| Abstrakt: |
Simple Summary: Greenhouse gases (GHG) are the major responsible drivers for global warming and climate change. Methane (CH4) is deemed the second most important GHG emitted from anthropogenic sources in terms of global warming potential (GWP) and quantity. Ruminants contribute to approximately one-fourth of all agricultural anthropogenic sources of CH4 emissions. As such, ample time and resources were committed to developing strategies to reduce CH4 emission from ruminants and its negative impacts on the environment. This has led to the development of several techniques for measuring and estimating CH4 emissions from ruminants. This review summarizes state-of-the-art and futuristic technologies for measuring and estimating CH4 emissions from ruminants, and their strengths and limitations, for easy understanding. This review aims to elucidate the contemporary methods of measuring and estimating methane (CH4) emissions from ruminants. Six categories of methods for measuring and estimating CH4 emissions from ruminants are discussed. The widely used methods in most CH4 abatement experiments comprise the gold standard respiration chamber, in vitro incubation, and the sulfur hexafluoride (SF6) techniques. In the spot sampling methods, the paper discusses the sniffer method, the GreenFeed system, the face mask method, and the portable accumulation chamber. The spot sampling relies on the measurement of short-term breath data adequately on spot. The mathematical modeling methods focus on predicting CH4 emissions from ruminants without undertaking extensive and costly experiments. For instance, the Intergovernmental Panel on Climate Change (IPCC) provides default values for regional emission factors and other parameters using three levels of estimation (Tier 1, 2 and 3 levels), with Tier 1 and Tier 3 being the simplest and most complex methods, respectively. The laser technologies include the open-path laser technique and the laser CH4 detector. They use the laser CH4 detector and wireless sensor networks to measure CH4 flux. The micrometeorological methods rely on measurements of meteorological data in line with CH4 concentration. The last category of methods for measuring and estimating CH4 emissions in this paper is the emerging technologies. They include the blood CH4 concentration tracer, infrared thermography, intraruminal telemetry, the eddy covariance (EC) technique, carbon dioxide as a tracer gas, and polytunnel. The emerging technologies are essential for the future development of effective quantification of CH4 emissions from ruminants. In general, adequate knowledge of CH4 emission measurement methods is important for planning, implementing, interpreting, and comparing experimental results. [ABSTRACT FROM AUTHOR] |
