Measurement of methane production rate in the rumen using isotopic tracers

Abstract

Methane production by ruminants has been estimated by isotope dilution (10) using both 3H-and 14C-labelled CH4. As with any technique of this type, its accuracy depends on the efficient mixing of the labelled material (tracer) within the pool that is to be measured (tracee), in this case CH4 in the rumen. The solubility of CH4 is low and its diffusibility is high, so these properties cause difficulties not encountered with non-gaseous solutes. However, with care these problems can be minimized, and the continuous infusion of 14CH4 into the rumen can yield valuable measurements of methane production. The technique can be used to estimate production in the rumen by sampling the gas phase in the dorsal rumen, or alternatively total tract CH4 production (less a small correction for methane lost from the anus) if total expired gases are collected. © 2007 IAEA.