Livestock is a significant contributor to greenhouse gases. The ruminant digestive system creates ample amounts of methane which is released into the atmosphere. It is difficult to measure the amount of methane produced by cows because unlike emission stacks, ruminant exhaust cannot be controlled or monitored. However, researchers from the University of Bristol and the Teagasc Animal and Grassland Research Centre in Ireland have made the connection between methane production and a certain chemical found in the stool of cows, sheep, and other animals. This link may be used to more accurately estimate methane emissions by animals and assess their contribution to global warming.
Livestock is a significant contributor to greenhouse gases. The ruminant digestive system creates ample amounts of methane which is released into the atmosphere. It is difficult to measure the amount of methane produced by cows because unlike emission stacks, ruminant exhaust cannot be controlled or monitored. However, researchers from the University of Bristol and the Teagasc Animal and Grassland Research Centre in Ireland have made the connection between methane production and a certain chemical found in the stool of cows, sheep, and other animals. This link may be used to more accurately estimate methane emissions by animals and assess their contribution to global warming.
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Through various methods, people are able to calculate the emissions they produce from generators, turbines, boilers, and furnaces. Many governments demand an annual statement of emissions by every company with a regulated system. Some companies have to install continuous emissions monitors which constantly measure what comes out of the stack. But livestock operators have been exempt from such rules even though their animals produce methane, a potent greenhouse gas.
"We're quite good at measuring man-made CO2 emissions, but techniques to measure the animal production of methane – a much more potent greenhouse gas – have serious limitations," stated co-author, Dr. Fiona Gill, postdoctoral researcher at Bristol who is now at the University of Leeds. "If we can identify a simple biomarker for methane production in animal stools, then we can use this along with information on diet and animal population numbers to estimate their total contribution to global methane levels."
The chemical found in stool is called archaea, which are symbiotic microbes living in the foregut of ruminant animals. The product of their metabolism is methane which is expelled from the body through burping or flatulence. The microbe was initially found inside the animals guts, and the research expanded to locate it in the feces. The scientists then compared the microbe concentrations in feces of animals which were on different diets.
Principal investigator, Dr. Ian Bull said, "Two groups of cows were fed on different diets and then their methane production and faecal archaeol concentration were measured. The animals that were allowed to graze on as much silage as they wanted emitted significantly more methane and produced faeces with higher concentrations of archaeol than those given a fixed amount of silage, supplemented by concentrate feed. This confirms that manipulating the diet of domestic livestock could also be an important way of controlling methane gas emissions."
Ruminants are thought to produce about one fifth of all methane gas worldwide. In the past, researchers had tried to measure methane production directly from the animals using respiration chambers, but this proved to be too cumbersome for the researchers and the animals. This research is significant for more accurately measuring greenhouse gas production.
The article is published in the journal Animal Feed Science and Technology.
For more information: http://www.elsevier.com/wps/find/journaldescription.cws_home/503299/description#description/article/S0377-8401%2811%2900125-8/pdf
