Contemporary Methods of Measuring and Estimating Methane Emission from Ruminants

Abstract

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.

Global Warming and Dairy Cattle: How to Control and Reduce Methane Emission

“…Ruminant livestock is expected to emit between 80 and 95 million tonnes of CH 4 per year globally [ 29 , 30 , 31 ]. CH 4 generation also represents a loss of energy availability to the host ruminant animal, often accounting for between 2% and 12% of total energy availability [ 25 ]. Cattle and sheep production systems contribute the most to GHG emissions in agriculture, accounting for up to 18% of total global GHG emissions, mostly in the form of enteric methane [ 32 ].…”

“…As indicated by frequent reviews, a wide spectrum of technologies ( Table 1 ) is being developed and used to quantify methane emissions by individual dairy cattle under varied environmental conditions [ 10 , 25 , 42 ]. All approaches have various application scopes, benefits, and drawbacks, and none are excellent [ 9 ].…”

“…It is necessary to take breath measurements since 99 percent of methane is expelled through the mouth and nose, whereas just 1 percent is emitted through the anus [ 10 , 46 ]. Portable and noninvasive methods that do not disrupt the cow’s daily routine or environment are particularly interesting [ 9 , 25 ].…”

“…There is a need to perform more studies to find the most effective food supplement or its composition and contribute to reducing methane emissions without compromising animal health and production. This demands the use of low-cost and portable technologies for estimating CH 4 emissions on a wide scale while combining it with trustworthy forage [ 25 , 26 ].…”

Quantification of methane emitted by ruminants: a review of methods

“…Therefore, it becomes imperative that the chosen quantification methodology is appropriate to the measurement purpose and provides sufficient evidence to support further investigation or recommendation without leaving much space for speculation or error, which creates distrust in science. Other publications have discussed existing techniques and methods to measure and estimate GHG emissions of ruminants ( Cole et al, 2018 ; Bekele et al, 2022 ).…”