Methane Research Programme

The NZAGRC methane programme is jointly planned and funded in partnership with the PGgRc and aligns with existing MPI programmes funded through SLMACC and New Zealand funding in support of the Global Research Alliance on agricultural greenhouse gases. It aims to reduce emissions by directly targeting the methane producing methanogens through the discovery of small molecule inhibitors and vaccines and indirectly through feeding and changes in animal phenotype. 

 

  • Breeding: Research to understand the genetics of host control of ruminant methane emissions, which aims to develop genetic and genomic selection technologies to reduce methane yield and intensity in sheep. The current stage of the programme involves the development and dissemination of practical tools for selection for lowered emissions. A major part of maximising impact and uptake is to explore relative economic value from increased production and potential increased feed utilisation associated with lowered methane
  • Vaccine (jointly supported by PGgRc): A prototype vaccine (which after further development is aimed at producing a vaccine targeted at reducing methane emissions in cattle and sheep by 20%) is being formulated with the help of a commercial partner
  • Inhibitors (previously jointly funded but now fully funded by PGgRc): Research to develop cost-effective inhibitors that reduce methane emissions by at least 20% in sheep and cattle—without reducing productivity—is now being developed, with a view to bring the technology to market
  • Modelling: A tool to help scientists in the NZAGRC/PGgRc programme to develop hypotheses and predict responses in methane formation is in its final stages
Current progress and research stories

The current objectives within the NZAGRC methane programme have made significant progress this year, with the sheep breeding programme getting closer to delivering breeding values to the national flock.

Delving into rumen 'soup': identifying targets to mitigate methane

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What's really in a rumen? It's probably something that most people haven't given much thought to. However, in the search for methods and technologies to mitigate methane produced from ruminant animals, this is a key question.

The rumen of a typical NZ ruminant animal contains a complex ‘soup' of chewed-up plant material, saliva, drinking water, plus a vast array of microbial species. Methane, the potent greenhouse gas, is produced in the rumen by microbes known as methanogens. They use hydrogen, another gas that is produced by other microbes like bacteria that break down ingested feed. By converting hydrogen to methane, the methanogens get the energy they need to grow.

Sandra Kittelmann and Henning Seedorf, along with the rest of the rumen microbiology team at AgResearch, have been delving into the rumen contents of a wide range of NZ sheep and cattle to investigate the microbial communities that live there. By accurately identifying and classifying rumen microbes, and looking for similarities and differences in types and abundances between animals, the search for targets and strategies to reduce agricultural methane is being advanced.

A key outcome of the team's work has been the development of a taxonomic framework to enable classification of the methanogens from the rumen, and from other animal and human intestinal tracts. This work has been recently published in PeerJ (http://dx.doi.org/10.7717/peerj.494). Setting up the framework was a long, and sometimes tedious process, with many of the organisms initially unclassified and most requiring new names. However, the completed classification provides a map that allows researchers to identify the methanogen species that are present in a sample from a rumen. "We may not know what they all do yet", says Sandra, "but we can identify what we've got and what we don't have. Sometimes it's incredibly useful to know what we don't know".

The first use of the new classification was to identify the major methanogens present in NZ ruminants. Surprisingly, regardless of species and diet, there turned out to be a limited diversity of methanogens present. This has big implications for vaccine and inhibitor development. If a new vaccine or inhibitor targets and knocks out the major methanogen groups, it has a high likelihood of working across all NZ species. Currently a Global Rumen Census project (funded by the Global Research Alliance) is underway. Led by Gemma Henderson and Peter Janssen, it aims to survey the diversity of microbes present in rumen samples obtained from a range of locations and farming situations around the world. If the same major methanogens turn out to be globally common to ruminants, any new technologies developed in NZ could be used internationally to help make a real impact on agricultural GHGs.

New taxonomic frameworks for rumen microbes have also been instrumental in a recently published study investigating the microbes present in the rumens of naturally high- and low-methane emitting sheep (http://dx.doi.org/10.1371/journal.pone.0103171). The team were hoping to find differences in the communities present, with the expectation that there was something special about the high-emitters. However, unexpectedly the results showed that it was the low-emitters that had additional, different strains of bacteria present.

After some time spent examining the results of the study, it was deduced that there are actually two types of low-emitting sheep. In the more abundant type, bacteria which don't seem to produce hydrogen have muscled their way into the rumen. Less hydrogen means less methane. The animal breeding team, led by John McEwan, have found that the low-emitting sheep tend to have physically smaller rumens, so current thinking suggests that feed passes through the smaller rumens faster, and the non-hydrogen producing species can establish themselves better under these conditions.

As for the second type of low-emitting sheep (as classified by their rumen microbes), the team are still working on an explanation for this. Sandeep Kumar, a PhD student funded jointly by the NZAGRC in NZ and Teagasc in Ireland, is currently unravelling this issue.

Investigation of rumen samples is a pivotal, underpinning part of the NZAGRC-PGgRc methane programme. With major vaccine and inhibitor trials planned during the next year, understanding the effects that these are having on the methanogens present is very important. So Sandra and her team will continue to receive and study as many rumen samples as they can handle for the foreseeable future, feeding back their valuable results and insights to the rest of the methane team.

Links

http://dx.doi.org/10.7717/peerj.494

http://dx.doi.org/10.1371/journal.pone.0103171


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