Relationship Between Methane Emissions and Intestinal Methanogenic Microbiota in Micro-Mini Pigs

Methane production in pigs has been less frequently studied in comparison to cattle. In this study, we developed an original greenhouse gas (GHG) monitoring system designed for pigs and explored the relationship between GHG emissions measured using this system and methane-producing archaea in the porcine gut. The system comprises a semi-closed monitoring chamber and a photoacoustic gas monitor capable of real-time gas concentration monitoring. A gut microbiota analysis was conducted in parallel with the GHG measurements. Microbiota analysis revealed that the genus Methanobrevibacter dominated the intestinal microbiota of micro-mini pigs, followed by the family Methanomethylophilaceae and genus Methanosphaera. Analysis of GHG emissions indicated that carbon dioxide emissions were correlated with body weight, while methane production was not associated with body weight, but rather with the abundance of the genus Methanobrevibacter in the gut. Methane production in the lower gastrointestinal tract of pigs was thought to be positively correlated with dietary fiber intake, and the composition of the intestinal microbiota may also play a role in methane generation. These findings will contribute to advancing research on GHG emission reductions in livestock production. However, a more comprehensive understanding of archaeal diversity requires further detailed analyses using methods targeted specifically at archaea.