Long-term effects of Mootral on rumen bacteria and archaea

Due to its negative effect on the climate it is desirable to mitigate methane emissions by ruminants. The rumen contains a complex community of microorganisms of which Archaea are capable to produce methane from various substrates. Methane reduction can either be achieved by directly altering rumen Archaea or by altered substrate supply for methanogenesis. Here we observed the long-term effects of a plant-based product on ruminal fermentation, gas production and the archaeal and bacterial community in an in vitro model. The garlic-citrus based product induced a clear reduction in methane production and a shift in the short chain fatty acid pattern, however, this effect was transient. The number of methanogenic Archaea was reduced and the Archaea community composition was shifted towards Thermoplasmatales, while the bacterial community was barely affected. Moreover, alterations of the metabolome were observed.