Methane emissions from Australian cattle are 24% lower than previously estimated - and that is very substantial, given the overall percentage of animal methane in the total greenhouse gases in Australia, according to data based on eight years of research into ways to reduce emissions in livestock. The new method has been published in the journal Animal Production Science and resulted in an update of the National Greenhouse Gas Inventory (NGGI).
CSIRO’s Ed Charmley said the work was conducted because of concerns about the large differential between NGGI and Intergovernmental Panel on Climate Change (IPCC) methane emission figures for Australian cattle, as well as doubt surrounding the accuracy of previous calculation methodologies used for cattle — particularly northern Australian cattle, where it was assumed pasture quality was very poor, leading to high methane emissions. “Different methods used to calculate emissions from livestock in temperate and tropical regions were based on studies done in the 1960s and 1990s, mainly with dairy cattle,” Dr Charmley said. “Both of these past methods were found to be likely overestimating the emissions from cattle.”
The revised method is based on improved ways of estimating ruminant methane emissions from forage-fed beef and dairy cattle, and has been tested against international defaults provided by the IPCC. The method has also brought the NGGI in line with the estimates of the IPCC, much to the delight of Meat & Livestock Australia (MLA).
“This revelation clearly shows livestock-based emissions are nowhere near what they were thought to be and will help improve the accuracy of Australia’s national greenhouse gas emissions estimates,” said MLA General Manager, On-farm Innovation Dr Matthew McDonagh. “This is positive news for the Australian livestock sector as it seeks to continually improve its production efficiencies and demonstrate its environmental credentials.”
MLA Manager, Sustainable Feedbase Tom Davison added that the latest research findings from the National Livestock Methane Program (NLMP) show there are a number of simple management measures producers can implement to substantially reduce methane emissions while increasing productivity. “Some of these are as simple as integrating leucaena into grazing systems, improving growth rates or herd reproductive performance, while other future techniques may include feeding red-algae to livestock and have been prioritised for further research,” Dr Davison said. “We look forward to continuing to make further gains in this field for the mutual benefit of both our livestock industries and environmental sustainability.”
Generally if higher quality leguminous feeds are a larger part of the diet, then methane emissions per beast falls. Over the past 20 years or so, grass fed pasture diets have replaced the push to improve forage with legumes, more common in the 1970s - 1980s. A swing back to a higher legume % based diets in the paddocks is emerging and methane emissions may continue to fall, as well as the higher quality feed also helping with animal productivity generally.
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