** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** RATIONALEA DAUNTING CHALLENGE FACED BY FARMING COMMUNITIES AND ANIMAL SCIENTISTS IS TO DEFINE ANIMAL WELFARE STANDARDS OWING TO THE ETHICAL, ECONOMIC, AND SCIENTIFIC DEBATES AROUND CARE AND MANAGEMENT OF AGRICULTURAL ANIMALS. EFFORTS HAVE FOCUSED ON REDUCING STRESS, PAIN, ANXIETY, AND DEVIATION FROM NATURE IN INTENSIVE FARMING SYSTEMS, ALL OF WHICH HAVE BECOME SOCIETAL CONCERNS. A RISING TREND IN ANIMAL WELFARE IS ALSO TO PROMOTE A GOOD LIFE WHICH INCLUDES POSITIVE AFFECTIVE STATES. HOWEVER, QUESTIONS REMAIN ON THE MECHANISTIC BASIS INFLUENCING DIFFERENT TYPES OF BEHAVIOR. RESEARCH IN HUMANS HAS DEMONSTRATED THAT THE EARLY LIFE MICROBIOME IS ESSENTIAL FOR PROPER DEVELOPMENT OF THE ENTERIC AND CENTRAL NERVOUS SYSTEMS, THE IMMUNE SYSTEM, AND THE MICROBIOME-GUT-BRAIN AXIS (MGBA). FURTHER, EARLY LIFE MICROBIAL DYSBIOSIS MAY LEAD TO AN INCREASED INCIDENCE OF DISEASED STATES, INCLUDING BEHAVIORAL ISSUES, LATER IN LIFE. SUCH STUDIES HAVE NOT BEEN REPORTED IN AGRICULTURAL ANIMALS. THE PREMISEFOR THIS GRANT IS THAT STRONG BI-DIRECTIONAL CONNECTIONS EXIST BETWEEN MICROBIOME-GUT-BRAIN AXIS (MGBA) THAT THEN EFFECTS ANIMAL BEHAVIOR IN DAIRY CATTLE.HYPOTHESISTHE OVERALL GOAL OF THIS RESEARCH IS TO DETERMINE IF FAECALIBACTERIM PRAUSNITZII WHEN USED IN CALVES CAN ALTER THE IMMUNE RESPONSE, REDUCE STRESS-INDUCED RESPONSES AND HAVE LASTING EFFECTS ON POSITIVE BEHAVIOR IN DAIRY CATTLE. WE HYPOTHESIZE THAT PERTURBING GUT MICROBIOTA (DYSBIOSIS) EARLY IN DAIRY CALVES' LIVES MAY INDUCE SYSTEMIC CHANGES LEADING TO ALTERATIONS IN BEHAVIOR AND THAT SUPPLEMENTATION WITH FAECALIBACTERIUM PRAUSNITZII, A BUTYRATE PRODUCING BACTERIUM MAY PREVENT MICROBIAL DYSBIOSIS AND REDUCE STRESS-INDUCED BEHAVIORS THUS IMPROVING HEALTH, WELL-BEING, AND WELFARE.SPECIFIC OBJECTIVESOBJECTIVE 1: DETERMINE THE EXTENT TO WHICH EARLY-LIFE MICROBIAL DYSBIOSIS ALTERS PHYSIOLOGICAL RESPONSES AND BEHAVIOR (MICROBIOME-GUT-BRAIN AXIS) AND IF SUCH ALTERATIONS ARE REVERTED BY DOSING CALVES WITH F. PRAUSNITZII IN DAIRY CALVES AND SUSTAINED FOR LONGER PERIODS. OBJECTIVE 2: DETERMINE THE EFFECTS OF DOSING F. PRAUSNITZII ON REVERSING STRESS-INDUCED BEHAVIORS SUCH AS DEHORNING AND TRANSPORTATION IN DAIRY CALVES.THESE TWO OBJECTIVES WILL BE ACCOMPLISHED BY PERFORMING TWO ANIMAL EXPERIMENTS. THE STUDY WILL USE DAIRY CALVES. THE FIRST PHASE TO DETERMINE IMMUNE AND BEHAVIORAL RESPONSES WILL USE NEWBORN CALVES AND THEY WILL BE DIVIDED INTO 3 GROUPS: ORAL ANTIBIOTICS, ORAL ANTIBIOTIC PLUS PROBIOTIC AND CONTROL GROUP. THE CALVES WILL STAY IN THE STUDY FOR 24 MONTHS. THE 2ND PHASE TO DETERMINE PROBIOTIC EFFECTS ON STRESS INDUCED RESPONSES WILL USE 5-6 WEEK OLD CALVES. THE CALVES WILL BE IN TWO GROUPS: ORAL PROBIOTIC AND CONTROL. THESE CALVES WILL BE ENROLLED FOR 12 WEEKS.EXPECTED RESULTSWE ANTICIPATE THAT THIS PROJECT WILL AUGMENT OUR CURRENT RESEARCH ACTIVITIES AND ENHANCE OUR KNOWLEDGE OF THE ROLE OF THE GUT MICROBIOME IN IMPROVING HEALTH, WELL-BEING, WELFARE, AND PRODUCTION PERFORMANCE IN AGRICULTURAL ANIMALS.,USING STRESSORS AND POSITIVE WELFARE TESTS COMBINED WITH MICROBIOME, METABOLOMIC, AND SYSTEMIC RESPONSES, WE WILL DETERMINE THE LINK BETWEEN THE MGBA AND BEHAVIOR AND ALSO DETERMINE THE EFFICACY OF F. PRAUSNITZII AS A PSYCHOBIOTIC TO IMPROVE HEALTH AND BEHAVIOR IN DAIRY CATTLE.ANTICIPATED IMPACTWITH A STRONG, INTERDISCIPLINARY TEAM OF VETERINARIANS, WE ANTICIPATE THIS PROJECT WILL BE A SCIENTIFIC BREAKTHROUGH IN DEVELOPING NOVEL EARLY LIFE MICROBIAL INTERVENTIONS TO IMPROVE HEALTH, WELFARE, AND WELL-BEING OF DAIRY CATTLE VIA CHOREOGRAPHING DEVELOPMENT OF THE MGBA.