In 2018, there were an estimated 1.002 billion head of cattle worldwide, an increase of 6.5 million head over 2017.¹ Global meat production has continued, and is seemingly continuing, to rise and although cattle now accounts for a relatively smaller percentage of overall meat consumption, there were still over 68 billion tonnes of cattle meat produced in 2014.² Beef exported from the US alone in 2018 was worth 7.3 billion dollars³ so cattle farming remains big and profitable business.

However, there have been growing concerns about the environmental impact of methane gas from cows within cattle farming. Cattle produce a significant amount of methane gas, between 250 – 500 L per day.⁴ Methane is a more efficient and effective heat-trap than CO₂, the most abundant greenhouse gas in the atmosphere, and therefore potentially has a large contribution towards global warming.

As livestock is a key source of nutritional and economical sustenance for many communities, cattle farming is unlikely to disappear in the immediate future. Therefore, finding ways to reduce methane production from cows is an important route to improving the sustainability of cattle farming and minimizing its environmental impact.

Reducing Methane Production

Finding ways to reduce methane production from cows is currently a highly active area of research. Cows, and other ruminant species, produce methane as part of their digestion process. This is because ruminants are one of the few species that can digest cellulose, which is what the cell walls in plants are composed of. Breaking down cellulose is a multi-step process, involving regurgitation and re-ingestion of the food and the use of a large array of microbes that carry out fermentation of the plant material. The fermentation process is what generates the majority of methane gas, which exits the cow via eructation (burping) or flatus (farts).

Much of the research aimed to reduce this methane production involves finding methods to alter the digestive process and microbes in the cow’s stomach. Some success has been found by either changing the composition of the ruminants’ diets, such as increasing the amount of sugarcane feed⁵ or by the introduction of chemicals that act as methane inhibitors.⁶ The challenge with using additives is finding chemical species that are non-toxic and do not have unwanted side effects on produce, be it the meat or milk of the animal.

However, all of this research relies on being able to monitor methane production in cattle accurately and unobtrusively. Indirect calorimetry respiration chambers are often considered to be the ‘gold standard’ of methane measurement methods⁷ but involve large capital investment, are not ideally suited for use with large numbers of animals and require confinement of the animal, which may make such measurements not truly reflective of normal behavior.⁸

As changes in methane emission from dietary changes may be small, sensing technologies need to have good sensitivity as well as reproducibility and accuracy. Recent work has shown that non-dispersive infra-red (NDIR) sensor technologies show greater repeatability for measurement of methane concentrations and that the concentrations measured were in line with those measured by other techniques.⁹ NDIR sensor technologies are particularly effective for methane detection for the same reason it is such an efficient heat trap in the atmosphere, methane strongly absorbs infra-red light.

Gas Sensing

Edinburgh Sensors have thirty years of experience in the development of NDIR gas sensors for the monitoring of hydrocarbons and other gaseous species. Their NDIR devices have already been demonstrating the ability to work well for detecting methane production in cows⁹ in field environments and are designed to be robust, easy to install and use.

The Guardian NG is an example of a Methane monitor that is ideal for such applications, capable of detecting methane in low concentrations of 0 – 1 %.^{10, 11} The Guardian NG has an R323 interface with the option of TCI/IP communications protocol so can be connected to data logging networks to monitor in real-time changes in methane emission levels. The sensor also comes with data logging software, so only requires connection with a cable to a PC to be able to start instantly recording measurements.¹²

The device is designed to be robust, with minimal installation and set-up time. The zero stability is ±2% of range (over 12 months) with an excellent ±2% accuracy. Important for use on live farm environments, the readouts are also temperature, pressure and humidity compensated and will remain accurate over 0 – 95 % humidity conditions.