Does the altered rumen microbiome of eco-friendlier cows cause more metabolic stress?

Eco-efficient ruminants, which emit less methane and/or show enhanced feed conversion efficiency, harbour a less diverse ruminal microbiome which is particularly enriched with microbes specialized in specific pathways. However, such ecosystem is expected to be less resilient when the environment is altered by (a)biotic stressors. This not only affects the functioning of the microbiome itself, but also might modulate the animal’s health through immune response induction.
Consequently, eco-efficient animals as well as their rumen microbiome are expected to be less resilient, particularly during periods with enhanced environmental and metabolic stress. The transition period, from 3 weeks before to 3 weeks after parturition, is such a period and is the focus period to study the host-microbiome interaction in this project. For this, we rely on inter-animal variability in a large set of host-related parameters, describing eco-efficiency and metabolic stress components as well as a deeply characterized rumen and gut microbiome. To understand the host-microbiome interaction, several candidate key mechanisms are investigated, including systemic or salivary translocation of microbe-associated molecular patterns and enrichment of IgA-coated bacteria.