CATTLE CONVERT CROPS LIKE GRASS AND FOOD BYPRODUCTS TO HIGH-QUALITY PROTEIN LIKE MILK AND MEAT. MICROORGANISMS THAT LIVE IN THE COW'S FIRST STOMACH CHAMBER, CALLED THE RUMEN, INITIALLY DIGEST THESE FEEDS, AND THE COW LIVES ON THE BYPRODUCTS OF THE DIGESTION AND THE MICROBES THEMSELVES. HOWEVER, THIS DIGESTION AND FERMENTATION PROCESS ALSO RELEASES METHANE GAS, WHICH REPRESENTS A LOSS OF 2% TO 10% OF THE ENERGY IN THE DIET, AND IT IS A POTENTIAL GREENHOUSE GAS. THE GOAL OF THE PROPOSED RESEARCH IS TO IMPROVE THE WAY DIGESTION OCCURS IN THE COW'S RUMEN TO DECREASE METHANE EMISSIONS AND TO THEREBY INCREASE THE EFFICIENCY AND IMPROVE THE ENVIRONMENTAL IMPACT OF FOOD PRODUCTION FROM AVAILABLE FEEDS. THE OVERARCHING HYPOTHESIS FOR THIS RESEARCH IS THAT MATHEMATICAL MODELS OF FERMENTATION BASED ON CLASSICAL LAWS OF PHYSICS CAN EXPLAIN AND PREDICT THE PROFILE OF END PRODUCTS FROM FERMENTATION IN THE COW'S RUMEN. SPECIFIC OBJECTIVES INCLUDE STUDYING THE WAY DIFFERENT NUTRIENTS AND PROBIOTICS IN THE DIET CAUSE SHIFTS IN METABOLISM BASED ON LAWS OF PHYSICS. WE EXPECT THIS RESEARCH TO SHOW HOW TO REGULATE DIFFERENT FERMENTATION PATHWAYS TO IMPROVE EFFICIENCIES OF PRODUCTION AND HEALTH, AND ULTIMATELY TO IDENTIFY WAYS TO DECREASE WASTEFUL METHANE EMISSIONS FROM CATTLE. RESULTS WILL BE USED TO IMPROVE RATION FORMULATION FOR CATTLE, AND TO PREDICT ENERGY AND PROTEIN AVAILABILITY FOR DIFFERENT FEEDS.