Measuring livestock greenhouse gas emissions
Laser methane detectors offer a new, fast and accurate way to record methane output of cattle, say's SRUC researcher.
Laser Methane Detectors (LMD) could provide a quick but reliable method of estimating of greenhouse gas emissions (GHG) from livestock an SRUC researcher told a conference this week. Dr Mizeck Chagunda presented his paper ‘Opportunities and challenges in the use of the Laser Methane Detector to monitor enteric methane emissions from ruminants’ at the Greenhouse Gases & Animal Agriculture Conference (GGAA 2013) in Dublin.
The Laser Methane Detector is a hand held portable gas detector that can be pointed at livestock to record their methane output. This device is widely used in the environmental engineering industry to detect methane gas leaks from pipe-lines and landfill sites; however, it was SRUC scientists who first suggested it could be used to measure the amount of methane cattle produce.
Currently it is estimated that livestock farming accounts for about two thirds of all man made methane emissions yet estimates at individual animal level are not available in most production systems.
Dr Chagunda says: “If you look at national inventories of greenhouse gas emissions in a lot of production systems they are either based on small numbers of animals or they are based on a complicated estimation process which cannot access all the required data. This means the estimates have a lot of uncertainty associated with them. The LMD method will allow us to collect data from large numbers of animals without disturbing their normal activities.”
Significantly, work carried out in SRUC, together with collaborators, has found that the LMD method is just as effective at determining higher methane emitting cows from lower methane emitting cows as respiratory chambers. While these chambers are believed to produce the most accurate results they are costly to run; animals have to been brought to the facility and so only small numbers are tested each time. LMDs offer a fast real-time measurement important to production systems and since the device is portable it can be used out in the field. Measuring emissions in the animal’s natural environment is cheaper and could be just as effective.
Researchers found that methane emissions were not constant throughout the day. Dr Chagunda said: “During drinking the cows produced the highest concentration of methane, whereas the lowest concentration of methane was recorded when the cows were idle in the shed.” This may explain the differences in the biological activity of the rumen depending on the activity of the animal.
A downside of the LMD, Dr Chagunda explained, is that the process is time consuming as each cow must individually measured by the researcher. However, the team plan to look into ways of improving the technique.
Dr Chagunda says: “Despite the challenges associated with the use of the LMD, the technique has great potential as an alternative method in measuring livestock methane production.”
