1. Interesting article, but how does the consumption of seaweed, garlic and biochar affect humans as part of their diet? Some few years ago various seaweeds were sold by health food shops for human consumption (it’s big in Japan apparently) I tried some, nicer than some other vegetables in a lot of cases, but fairly expensive (it did come a long way). I can’t remember the effects on me as far as methane goes but I’d be willing to give it another go – purely in the cause of science (lol) especially if a local source could be found in the local area – how about Laver (?) Bread in Wales?

    Additionally I consume a fair amount of garlic which I find is very enjoyable but as to the effects of methane, it doesn’t seem to have much use with me! As for biochar, funnily enough I don’t fancy a nice piece of charred tree for lunch . . . . . but I’d give her a go. This is the sort of thing that to my mind science is about – not flying to the moon or anywhere else for that matter. Lets fill people bellies first before we start going off world etc can we – to those who are working on this type of science I’ll say good for you keep it up! Enough for now methinks……

    the Walrus

    1. Laver bread is an amazing mineral rich food which provides high quantities of calcium, iron, potassium, magnesium and iodine and vitamins A ,B, B2, C & D.- definitely worth putting on the menu as a UK ‘superfood’ for that reason alone!


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