CATTLE SUBFERTILITY RESULTS IN ECONOMIC LOSS DUE TO THE EXTENDED CALVING INTERVAL AND REDUCED PRODUCTION OF MILK. THE AVERAGE CONCEPTION RATE IS ONLY ~32% FOR ARTIFICIAL INSEMINATION (AI). IF CONCEPTION RATE COULD BE IMPROVED, EVEN A FEW PERCENT, IT COULD SAVE FARMERS VALUABLE TIME AND INCREASE COST EFFICIENCY. FURTHERMORE, HUMAN MALE FERTILITY HAS BEEN DECLINING WORLDWIDE, WITH A LARGE PERCENT OF THOSE BEING DUE TO UNEXPLAINED CAUSES. ONE POTENTIAL CAUSE OF HUMAN CATTLE SUBFERTILITY IS CONDITIONS LEADING TO DEFECTIVE SPERM CENTRIOLES; NOTABLY, THE CENTRIOLES ARE THE ONLY CYTOPLASMIC STRUCTURES THAT ARE PROVIDED EXCLUSIVELY BY THE SPERM.USING A NOVEL GENETIC MODEL THAT HAS A KNOWN MUTATION OF THE CENTRIOLAR GENE POC1B WE CAN EVALUATE THE ESSENTIAL FUNCTIONS OF SPERM CENTRIOLES. THIS WILL BE ACCOMPLISHED USING CONFOCAL, STORM, AND HIGH-SPEED VIDEO IMAGING MICROSCOPY OF SPERM TO EVALUATE MULTIPLE ASPECTS OF THE SPERM CENTRIOLES AND THE DIFFERENCES BETWEEN WILD-TYPE AND MUTANT SPERM. THEDATA GENERATED BY THIS PROJECT WILL REVEAL ROLE OF POC1B IN SPERM CENTRIOLES AND FERTILITY. THESE RESULTS WILL ALSO BE COMPARED TO OUR PREVIOUS CATTLE DATA TO DRAW BROADER CONCLUSIONS ON HOW THE SPERM CENTRIOLES CONTRIBUTE TO MALE FERTILITY. WITH THIS UNDERSTANDING WE CAN DEVELOP TESTS AND TREATMENTS FOR CENTRIOLE-BASED MALE INFERTILITY FOR BOTH CATTLE AND HUMANS.