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Practical Monitoring of Enteric Production from Individual Ruminants

出版	Wageningen University, 2024
ISBN	946447954X9789464479546
URL	http://books.google.com.hk/books?id=ANyM0AEACAAJ&hl=&source=gbs_api

註釋A first practical monitoring device is introduced in Chapter 2. This portable accumulation chamber (PAC) is used for small ruminants (e.g. sheep, goats). The methane and carbon dioxide produced by the animal accumulates in the chamber before being sampled and the methane production rate (MPR) determined from the measured increase in concentration and air volume. Literature research showed that this device is already used around the world, but its performance in terms of absolute measurement accuracy has not been tested. Using a mass flow controller (MFC) releasing known masses of methane, we investigated the ability of a set of ten PAC to measure absolute methane production levels, and to rank animals according to them. This study showed that the measurements made by the PAC were highly repeatable across chambers and replicates. However, methane recovery appeared to be under-performing by roughly 30%, and to be significantly decreasing with increasing injected mass. We suspect both the under-recovery and the drift to be due to measurement errors made by the gas analyser as it was not calibrated. The results of this study emphasize the necessity of whole-system calibrations when monitoring gaseous exchanges. We could conclude that the tested set of PAC can be used to rank animals based on their MPR but should not yet be used for studies requiring high measurement accuracy.