Live yeasts enhance fibre degradation in the cow rumen through an increase in plant substrate colonization by fibrolytic bacteria and fungi

AIMS: To monitor the effect of a live yeast additive on feedstuff colonization by targeted fibrolytic micro‐organisms and fibre degradation in the cow rumen. METHODS AND RESULTS: Abundance of adhering fibrolytic bacteria and fungi on feedstuffs incubated in sacco in the cow rumen was quantified by qPCR and neutral detergent fibre (NDF) degradation was measured. Saccharomyces cerevisiae I‐1077 (SC) increased the abundance of fibre‐associated Fibrobacter succinogenes on wheat bran (WB) and that of Ruminococcus flavefaciens on alfalfa hay (AH) and wheat silage (WS). The greatest effect was observed on the abundance of Butyrivibrio fibrisolvens on AH and soya hulls (SH) (P