** 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 GLOBAL POPULATION HAS BEEN RISING AND IS EXPECTED TO REACH OVER 9 BILLION PEOPLE BY THE YEAR 2050. TO HELP FEED THIS GROWING GLOBAL POPULATION, CURRENT AGRICULTURAL PRACTICES MUST BE EVALUATED FOR EFFICIENCY AND PRODUCTION CAPACITY. IN ADDITION TO A GROWING POPULATION SIZE CONCOMITANT CHALLENGES REGARDING FRESHWATER AVAILABILITY AND RISING AVERAGE GLOBAL TEMPERATURES HAVE ARISEN. MANY COUNTRIES INCLUDING THE UNITED STATES ARE NOW EXPERIENCING UNPRECEDENTED BOUTS OF FRESHWATER SCARCITY AND SUSTAINED PERIODS OF HEAT STRESS. HEAT STRESS CREATES AN ADDITIONAL CHALLENGE IN AGRICULTURAL PRODUCTION THROUGH DECREASES IN YIELDS AND EFFICIENCIES, INCREASES IN WATER CONSUMPTION AND INCREASED RATES OF MORTALITY. FINDING METHODS OF DECREASING WATER USAGE IN AGRICULTURE, PARTICULARLY UNDER POTENTIAL PERIODS OF HEAT STRESS IS IMPERATIVE FOR CREATING A WATER AND FOOD SUSTAINABLE FUTURE.AS WATER IS REGARDED AS THE MOST IMPORTANT NUTRIENT, FURTHER UNDERSTANDING OF MECHANISMS REGARDING THE RELATIONSHIP OF WATER UTILIZATION, GROWTH AND MEAT QUALITY ARE OF HIGH IMPORTANCE. IT IS ALSO IMPORTANT TO UNDERSTAND HOW THE ENVIRONMENT, PARTICULARLY PERIODS OF HEAT STRESS CAN IMPACT THESE RELATIONSHIPS. THE SUCCESSFUL COMPLETION OF THIS RESEARCH WILL SERVE AS THE FIRST STEP IN UNDERSTANDING WATER EFFICIENCY MECHANISMS IN COMMERCIAL BROILERS AND HOW SELECTION FOR IMPROVED WATER EFFICIENCY CAN BE UTILIZED IN SELECTION INDICES TO CREATE A MORE WATER SUSTAINABLE FUTURE. AS EACH SUBOBJECTIVE IS INDEPENDENT OF THE NEXT, THIS PROJECT IS POISED TO IDENTIFY RELATIONSHIPS BETWEEN WATER EFFICIENCY, GROWTH, MEAT QUALITY AND HEAT STRESS ADAPTATION AND WILL PROVIDE INSIGHT ON NUMEROUS NEW DIRECTIONS FOR FUTURE RESEARCH PROJECTS.SELECTION FOR WATER EFFICIENCY IN BROILERS HAS BEEN A THOUGHT FOR MANY YEARS, HOWEVER HAVING THE ABILITY AND THE TECHNOLOGY TO ACCURATELY SELECT HAS BEEN LIMITED. WITH GROWING CONCERNS ABOUT WATER USAGE AND THE TIE TO LITTER MOISTURE, FOOTPAD HEALTH AND BROILER WELFARE, THE INDUSTRY HAS SHOWN SIGNIFICANT ENTHUSIASM FOR SELECTION FOR WATER EFFICIENCY. AT THE UNIVERSITY OF ARKANSAS, A DIVERGENT SELECTION PROGRAM FOR WATER CONVERSION RATIO IN BROILERS HAS BEEN ESTABLISHED. BROILER LINES HAVE BEEN CREATED FROM A RANDOMBRED CONTROL POPULATION THAT ARE DIVERGENTLY SELECTED FOR BOTH HIGH (HWCR) AND LOW (LWCR) WATER CONVERSION RATIO. THESE LINES HAVE BEEN SELECTED FOR 4 GENERATIONS AND SHOW CLEAR DIVERGENCE AS WELL AS A MODERATE HERITABILITY FOR WATER EFFICIENCY RELATED TRAITS. THESE ARE THE FIRST DOCUMENTED MODELS FOR WATER EFFICIENCY IN COMMERCIAL BROILERS AND ARE THE BACKBONE OF THE PROPOSED RESEARCH.WITH ESTABLISHED MODELS FOR WATER EFFICIENCY, UTILIZING THE HWCR, LWCR AND RANDOMBRED CONTROL THE FIRST OBJECTIVE WILL AIM TO ESTABLISH RELATIONSHIPS BETWEEN WATER EFFICIENCY, YIELD, AND MEAT QUALITY. BECAUSE SELECTION FOR WATER EFFICIENCY HAS NOT BEEN EXTENSIVELY STUDIED, IT IS UNCLEAR WHAT IMPACT SELECTION FOR IMPROVED WATER EFFICIENCY MAY HAVE ON YIELD AND MEAT QUALIT,Y. OUR HOPE IS THAT SELECTION HAS NOT HAD A NEGATIVE IMPACT ON MEAT QUALITY. BASED ON PRELIMINARY DATA COLLECTED FROM THE LINES, BODY WEIGHT HAS NOT YET BEEN AFFECTED AND IT APPEARS THAT THE LWCR, A LINE SELECTED TO BE MORE WATER EFFICIENT, MAY HAVE BEEN WATER UTILIZATION CAPABILITIES THROUGH IMPROVED WATER HOMEOSTASIS. WATER HOMEOSTASIS MECHANISMS IS THE MAIN FOCUS FOR THE SECOND OBJECTIVE. THIS OBJECTIVE WILL UTILIZE THE LWCR AND HWCR LINES UNDER PERIODS OF EITHER A THERMONEUTRAL ENVIRONMENT (TN) OR A PERIOD OF CHRONIC, DAILY HEAT STRESS (HS). LIVE PERFORMANCE AND EFFICIENCY RELATED MEASUREMENTS SUCH AS BODY WEIGHT, FEED AND WATER INTAKE, AND FEED AND WATER CONVERSION WILL BE MEASURED. AT THE END OF THE STUDY, SAMPLES WILL BE COLLECTED FROM MULTIPLE TISSUES AND SUBJECTED TO A MULTI-OMICS APPROACH. THIS MULTI-OMICS APPROACH WILL HELP TO IDENTIFY HOW WATER EFFICIENCY SELECTION AND HEAT STRESS AFFECT WATER HOMEOSTASIS IN THE COMMERCIAL BROILER. UNDERSTANDING THESE PATHWAYS WILL HELP US TO BETTER UNDER SELECTION FOR WATER EFFICIENCY AND DETERMINE A PATH FORWARD FOR CREATING A MORE WATER EFFICIENT BROILER. INFORMATION DETERMINED FROM THESE STUDIES HAVE THE POTENTIAL TO BE APPLIED TO OTHER SPECIES FOR IMPROVED WATER EFFICIENCY, HEAT STRESS TOLERANCE AND OVERALL SUSTAINABLE OF THE AGRICULTURAL COMMUNITY. WHILE FRESHWATER AVAILABILITY MAY CURRENTLY BE TAKEN FOR GRANTED, IT IS UNCLEAR WHAT MAY HAPPEN IN THE FUTURE WITH REGARDS TO OUR RESOURCES. TO FEED THE GROWING POPULATION, WE MUST ENSURE A WATER EFFICIENT AND SUSTAINABLE FUTURE IN AGRICULTURAL PRODUCTION.