Measuring methane in the rumen under different production systems as a predictor of methane emissions

Summary

The livestock industries required a technology to rapidly and accurately measure enteric gas emissions from large numbers of individual animals. At the commencement of the project, no such technology existed and there are limitations regarding the application of technologies presently available. A new technology/device would enable researchers and producers to validate methane mitigation strategies in grazing ruminants.

Intra-rumen devices incorporating gas sensors and a wireless sensor network platform have been developed in the project that log concentration of methane, carbon dioxide and hydrogen gas in the rumen for research purposes. The devices are equipped with a novel gas permeable membrane embedded with silver nanoparticles which allows the diffusion of the target gases while blocking corrosive hydrogen sulphide.

Objectives

The objectives of this project were to:

• evaluate the utility of the intra-ruminal device to sense changes in methane, carbon dioxide and hydrogen concentration under varying feeding conditions in ruminants
• determine the ability of the intra-ruminal device to identify high and low methane emitting ruminants that have been previously ranked on respiration chamber measurements
• determine the performance of the intra-ruminal device including analysis of variability, repeatability and verification of total emission of emissions measured
• identification of key issues facing the future development of the device including use under commercial conditions as a device for monitoring and verification of methane emissions from ruminants.

Key findings

The gas-sensing devices have provided the first continuous record of physiological data relating fermentation gases in the rumen and effects of diet and feeding events. This has provided a fundamental basis for understanding the mechanisms which might contribute to a low and high methane phenotype.

In addition, the monitoring of fermentation gases provides an index of rate and extent of fermentation which may assist in identifying animals that have more efficient and productive rumens.

For the device to be able to estimate methane production rate from rumen methane concentration, constant release of a marker gas in the rumen is required. This would enable to device to be used to assess methane abatement methodologies and genetic selection programs.

Benefits to industry

The measurement of temperature and pressure in the rumen by the device could also be used in the future to identify eating, ruminating and grazing behaviour in the animal which may also contribute to differences in productivity particularly in the more extensive and harsh grazing systems of northern Australia.

The gas sensing device could also be deployed for measuring expired gases at a much cheaper cost than current technologies on the market. Therefore the Australian ruminant livestock industries could benefit from the development of this tool in the future for research on enhancing productivity.

MLA action

This project has contributed knowledge on an intra-ruminal methane measurement device. MLA continues to invest in developing methane measurement techniques.

Future research

The current device can be used as a cheap method for measuring expired gases that collect in portable accumulation chambers (PAC) or conventional respiration chambers where flow rate can be measured. The current device has provided a patent platform for the development of an ingestible human gas sensor device and is attracting global interest as the residence time in the gut (24-48 hours) means the current sensors remain stable. The human application appears attractive for further research and development.