** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** RESILIENCE, A KEY COMPONENT OF ROBUSTNESS, IS A PIG'S ABILITY TO QUICKLY RECOVER FROM A STRESSOR OR BE MINIMALLY AFFECTED BY THE STRESSOR. SOCIAL STRESS IS A SIGNIFICANT THREAT TO PIG ROBUSTNESS AND IS A CRITICAL ISSUE AS THE INDUSTRY TRANSITIONS TO GROUP HOUSING OF GESTATING FEMALES. OUR OVERALL GOAL IS TO ENSURE SUSTAINABLE, EFFICIENT PORK PRODUCTION BY ESTABLISHING MEASURES OF PIG RESILIENCE AND CONTRIBUTING FOUNDATIONAL KNOWLEDGE TO INFORM GENETIC SELECTION FOR MORE ROBUST PIGS RESILIENT TO EXTERNAL STRESSORS. THE PROPOSED PROJECT WILL EVALUATE SOCIAL STRESS BY INTEGRATING GENE EXPRESSION DATA WITH PHYSIOLOGICAL AND BEHAVIORAL PHENOTYPES TO ADVANCE ASSESSMENT OF PIG RESILIENCE. A TWO-GENERATION MODEL WILL BE USED TO EVALUATE EFFECTS OF PRENATAL STRESS FROM GROUP GESTATIONAL HOUSING ON OFFSPRING RESILIENCE. OUR SPECIFIC AIMS ARE (1) CHARACTERIZE STRESS RESILIENCE IN PIGS AT WEANING AND ESTIMATE EFFECTS ON FUTURE STRESS RESPONSE; (2) IDENTIFY SOWS EXHIBITING VARYING STRESS RESPONSES IN GROUP HOUSING DURING GESTATION AND INVESTIGATE MOLECULAR AND PHENOTYPIC DIFFERENCES AMONG THEIR OFFSPRING AT PARTURITION; AND (3) CHARACTERIZE DIFFERENCES IN STRESS RESPONSE AND BEHAVIOR OF OFFSPRING ASSOCIATED WITH PRENATAL SOCIAL STRESS AND ELUCIDATE UNDERLYING MOLECULAR MECHANISMS. RESULTS OF THIS RESEARCH WILL BE USED TO ESTIMATE THE EFFECTS OF SOCIAL STRESS ON PIG RESILIENCE AND SUPPORT ONGOING EFFORTS TO DEVELOP STRATEGIES TO SELECT FOR RESILIENT, AND THEREFORE ROBUST, PIGS. CHARACTERIZING INDIVIDUALS BASED ON ABILITY TO COPE WITH SOCIAL STRESS WILL ALLOW PIGS TO BE MANAGED OPTIMALLY AND MITIGATE DETRIMENTAL EFFECTS ON OFFSPRING.