Feeding seaweed to cows could slash the amount of climate change-inducing methane emissions from their burps.

Preliminary research has indicated a small amount of marine algae added to cattle food can reduce methane emissions from cattle gut microbes by as much as 99 per cent.

Now, scientists in California are hoping to help farmers meet strict new emissions targets by performing the first ever tests of seaweed feed in live dairy cows.

While their early results are yet to be released, team leader Professor Ermias Kebreab at the University of California, Davis, said their initial experiments were “very surprising and promising”.

“Results are not final, but so far we are seeing substantial emission reductions,” he said.

“This could help California’s dairy farmers meet new methane-emission standards and sustainably produce the dairy products we need to feed the world.”

Cow digestion relies on millions of microbes in their guts processing and fermenting high-fibre foods.

This process allows the animals to survive on a diet of grass, but it also produces large quantities of methane – a gas responsible for around a quarter of man-made global warming.

Cattle constantly burp and emit the methane being produced in their stomachs. The gas can also be expelled from their rear ends and from manure, but to a lesser extent.

Science news in pictures Show all 20 1 /20 Science news in pictures Science news in pictures Pluto has 'beating heart' of frozen nitrogen Pluto has a 'beating heart' of frozen nitrogen that is doing strange things to its surface, Nasa has found. The mysterious core seems to be the cause of features on its surface that have fascinated scientists since they were spotted by Nasa's New Horizons mission. "Before New Horizons, everyone thought Pluto was going to be a netball - completely flat, almost no diversity," said Tanguy Bertrand, an astrophysicist and planetary scientist at NASA's Ames Research Center and the lead author on the new study. "But it's completely different. It has a lot of different landscapes and we are trying to understand what's going on there." Getty Science news in pictures Over 400 species discovered this year by Natural History Museum The ancient invertabrate worm-like species rhenopyrgus viviani (pictured) is one of over 400 species previously unknown to science that were discovered by experts at the Natural History Museum this year PA Science news in pictures Jackdaws can identify 'dangerous' humans Jackdaws can identify “dangerous” humans from listening to each other’s warning calls, scientists say. The highly social birds will also remember that person if they come near their nests again, according to researchers from the University of Exeter. In the study, a person unknown to the wild jackdaws approached their nest. At the same time scientists played a recording of a warning call (threatening) or “contact calls” (non-threatening). The next time jackdaws saw this same person, the birds that had previously heard the warning call were defensive and returned to their nests more than twice as quickly on average. Getty Science news in pictures Turtle embryos influence sex by shaking The sex of the turtle is determined by the temperatures at which they are incubated. Warm temperatures favour females. But by wiggling around the egg, embryos can find the “Goldilocks Zone” which means they are able to shield themselves against extreme thermal conditions and produce a balanced sex ratio, according to the new study published in Current Biology journal Ye et al/Current Biology Science news in pictures Elephant poaching rates drop in Africa African elephant poaching rates have dropped by 60 per cent in six years, an international study has found. It is thought the decline could be associated with the ivory trade ban introduced in China in 2017. Reuters Science news in pictures Ancient four-legged whale discovered in Peru Scientists have identified a four-legged creature with webbed feet to be an ancestor of the whale. Fossils unearthed in Peru have led scientists to conclude that the enormous creatures that traverse the planet’s oceans today are descended from small hoofed ancestors that lived in south Asia 50 million years ago A. Gennari Science news in pictures Animal with transient anus discovered A scientist has stumbled upon a creature with a “transient anus” that appears only when it is needed, before vanishing completely. Dr Sidney Tamm of the Marine Biological Laboratory could not initially find any trace of an anus on the species. However, as the animal gets full, a pore opens up to dispose of waste Steven G Johnson Science news in pictures Giant bee spotted Feared extinct, the Wallace's Giant bee has been spotted for the first time in nearly 40 years. An international team of conservationists spotted the bee, that is four times the size of a typical honeybee, on an expedition to a group of Indonesian Islands Clay Bolt Science news in pictures New mammal species found inside crocodile Fossilised bones digested by crocodiles have revealed the existence of three new mammal species that roamed the Cayman Islands 300 years ago. The bones belonged to two large rodent species and a small shrew-like animal New Mexico Museum of Natural History Science news in pictures Fabric that changes according to temperature created Scientists at the University of Maryland have created a fabric that adapts to heat, expanding to allow more heat to escape the body when warm and compacting to retain more heat when cold Faye Levine, University of Maryland Science news in pictures Baby mice tears could be used in pest control A study from the University of Tokyo has found that the tears of baby mice cause female mice to be less interested in the sexual advances of males Getty Science news in pictures Final warning to limit "climate catastrophe" The Intergovernmental Panel on Climate Change has issued a report which projects the impact of a rise in global temperatures of 1.5 degrees Celsius and warns against a higher increase Getty Science news in pictures Nobel prize for evolution chemists The nobel prize for chemistry has been awarded to three chemists working with evolution. Frances Smith is being awarded the prize for her work on directing the evolution of enzymes, while Gregory Winter and George Smith take the prize for their work on phage display of peptides and antibodies Getty/AFP Science news in pictures Nobel prize for laser physicists The nobel prize for physics has been awarded to three physicists working with lasers. Arthur Ashkin (L) was awarded for his "optical tweezers" which use lasers to grab particles, atoms, viruses and other living cells. Donna Strickland and Gérard Mourou were jointly awarded the prize for developing chirped-pulse amplification of lasers Reuters/AP Science news in pictures Discovery of a new species of dinosaur The Ledumahadi Mafube roamed around 200 million years ago in what is now South Africa. Recently discovered by a team of international scientists, it was the largest land animal of its time, weighing 12 tons and standing at 13 feet. In Sesotho, the South African language of the region in which the dinosaur was discovered, its name means "a giant thunderclap at dawn" Viktor Radermacher / SWNS Science news in pictures Birth of a planet Scientists have witnessed the birth of a planet for the first time ever. This spectacular image from the SPHERE instrument on ESO's Very Large Telescope is the first clear image of a planet caught in the very act of formation around the dwarf star PDS 70. The planet stands clearly out, visible as a bright point to the right of the center of the image, which is blacked out by the coronagraph mask used to block the blinding light of the central star. ESO/A. Müller et al Science news in pictures New human organ discovered that was previously missed by scientists Layers long thought to be dense, connective tissue are actually a series of fluid-filled compartments researchers have termed the “interstitium”. These compartments are found beneath the skin, as well as lining the gut, lungs, blood vessels and muscles, and join together to form a network supported by a mesh of strong, flexible proteins Getty Science news in pictures Previously unknown society lived in Amazon rainforest before Europeans arrived, say archaeologists Working in the Brazilian state of Mato Grosso, a team led by archaeologists at the University of Exeter unearthed hundreds of villages hidden in the depths of the rainforest. These excavations included evidence of fortifications and mysterious earthworks called geoglyphs José Iriarte Science news in pictures One in 10 people have traces of cocaine or heroin on fingerprints, study finds More than one in 10 people were found to have traces of class A drugs on their fingers by scientists developing a new fingerprint-based drug test. Using sensitive analysis of the chemical composition of sweat, researchers were able to tell the difference between those who had been directly exposed to heroin and cocaine, and those who had encountered it indirectly. Getty Science news in pictures Nasa releases stunning images of Jupiter's great red spot The storm bigger than the Earth, has been swhirling for 350 years. The image's colours have been enhanced after it was sent back to Earth. Pictures by: Tom Momary

Agriculture is a major contributor to greenhouse gas emissions, and around a third of the emissions from the sector are thought to come from livestock producing methane.

In an attempt to curb this source, California has introduced regulations calling for dairy farmers to cut methane emissions from their 1.7 million cows by 40 per cent over the next decade.

Achieving this goal will require drastic solutions, and Professor Kebreab thinks seaweed could be one of those solutions.

“Since much of a dairy’s methane emissions come from the animal itself, nutrition can play a big role in finding solutions,” he explained.

“The numbers we’re seeing are amazing – well beyond the target that farmers will need to reach.”

In the university’s barns, Professor Kebreab and his team have been testing an algae diet on 12 dairy Holstein cows, and intend to widen their experiments to include more cattle this summer.

To produce feed that the cows enjoy, the researchers cut a small amount of red seaweed with cattle feed and molasses.

Cows are then taken to a device four times a day that measures the amount of methane in their breath as they eat.

The work builds on initial studies carried out in 2015 by a team of Australian researchers that indicated a small amount of seaweed practically eliminated methane emissions from cow gut microbes in lab conditions.

A compound found in some seaweed disrupts enzymes used by the microbes to produce methane.

Lisa Murray's climate change photography Show all 12 1 /12 Lisa Murray's climate change photography Lisa Murray's climate change photography Dinka cattle herders starting their migration in South Sudan Lisa Murray Lisa Murray's climate change photography A Dinka woman fetches water in South Sudan Lisa Murray Lisa Murray's climate change photography Veronica in South Sudan preparing tea outside her home, recently ravaged by heavy flooding Lisa Murray Lisa Murray's climate change photography Children playing in Vietnam. When it floods, transport to and from school is a major challenge Lisa Murray Lisa Murray's climate change photography Sugeng, a fish and crab farmer from Indonesia who suffers financially every time the area floods Lisa Murray Lisa Murray's climate change photography Tan, a vegetable farmer, learning new methods through Oxfam in Vietnam Lisa Murray Lisa Murray's climate change photography Maluk, a 19-year-old from Tonj South, South Sudan Lisa Murray Lisa Murray's climate change photography Normally this farmer in South Sudan would be harvesting sorghum, but rains are late so the hunger season continues Lisa Murray Lisa Murray's climate change photography Herders bringing home their cattle in Afar, Ethiopia Lisa Murray Lisa Murray's climate change photography Farmers harvesting chilli in Ethiopia Lisa Murray Lisa Murray's climate change photography A woman in Tigray, Ethiopia, scares birds away from her crops with a slingshot Lisa Murray Lisa Murray's climate change photography Irula tribe woman in Tamil Nadu Lisa Murray

So dramatic were the results that the scientists thought their instruments must be broken and decided to run the tests again to confirm the 99 per cent drop was real.

While these figures were clearly promising, before new feeds can be rolled out in farms around the world scientists must first rigorously test them in livestock.

Dietary supplements for cows have been known to end in disappointment after showing great promise in the lab – including curry extracts trialled by a team of British scientists that failed when the animals rejected the foodstuff.

“We have much more research to do to determine if seaweed supplements could provide a viable, long-term solution,” said Professor Kebreab.

“But we are very encouraged by these early results.”

Seaweed is an appealing supplement not only because of its gas-limiting effects, but because it is so easy to grow. Seaweed cultivation can be undertaken without land, fresh water or fertiliser.