CHANGSHA, Dec. 25 (Xinhua) -- Can monitoring burps help fight climate change? Chinese zoologists have recently developed a system that estimates methane emissions from cattle and sheep by tracking their burp behavior, offering an innovative tool to support China's emission reduction efforts in agriculture.
The methane emission monitoring equipment, developed by researcher Tan Zhiliang's team from the Institute of Subtropical Agriculture (ISA) under the Chinese Academy of Sciences, was unveiled in Changsha in central China. According to Science and Technology Daily report, the device can show the burp spectrum of cattle and sheep, and calculate the animals' daily methane emissions based on the spectrum.
METHANE EMISSIONS
Livestock farming is one of the major sources of greenhouse gas emissions in China's agriculture sector, with methane produced during the digestion of ruminants like cattle and sheep accounting for 66 percent of agricultural methane emissions.
Accurately measuring the methane produced by cattle and sheep burps is key to agricultural emission reduction. However, China has long lacked high-precision, low-cost, safe and reliable methane emission monitoring equipment suitable for on-site use in pastures.
To address the challenges in monitoring regional carbon sources and quantifying carbon budgets for climate change response, the Chinese Academy of Sciences launched strategic priority research programs at the end of 2010. The ISA team carried out the research project on livestock methane emission reduction.
At the start of the research, the primary method used was the respiratory metabolic chamber, which monitors total enteric methane emissions from cattle and sheep. This required confining animals in a sealed chamber for continuous monitoring over 48 hours. While data could be obtained, the efficiency was extremely low, and it also severely impacted the animals' feed intake and welfare.
The team discovered that 90 to 95 percent of the methane released by cattle comes from the mouth, primarily through burping, while the remaining 5 to 10 percent is released as flatulence. For this reason, they chose burping as the focus of the new system.
NEW METHOD
The shift to monitoring burp was key to the breakthrough. But how could methane emitted from the mouth be measured accurately? The sulfur hexafluoride (SF6) method used at the time required prolonged continuous monitoring, produced highly variable results, and involved SF6, a potent greenhouse gas.
Through extensive data analysis, the team found that continuous 24-hour monitoring was unnecessary. Methane emissions for an entire day could be accurately estimated by observing just a few key periods.
Wang Min, lead researcher, said that cattle and sheep burp about every 60 to 70 seconds with no obvious movement. People might think they are just idling, but they are actually burping and emitting methane.
"By analyzing large-scale daily methane emission data, we identified eight key time periods for collecting gas samples, allowing us to accurately assess full-day emissions," explained another lead researcher, Wang Rong.
Previously, measuring one animal using a respiration chamber took two days, while measuring 30 animals would take two months. The new method can measure 30 animals in less than a week with minimal impact, producing results that differ from continuous monitoring by only 1.5 percent.
WIDE APPLICATION
Analysis of monitoring data by the new system from over 20 provincial regions across China found that the methane emission intensity published by the Intergovernmental Panel on Climate Change (IPCC) overestimates China's actual emissions.
"Taking dairy cows as an example, modern cows produce more milk than before, but the amount of methane emitted per kilogram of milk produced has decreased. This indicates China's continuously improving livestock farming technology," Wang Rong said.
Based on this system, the team also developed methane-inhibiting feed additives that are safe for animals. Adding the inhibitors to feed can reduce methane emissions from cattle and sheep by 20 to 30 percent.
The system has been deployed and applied in over 20 universities and research institutes, as well as more than 50 farming enterprises across 23 provincial regions in China, initially establishing a methane monitoring network that covers major livestock regions.
Wang Min noted that the team plans to integrate technologies like AI visual recognition, autonomous cruising, and the Internet of Things to develop methane monitoring robots for unmanned operation.
Farmers would only need to set a monitoring plan. The robots could then automatically identify cattle and sheep, plan routes autonomously, and complete monitoring tasks, with data uploaded to the cloud in real time, requiring no manual intervention at all.
In the future, the team plans to develop additional equipment to provide essential data for breeding low-emission livestock, creating emission-reducing feeds, and calculating farm carbon footprints. ■
