** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** METRICS FOR BEEF BULL FERTILITY INCLUDE ONLY TWO TOOLS: BREEDING SOUNDNESS EXAMINATION (BSE) AND AN EXPECTED PROGENY DIFFERENCE (EPD) FOR SCROTAL CIRCUMFERENCE (SC). BECAUSE BSES ARE PRIMARILY A CULLING TOOL, SC EPD IS THE ONLY MALE FERTILITY SELECTION TOOL IN THE BEEF INDUSTRY. RESEARCH INDICATES THAT SEMEN QUALITY IS MORE HERITABLE THAN FEMALE REPRODUCTIVE TRAITS, AND THE GENETIC CORRELATION BETWEEN MALE AND FEMALE FERTILITY IS LOW, SO SELECTION PROGRESS CAN BE MADE IN BOTH TRAITS SIMULTANEOUSLY.THIS PROJECT WILL RESULT IN PROTOTYPE SELECTION TOOLS FOR BULL FERTILITY UTILIZING CONCEPTION DATA, SEMEN QUALITY METRICS, AND BSE DATA ON BEEF BULLS. WE WILL UTILIZE BOTH TRADITIONAL QUANTITATIVE GENETIC METHODOLOGIES AND INCORPORATE GENOMIC DATA. BY THE CONCLUSION OF THIS PROJECT, THE BEEF INDUSTRY WILL BE POISED TO IMPLEMENT MALE FERTILITY TRAITS INTO THEIR GENETIC EVALUATION SYSTEMS. CREATION OF THESE TOOLS AND IDENTIFYING GENETICALLY CORRELATED TRAITS WILL POSITION THE INDUSTRY TO RESPOND TO THE NEED FOR SELECTION ON MALE FERTILITY AS WELL AS CONSTRUCT ECONOMIC SELECTION INDICES THAT PRODUCERS CAN USE TO EASILY SELECT ON MULTIPLE TRAITS THAT MAY BE ANTAGONISTIC.THE RESEARCH ACTIVITIES IN THIS PROPOSAL WILL INCREASE UNDERSTANDING OF THE TRAITS THAT IMPACT MALE FERTILITY AND PROVIDE CATTLE PRODUCERS WITH SELECTION TOOLS TO CAPITALIZE ON THIS KNOWLEDGE, MAKING BEEF PRODUCTION MORE PROFITABLE AND SUSTAINABLE. THESE OUTCOMES ADDRESS THE ANIMAL BREEDING AND FUNCTIONAL ANNOTATION OF GENOMES PRIORITIES, MOST NOTABLY DEVELOPMENT OF NEW PHENOTYPES FOR IMPROVING SELECTION CRITERIA AND SYSTEMS APPROACHES FOR USING GENOMICS FOR SIMULTANEOUS IMPROVEMENT OF MULTIPLE TRAITS.