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.
What is the SF6 tracer technique?
How they work
This technique was devised to answer the question ‘How much methane does an animal grazing freely in a field produce over a given period (usually one 24-hour feeding cycle)?’ Sulphur hexafluoride (SF6) is an inert gas that is easy to detect even in minute amounts. In experiments using this technique, a ‘permeation tube’ containing SF6 is inserted into an animal’s rumen via the mouth. This tube will slowly release SF6 over time at a predetermined rate and the released gas will be emitted via the mouth. The animal is fitted with a lightweight ‘yoke’, which carries an air-evacuated canister that slowly draws air at a steady rate from near the animal’s nostrils.
When the animal belches, it releases both SF6 and methane from its nostrils, and some of this is sucked into the canister (along with air surrounding the animal). Canisters are changed daily so that a series of repeat 24 hour measurements can be obtained. The air accumulated
in the canister is analysed later to determine the ratio of SF6 to methane in the sample.
Since the amount of SF6 that is released from the permeation tube over a given period is known, scientists can use the measured ratio of SF6 to methane to calculate how much methane the animal has released over the same period.
Why do it
Measurements are made under realistic conditions and can continue for longer periods of time.
Unlike respiration chambers, there is no easy way to measure exactly what the animals are eating while grazing. Feed intake can be inferred from the animal’s size and weight gain/milk production, or from dung collection, but these are subject to large errors. The SF6 tracer technique is also labour intensive: gas collection canisters are generally changed every 24 hours, for about five to eight days.
Overall, the technique is not as accurate as respiration chambers.
Methane as a greenhouse gas
NZAGRC-PGgRc methane research programme
Guidelines for use of sulphur hexafluoride (SF6) tracer technique (external website)
Back to News