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Methane-busting seaweed for cows

In this section, you’ll go on a journey of scientific discovery to reduce the methane emissions from cows using an unlikely hero, seaweed. Hi, I’m Professor Nick Paul. I’m a marine scientists from the seaweed research group at the University of the Sunshine Coast in Australia. Did you know that methane is a much more potent greenhouse gas than carbon dioxide? Over the short term, the next 10 years or so, it causes 80 times more heating than CO2. This is why there was the global methane pledge at the latest COP 26 meeting of countries signing up to a 30% reduction in methane by 2030. This is crucial if global heating is to stay at one and a half degrees.
methane emissions come from a few different sources, from fossil fuel extraction from landfill and from agriculture. So that’s cropping especially rice, and also from ruminant animals. All ruminants, that’s cattle, sheep, goats, and giraffes emit methane as a byproduct of digestion. Just to be clear, that’s 95% at the front end through constant burping. The scale of these emissions is substantial. Just on cows there are 1 billion so that’s a 1000 million head of cattle on the planet. In Australia, for example, there are 25 million cattle including beef and dairy cows. Most cattle are out on pasture grazing on grass, but about a 10th of these are regularly fed a mixed feed ration.
Researchers are already working on finding the best novel feed ingredients and seaweed has come out on top as one of the most exciting options. Now it’s not just any seaweed. There are more than 10,000 varieties around the world. But there is only one special type out of all these different seaweeds large and small green, red and brown. There’s a pink seaweed called Asparagopsis. Our original work found that it has a huge impact. Almost all the methane could be reduced with a tiny sprinkle of dried seaweed mixed into the cow diet less than a handful a day. So what’s so special about this seaweed? Well, I’m a little biassed, as I have been studying this seaweed since I was an undergrad.
But it is remarkable that when you look under the microscope, you can see these dark brown gland cells where they store the active ingredients. So in nature, seaweed use these compounds to manage the microbes on their surface. Who would have thought that the same ingredient could also be used to reduce methane in cow burps. The methane effect was so astonishing that we had to rerun the trials to be sure. We confirmed the results and since then, others have repeated the findings all over the world. We knew that cattle around our coasts occasionally graze on washed up kelp. But this was something altogether different.
Because it was such a novel result, we were able to publish the findings as a patent as a means to drive investment in this new technology. Now, if you’re thinking that all of this is too good to be true, why aren’t they doing this already, it’s important to highlight there’s still a way to go before seaweed becomes a mainstream part of the global methane pledge. There are two key things that need to be addressed. We need to find an environmentally sustainable source and we need to make it financially viable for a farmer to use. So firstly, because there are just so many cows, seaweed cannot be wild collected.
It has to be farmed, and this farming needs to be done at a scale never before seen all over the world using locally sourced seaweed. Right now we’re in the United Nations decade of ocean science for sustainable development. So we need to create policies for seaweed farms of the future that ensure environmental and social sustainability. Secondly, we need to make sure the enterprise is economically sustainable by driving down the cost of farm seaweed. And by demonstrating the benefits of the seaweed to the farmers. So these benefits don’t just stop at methane reduction. By feeding the cows seaweed, they’re able to convert that lost energy into production.
Not only that, we recently found that the same pink seaweed boosts the immune system of animals and increases the growth rates of fish. So taking this more holistic view of seaweed farming by making sure it is both environmentally and socially sustainable, and by finding new applications for natural ingredients in agriculture and aquaculture, we will help drive the uptake of this exciting new application. Both will be keeping researchers business and governments busy for the next decade. It’s an exciting time for seaweed science.
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Life Below Water: Conservation, Current Issues, Possible Solutions

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