Tuesday, March 19, 2024

Breakthrough in methane research

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AgResearch scientists and United States researchers have made a major discovery in their work to reduce methane emissions from sheep. They have identified microbial differences in the rumens of sheep with high or low methane emissions. ‘These analyses showed that, although the relative abundance of genes did not differ between the low and high methane groups, the expression of genes involved in the metabolic pathway leading to methane formation were significantly elevated in methanogens within the rumens of high methane-emitting animals.’
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Methane belched from sheep and other ruminants accounts for about 28% of global methane emissions from human-related activities. 

It is produced in the rumen by microbes called methanogens. The work targeting these organisms is aimed at reducing methane emissions from ruminants.

AgResearch scientist and project leader Dr Graeme Attwood, who’s based at AgResearch’s Grasslands campus in Palmerston North, said the results, which have just been published in the top-ranking journal Genome Research, are one of the first major findings of the four-year project.

“The study used the large sequencing and data analysis capabilities of the JGI (the US Department of Energy’s Joint Genome Institute) to look at the occurrence, abundance, and expression of methanogen genes between low and high methane-emitting sheep identified from flocks in New Zealand,” he said.

“These analyses showed that, although the relative abundance of genes did not differ between the low and high methane groups, the expression of genes involved in the metabolic pathway leading to methane formation were significantly elevated in methanogens within the rumens of high methane-emitting animals.”

He says this discovery helps explain the methanogen involvement in this animal trait, and it is likely that further detailed analysis of the large sequence datasets will uncover differences in other rumen microbes which also contribute.

The work is part of a Global Partnerships in Livestock Emissions Research project and has been carried out by the Rumen Microbiology team at AgResearch Grasslands in Palmerston North, and at the US Department of Energy’s JGI facility in San Francisco, California.

The programme aims to breed sheep for NZ farms which are low methane-emitters but also maintain their ability to reproduce and retain or improve their meat and wool production.

The microbial gene expression differences discovered in the study help define the methane trait in sheep and will assist in the selection of future low methane flocks.

“Understanding the microbial composition of a low methane animal and how its rumen works will enable us to focus on targeting the methanogens directly using complementary approaches such as drenches, slow release boluses, or specialised forages and supplements,” Attwood said.

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