Differences in the microbial community abundances of dairy cattle divergent for milk urea nitrogen and their potential implications

The first objective of this experiment was to determine and describe any differences in rumen microbiota relative abundances between dairy cattle divergent for MUN breeding values (MUNBV). The second objective was to ascertain whether any differences in rumen microbiota relative abundances may be associated with phenotypical differences already observed in dairy cattle divergent for MUNBV. Rumen microbiota data were collected and collated from multiple trials that had been conducted investigating differences in dairy cattle divergent for MUNBV where rumen samples were taken via esophageal intubation. On average 8% of the rumen microbiota genera detected differed in their relative abundance based on MUNBV. High-MUNBV dairy cattle had a 10% increase in the relative abundance ofBasfia and a 20% increase in the relative abundance ofSuccinivibrio compared with low-MUNBV dairy cattle. BothBasfia andSuccinivibrio have potential implications for rumen fermentation that require further investigation. High-MUNBV dairy cattle also had a 17% increase in the relative abundance ofKandleria compared with low-MUNBV dairy cattle. Greater relative abundances ofKandleria may be affecting the health status of dairy cattle classified as high MUNBV resulting in greater incidences of increase SCC. Knowledge of differences in the relative abundance of the rumen microbiota of dairy cows divergent for MUNBV highlights areas where future research is required as well as the potential for using MUNBV as a metric for increasing animal welfare.