Portable Accumulation Chambers (PAC) for Measuring Enteric Methane in Cattle

Breeding has been shown to be a viable solution for reducing methane emissions in ruminants but requires obtaining on-farm measurements of methane. One technology that has successfully been used on-farm to obtain short-term commercial methane measurements in sheep and goats is portable accumulation chambers (PAC). However, the original PAC units are unsuitable for cattle. In this project, PAC units designed and engineered specifically for cattle were developed and used to measure methane and carbon dioxide emissions from 125 Angus-Hereford (pure or crossbred) heifers across two time-periods. PAC performed as expected with no animal behaviour problems and were shown to be a suitable high-throughput method for the measurement of methane emissions from young beef cattle. The repeatability was found to be 0.35 ± 0.08 for methane emissions (g/day) (CH4), 0.13 ± 0.09 for carbon dioxide emissions (g/day) (CO2), and 0.31 ± 0.09 for the molar ratio trait of CH4/(CH4 + CO2). These results suggest that the newly designed cattle PAC units could enable large-scale on-farm methane measurements to be collected for the purpose of ranking animals on their methane emissions. This would facilitate the development of breeding schemes to select for low methane emitting cattle. Future studies should be conducted to investigate the heritability of PAC traits obtained from the cattle chambers.