IN UTERO HEAT STRESS IS AN EMERGING AND CRITICAL ANIMAL WELFARE ISSUE. AS GLOBAL TEMPERATURES RISE AND SELECTION FOR IMPROVED PERFORMANCE INCREASES HEAT STRESS SENSITIVITY IN GESTATING SOWS, THE RISK OF PRODUCING IN UTERO HEAT STRESS PIGS WILL INCREASE RESULTING IN A LIFETIME OF POOR HEALTH AND WELFARE FOR PIGS. POSTNATAL IN UTERO HEAT STRESS PHENOTYPES INCLUDE GREATER STRESS SENSITIVITY, COMPROMISED IMMUNITY, DECREASED THERMOTOLERANCE, AND REDUCED PERFORMANCE. ADDITIONALLY, IN UTERO HEAT STRESS PHENOTYPES ARE TRANSMITTED ACROSS GENERATIONS CAUSING POOR WELFARE IN FUTURE OFFSPRING. THE MOST EFFECTIVE METHOD TO MITIGATE IN UTERO HEAT STRESS IS DECREASING THE IN-BARN TEMPERATURE. HOWEVER, THE ASSOCIATED ENERGY INPUTS MAKE COOLING TECHNOLOGIES COST-PROHIBITIVE FOR MANY PRODUCERS. BECAUSE A PRIMARY RISK FACTOR FOR PRODUCING IN UTERO HEAT STRESS PIGS IS GREATER SOW HEAT STRESS SENSITIVITY (A HERITABLE TRAIT), GENOMIC SELECTION MAY BE A PROMISING IN UTERO HEAT STRESS MITIGATION STRATEGY, ESPECIALLY AS GENETIC GAINS ARE PERMANENT AND CUMULATIVE. THEREFORE, THIS INTEGRATED PROPOSAL AIMS TO DEVELOP A FUNCTIONAL GENOMICS APPROACH TO ENABLE SELECTIVE BREEDING OF SOWS THAT ARE AT A REDUCED RISK OF PRODUCING OFFSPRING WITH NEGATIVE IN UTERO HEAT STRESS PHENOTYPES. TO ACHIEVE THIS GOAL, WE WILL WORK WITH SWINE BREEDING COMPANIES TO OBTAIN LARGE SCALE GENOMIC DATASETS AND DEVELOP GENOMIC MODELS TO SELECT SOWS THAT ARE AT LOW RISK OF PRODUCING OFFSPRING DISPLAYING THE IN UTERO HEAT STRESS PHENOTYPES. THE GENOMIC SELECTION MODELS WILL BE BIOLOGICALLY VALIDATED THROUGH BEHAVIORAL, PHYSIOLOGICAL AND EPIGENOMIC STUDIES IN GENETICALLY DIVERGENT ANIMALS. COMPLETION OF THIS PROJECT WILL PROVIDE PRODUCERS WITH A COST-EFFECTIVE STRATEGY TO REDUCE THE NEGATIVE IMPACT OF IN UTERO HEAT STRESS ON SWINE WELFARE IN THE U.S. AND GLOBALLY.