**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** GILTS, OR YOUNG FEMALE PIGS, REPRESENT THE FUTURE PRODUCTION OF A SWINE HERD. A KEY FACTOR AFFECTING PRODUCTIVITY AND OVERALL PROFITABILITY OF A BREEDING HERD IS THE SELECTION OF GILTS WITH THE GREATEST LIFETIME REPRODUCTIVE POTENTIAL. HOWEVER, CURRENTLY, AS MANY AS 20-25% OF SELECTED REPLACEMENT GILTS MAYBE INFERTILE, AND AN UNRECOGNIZED NUMBER, SUB-FERTILE. THE FUNDAMENTAL QUESTIONS DRIVING THE PROPOSED PROJECT CENTER AROUND WELL-ESTABLISHED OBSERVATIONS THAT LONG-TERM FERTILITY OF FEMALE SWINE IS SET BY THE AMOUNT OF COLOSTRUM THEY INTAKE THE FIRST 24 H AFTER THEY ARE BORN. COLOSTRUM IS THE FIRST MILK AVAILABLE TO NEONATES AFTER BIRTH. COLOSTRUM IS MORE THAN NUTRITION. IT CONTAINS BIOACTIVE FACTORS ESSENTIAL FOR NEONATAL SURVIVAL, GROWTH AND DEVELOPMENT. THE OVERALL DRIVE OF THIS STUDY IS TO UNDERSTAND THE FUNDAMENTAL BIOLOGY THAT LINKS THE AMOUNT OF COLOSTRUM CONSUMED IN THE FIRST DAYS POSTNATAL TO LONG-TERM FERTILITY. WE HYPOTHESIZE THAT COLOSTRUM STIMULATES THE PRODUCTION OF CELL ORGANELLES CALLED PEROXISOMES. PEROXISOMES BREAKDOWN AND SYNTHESIZE FATS, I.E. LIPIDS, THAT ACT AS SIGNALING MOLECULES THAT MAY AFFECT THE DEVELOPMENT OF THE REPRODUCTIVE SYSTEM. THE OVERALL GOAL OF THE PROPOSED PROJECT IS TO ESTABLISH THE LINK BETWEEN COLOSTRUM INTAKE AND INDUCTION OF PEROXISOME BIOGENESIS AND METABOLITES WITH FERTILITY IN SWINE. COMPLETING THE FOLLOWING OBJECTIVES WILL ENABLE THE MEETING OF THIS GOAL: 1) FEED GILTS DIFFERENT AMOUNTS OF COLOSTRUM OR MILK REPLACER FORMULA AND MEASURE SYNTHESIS OF PEROXISOMES IN MULTIPLE TISSUES; 2) MEASURE THE RELATIONSHIP BETWEEN LIPIDS MADE OR BROKEN DOWN BY PEROXISOMES TO FERTILITY OF MATURE GILTS. WE ENVISION THAT ESTABLISHING A LINK BETWEEN COLOSTRUM, PEROXISOMES AND RELATED METABOLITES WITH FERTILITY IN GILTS WILL ENABLE THE LAUNCHING OF MULTIPLE PROGRAMS OF STUDY THAT ADVANCE THE EFFICIENCY OF SWINE PRODUCTION. AT THE BASIC BIOLOGICAL LEVEL, THESE FINDINGS WOULD SUPPORT DESIGNING STUDIES TO DETERMINE HOW AND IF PEROXISOME LIPIDS AFFECT EARLY REPRODUCTIVE SYSTEM DEVELOPMENT AND LONG-TERM FERTILITY. AT THE TRANSLATIONAL LEVEL, THESE STUDIES WOULD SUPPORT INVESTIGATIONS INTO HOW TO FEED SOWS TO ALTER THEIR MILK OR SUPPLEMENT NEONATES TO BETTER STIMULATE PEROXISOME SYNTHESIS, AND THEN DETERMINE THE IMPACT OF LONG-TERM DEVELOPMENT, FERTILITY AND PRODUCTION EFFICIENCY. FINDINGS FROM THESE STUDIES CAN ALSO ESTABLISH LIPID BIOMARKERS PREDICTIVE OF GILT LONG-TERM FERTILITY AND ENABLE PRODUCERS TO SELECT SUPERIOR ANIMALS EARLY IN THEIR DEVELOPMENT.