** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE HORSE INDUSTRY IS A VITAL COG IN THE US ECONOMY GENERATING NEARLY $120-BILLION ANNUALLY. THE ATHLETIC PROWESS OF THE HORSE DEMANDS LARGE ENERGY EXPENDITURES DURING MUSCLE MOVEMENT WHICH OFTEN LEADS TO DAMAGE. REPAIR OF SKELETAL MUSCLE, AND TISSUE GROWTH, NECESSITATES THE ACTIVITIES OF MUSCLE STEM CELLS (SATELLITE CELLS, SCS). THESE CELLS, HOWEVER, ARE A MIX OF MULTIPLE SUBTYPES WITH EACH LIKELY PLAYING DISTINCT ROLES. TO FACILITATE MUSCLE GROWTH AND REPAIR, AN IMPROVED UNDERSTANDING OF HOW THESE CELLS DIFFER FROM ONE ANOTHER, HOW THEIR ACTIONS ARE INITIATED FOLLOWING METABOLIC CHALLENGES AND HOW NUTRITION CAN REGULATE THE TIMING OF THEIR ACTIVATION IS REQUIRED. USING MOLECULAR AND BIOCHEMICAL TOOLS, WE EXPECT TO FIND RAPID-FUSING SC THAT LAY THE FOUNDATION FOR EARLY REPAIR AND GROWTH AND A SECOND POPULATION RESPONSIBLE FOR GENERATING SC PRECURSORS. SUPPLEMENTING BUTYRATE-PRODUCTS TO HORSES WILL ALTER THE FIBER METABOLISM AND INITIATE SC ACTIVITY. COMPLETION OF THE PROPOSED EXPERIMENTS WILL ASSIST WITH MUSCLE RECOVERY FROM EXERCISE THUS, IMPROVING THE HEALTH AND WELFARE OF THE HORSE. EQUALLY IMPORTANT, FILLING THE KNOWLEDGE VOIDS SURROUNDING SC BIOACTIVITIES CAN TRANSLATE DIRECTLY TO LIVESTOCK PRODUCTION LEADING TO AN IMPROVED EFFICIENCY OF LEAN MUSCLE DEPOSITION AND CONTRIBUTING TO A SUSTAINABLE FOOD SUPPLY.