Australian Trial of Seaweed Cow Feed Fails To Achieve Hoped-For Methane Cuts

An anonymous reader quotes a report from The Guardian: One of the world's longest commercial trials of a seaweed supplement that the global meat industry hopes could slash methane from beef cattle has recorded much lower reductions in the potent greenhouse gas than previous studies. Putting the supplement into the diets of 40 wagyu cattle in an Australian feedlot for 300 days cut the methane they produced by 28%. The supplement was derived from the red seaweed species Asparagopsis, which has been widely promoted as being able to cut methane by more than 80%, with some experiments suggesting reductions as high as 96%. Globally, the UN's Food and Agriculture Organization estimates, methane from burping cattle -- known as enteric emissions -- releases about 2.1 billion tons of CO2-equivalent a year, compared with the 37.5 billion tons of CO2 from burning fossil fuels. But because methane is about 80 times more potent than CO2 at warming the planet over a 20-year period, cutting methane is seen as a way to slow global heating faster. The trial, reported by the red meat industry's marketing and research group Meat and Livestock Australia (MLA), also found animals given the supplement ate less food and weighed 15kg less by the time they were sent for slaughter. Dr Fran Cowley, a livestock scientist at the University of New England who led the trial, said it was the longest run so far using the red seaweed. She said more research was needed to understand why the wagyu in the trial had not delivered the same level of emissions reductions as other experiments. One factor could be the way the methane was measured in the trial, which used an open-air system in a feedlot compared with animals measured in dedicated indoor chambers. But the trial report noted that other experiments over shorter timeframes using the same open-air measurement technique had recorded higher methane reductions. The seaweed was freeze-dried, mixed in canola oil and added to the animals' feed. In this trial it was given to the animals at slightly lower concentrations than other experiments that showed much higher methane reductions. Cowley said it was also not clear why the animals on the supplement ate less food and put on weight more slowly. Accounting for the extra 35 days the animals would have taken to reach the same weight would have theoretically meant the emissions savings were cut from 28% to 19% as they would have been alive for longer, all the time emitting methane. The study also found that the seaweed supplement had no effect on the wagyu's flavor or other properties.

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