Courtesy CIFOR
It’s a fact that cows are bad for the environment. They constantly parp and belch out a range of greenhouse gases as they munch on grass, and contributed the equivalent of a staggering 6,000 million tonnes of CO2 to the atmosphere over the course of 2013. But scientists in the US have discovered that a seaweed diet can help reduce bovine flatulence by a significant degree. By Jeremy Torr.
California, April 2021. Cattle produce some 11% of all greenhouse gas (GHG) emissions. That’s because they are ruminant animals. They are called that because they have four separate stomach compartments, with the biggest one called the rumen. This is where the cow ferments the grass it eats, so it is more easily digestible in the other stomachs. As microbes break the grass down, carbon dioxide and hydrogen are produced as byproducts – and if you can imagine a stomach full of CO2 hydrogen, it is as uncomfortable as it sounds. In fact it can get to poisonous levels.
So cows have developed their own special stomach bacteria called methanogens, which live in the rumen. They convert the excess CO2 and hydrogen into less toxic methane – which is then burped out of the cow’s mouth.
Unfortunately for the planet, methane is some 30 times more dangerous as a GHG than CO2. In grassy Ireland, for example, methane accounts for nearly 58% of agricultural emissions and almost 20% of total national emissions. Cows are a menace to our climate.
“I love milk” - UCD professor Ermias Kebreab. Courtesy UCD
So scientists all over the world are looking at ways to reduce bovine GHG, and at University of California, Davis (UCD) they think they have discovered an answer.
“Seaweed may be the super food dairy cattle need to reduce the amount of methane they burp into the atmosphere,” it claims in a recent report. “Early results from research indicate that just a touch of ocean algae in cattle feed could dramatically cut greenhouse (bovine) gas emissions.”
The special algae in this case is found in seaweed called Asparagopsis taxiformis that can significantly cut down GHG emissions from cows.
“Since much of a dairy’s methane emissions come from the animal itself, nutrition can play a big role in finding solutions,” said UCD animal science professor Ermias Kebreab.
Kebreab is running an experiment on the feed of 12 Holstein cows, and has discovered that adding 2% by weight of A. taxiformis to their diet helped reduce methane emissions by over 80%. “Results are not final, but so far we are seeing substantial emission reductions (with the new feed),” said Kebreab. “This is a very surprising and promising development.”
The team hypothesise that seaweed apparently inhibits an enzyme that contributes to methane production, and when a small proportion of molasses is also added to the feed, another problem – stinky cow poo – is also removed. “The molasses masks the smell,” Kebreab says, “and they enjoy their feed.”
Asparagopsis taxiformis works magic in a cow’s stomach. Courtesy UCD.
Previous experiments on cattle feed have worked in the lab, but not on the farm, says Kebreab. But the UCD team used the seaweed feed to nourish 12 live cows in three groups. Two groups were fed with different doses of seaweed, and one group was a control (no seaweed) group. The cows’ methane output was measured as they grazed, four times a day.
“The numbers we saw were amazing,” said Kebreab, “well beyond the target that farmers will need to reach.” The cows’ milk was also tested for things like yield, flavour and nutritional content, and it was noted that the milk the cows produced was as good and safe as that from the control group. Work is now ongoing to discover if the changed diet will affect the taste of meat on beef cattle raised on the new diet.
The researchers noted that he most important aspect of the trial was that “… the use of A. taxiformis impacts DMI - (dry matter intake) not ADG (average daily weight gain), therefore increasing overall feed efficiency in growing beef steers.’
This means the use of Asparagopsis taxiformis shows its potential to reduce the cost of production as well as offer significantly reduced GHG emissions. “This has the potential to transform beef production into a more economically and environmentally sustainable red meat industry,” said the researchers.
Next steps for the use of Asparagopsis as a feed-additive will be to develop aquaculture techniques for growing the seaweed, as well as processing techniques and the economics of the supply chain. But the potential is massive.
Sustainable dairy production is not just an academic issue for Kebreab. He loves milk.
“Since I was a young boy growing up in Eritrea in the Horn of Africa, I was amazed how an animal that eats just grass could produce such a high-quality food,” he said. “And I loved the taste. We didn’t get that much — maybe once or twice a week. I always wondered, can we find a way to produce enough milk for everyone?”
So if seaweed proves to be a climate-smart supplement, producing more milk could be environmentally friendly, too. As Kebreab notes, “Growing seaweed doesn’t require land, fresh water or fertiliser.”