SUBACUTE RUMINAL ACIDOSIS AND LIVER ABSCESSES HAVE PLAGUED THE FEEDLOT INDUSTRY BY DECREASING NUTRIENT UTILIZATION AND GROWTH PERFORMANCE IN CATTLE. AS A RESULT, ANTIBIOTICS ARE WIDELY FED TO SUPPRESS LIVER ABSCESSES. PREVENTATIVE MEASURES FOR ACIDOSIS ARE THE MOST EFFECTIVE SINCE IT COMMONLY DOES NOT HAVE CLINICAL SYMPTOMS IN PRODUCTION ANIMALS. WE HYPOTHESIZE PRECISION MANAGEMENT CAN BE USED TO TARGET CATTLE AT GREATEST RISK FOR ACIDOSIS AND THAT BETTER NUTRITIONAL STRATEGIES CAN BE DEVELOPED THROUGH A BETTER UNDERSTANDING OF HOW ACIDOSIS DEVELOPS IN FEEDLOT CATTLE. SINCE THE SUSCEPTIBILITY TO ACIDOSIS VARIES WIDELY IN CATTLE FOR UNKNOWN REASONS, WE WILL IDENTIFY CATTLE AT THE GREATEST RISK AND EVALUATE A NUTRITIONAL STRATEGY TO REDUCE THE PREVALENCE OF ACIDOSIS. ADDITIONAL EXPERIMENTS WILL ALSO EVALUATE THE ENERGETIC COSTS OF A RUMINAL ACIDOSIS BOUT AND DETERMINE THE EFFECT OF ACIDOSIS IN THE HINDGUT ON GUT PERMEABILITY. BY STUDYING SUBACUTE RUMINAL ACIDOSIS IN A PRODUCTION SETTING, WE WILL BE ABLE TO DETERMINE THE DRIVING FACTORS BEHIND THESE CONDITIONS AND THEIR RELATIONSHIP TO GUT MICROBIOTA, ANIMAL FEEDING BEHAVIORS, BLOOD METABOLITES, AND INFLAMMATORY FACTORS. THIS RESEARCH WILL TRANSLATE TO IMPROVED MANAGEMENT OF FEEDLOT CATTLE BY REDUCING ACIDOSIS IN FEEDLOT CATTLE AND THE DEPENDENCE ON ANTIBIOTICS TO MANAGE LIVER ABSCESSES. COLLECTIVELY, THIS RESEARCH WILL FILL A CRITICAL KNOWLEDGE GAP IN FEEDLOT NUTRITION AND IMPROVE PRODUCTION EFFICIENCY TO MORE SUSTAINABLY PRODUCE BEEF FOR A U.S. POPULATION GROWING IN NUMBER AND CONCERN ABOUT ANTIBIOTIC USE IN FOOD PRODUCTION.