Scientists have shown that feeding cattle brewer’s grains, a by–product of the beer and ethanol-manufacturing process, can reduce methane emissions by 15 to 20 percent.

The Reducing Emissions from Livestock Research Program, part of the Australian Government’s Climate Change Research Program, looked at practical feeding strategies that farmers can use to curb methane emissions and maintain profitability.

Associate Professor Richard Eckard, Director, Primary Industries Climate Challenges Centre at the University of Melbourne said the project investigated several waste products that were high in oil as feed additives for grazing dairy cattle, including whole cottonseed meal, cold–pressed canola meal, brewers’ grains and hominy meal.

“For every one per cent of oil added to a ruminant’s diet it translates to a three–and–a–half per cent reduction in methane emissions,” Associate Professor Eckard said.

“In the case of whole cottonseed, it not only significantly reduced methane emissions but also increased milk production by 16 per cent, milk fat by 19 per cent and milk protein by 12 per cent.”

The results show that the most valuable time for the oil to be added is when pasture is limited in quantity and has a low nutritional value.

“In spring, our ryegrass gets up to around five per cent oil anyway and you can’t go above seven per cent, so you don’t have as much margin,” Associate Professor Eckard said.

“But in summer, when pasture oil content is around two per cent, adding five per cent oil could reduce emissions by 15–20 per cent. It would also increase milk production due to the slow–release energy provided by oil.”

The study also found that drenching cows with tannin can also reduce methane emissions by up to 29 per cent.

But tannin is very bitter and we had trouble getting cows to eat it voluntarily,” Associate Professor Eckard said.

The project team has also developed a reliable way to measure methane on a larger scale.

“In order to ensure that the various supplements we studied delivered actual methane reductions in a practical sense, we used the open–path FTIR method,” Associate Professor Eckard said.

“This involves measuring methane emissions by shooting beams of light up and down wind of the animals so that measurements can still be taken while the animals are grazing in the herd or flock.”

The project is part of the Reducing Emissions from Livestock Research program – a joint initiative of Meat & Livestock Australia and the Federal Government’s Department of Agriculture, Fisheries and Forestry and is supported by the Victorian DPI, University of Melbourne and Dairy Australia.