**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** OUR PROPOSED RESEARCH WILL ADVANCE THE KNOWLEDGE OF GUT HEALTH IN DAIRY CATTLE. GUT HEALTH IS A HOT TOPIC IN THE INDUSTRY AND MAY HAVE LARGE EFFECTS ON ANIMAL HEALTH PRODUCTIVITY AND EFFICIENCY BUT WE DO NOT HAVE A THOROUGH KNOWLEDGE OF THE DAIRY COWS RUMEN TISSUE OR ITS RESIDENT IMMUNE CELLS. ESPECIALLY WE DO NOT KNOW HOW THE DIET FED TO THE COW MAY AFFECT THESE TISSUES OR THESE CELLS. BUILDING OUR UNDERSTANDING OF HOW DIET CAN AFFECT THE RUMEN TISSUE AND RUMEN IMMUNE CELLS WILL PROVIDE STRATEGIES TO FEED COWS IN A WAY THAT IMPROVE THE HEALTH OF THEIR GASTROINTESTINAL TRACT WHICH WILL IMPROVE ANIMAL WELFARE HEALTH AND SUSTAINABILITY.WE ARE GOING TO FEED DAIRY COWS RATIONS WITH DIFFERENT TYPES OF GRAIN AND DIFFERENT AMOUNTS OF THOSE GRAINS. THEN WE WILL COLLECT RUMEN TISSUE FROM THESE COWS AND MEASURE THE IMMUNE CELLS PRESENT IN THE TISSUE. THIS WILL ALLOW US TO DETERMINE HOW DIET MAY AFFECT THE RUMEN TISSUE AND THE IMMUNE CELLS WITHIN IT.OUR ULTIMATE GOAL FROM THIS RESEARCH IS THAT WE CAN USE DIETS FEED ADDITIVES OR DIFFERENT STRATEGIES TO IMPROVE THE GUT HEALTH OF ANIMALS. TO REACH THAT GOAL WE MUST CONTINUALLY GROW OUR KNOWLEDGE OF HOW THE RUMEN AND RUMINAL IMMUNE CELLS MAY CHANGE UNDER VARIOUS CONDITIONS. ONCE WE DO THIS WE WILL STEADILY BE ABLE TO IMPROVE ANIMAL HEALTH AND WELFARE.