USING METATRANSCRIPTOMICS TO INVESTIGATE THE LIVER AND BLOOD MICROBIOME IN DAIRY CATTLE WITH FEED-INDUCED ACIDOSIS

Subacute ruminal acidosis (SARA) has long been considered an animal production, health, and welfare issue. SARA has high incident rates in two critical phases in dairy production: weaning period in young calves and mid-lactation period in dairy cattle. As a sequela to SARA, liver abscess causes liver function damage and premature culling. Currently, a well-defined, accurate diagnostic tool is lacking for the diagnosis and prevention of SARA. Microbial dysbiosis triggered by impaired gut barrier in these tissue-embedded microbial communities is strongly correlated with various metabolic and digestive diseases. Liver and blood microbiome (LBM)and its relation to host gut health is largely unexplored in cattle. Using metatranscriptomics as the main approach, the overarching goals of our proposal are 1) to investigate membership and longitudinal shifts in the LBM; and 2) to establish a correlation between LBM and feed-induced acidosis during the weaning period in young calves and the mid-lactation in adult cows. Identification of a dynamic and responsive microbiome within the liver will be transformative for delineating molecular mechanisms influenced by the gut microbiome that impact cattle nutritional and physiological functions. The expected associations between LBM changes and feed-induced acidosis resultant from this project will greatly advance investigations into the causative role of host-microbe interactions in predisposition to and development of SARA in dairy cattle.