Heat map showing the relative abundance (> 0.001 cut-off) and prevalence (75% cut-off) of the prokaryotic genus level OTU groups in the 70 equine fecal samples analyzed. Different detection thresholds are used, providing information regarding the relative abundance of the genus level OTU groups relative to their prevalence. Taxonomic assignments of the genera are given to five taxonomic ranks (phylum, class, order, family and genus) where possible. Where this was not possible, the non-annotated ranks were left empty (e.g. Verrucomicrobia; WCHB1–41; uncultured_bacterium;;; has no information for the family and genus ranks). Genus level groups present in all animals have their taxonomic assignments written in green.