CATTLE PRODUCTION REPRESENTS THE LARGEST ECONOMIC SECTOR OF AGRICULTURE IN THE UNITED STATES, WORTH OVER $67 BILLION TO THE UNITED STATES ECONOMY IN 2018. GROWTH-ENHANCING TECHNOLOGIES, SUCH AS ANABOLIC IMPLANTS, INCREASE BEEF PRODUCTION PER ANIMAL, WHILE MORE EFFICIENTLY USING NATURAL RESOURCES. ANABOLIC IMPLANTS PROVIDE SMALL AMOUNTS OF THE HORMONES ESTRADIOL AND TRENBALONE ACETATE, TO STIMULATE MUSCLE GROWTH OF CATTLE IN A SAFE MANNER. TRACE MINERALS SUCH AS ZINC AND MANGANESE CRITICALLY SUPPORT MANY GROWTH PROCESSES IN THE BODY, INCLUDING MUSCLE GROWTH. HOWEVER, OVERSUPPLEMENTATION OF TRACE MINERALS CAN CREATE TOXICITIES IN THE ANIMAL AND CAN RESULT IN ACCUMULATION OF METALS IN SOILS.OUR LONG TERM GOAL IS TO DEVELOP TRACE MINERAL SUPPLEMENTATION STRATEGIES THAT OPTIMIZE GROWTH OF CATTLE PRODUCED WITH MODERN HUSBANDRY PRACTICES WHILE MINIMIZING ENVIRONMENTAL IMPACT.OUR OVERARCHING HYPOTHESIS ISTHAT ZINC AND MANGANESE ARE REQUIRED TO SUPPORT ENHANCED MUSCLE GROWTH INDUCED THROUGH ADMINISTRATION OFTRENBALONE ACETATE AND ESTRADIOL.WE WILL UTILIZE A DUAL EXPERIMENTAL APPROACH, TESTING OUR HYPOTHESIS THROUGH IN VIVO (IN THE ANIMAL) AND IN VITRO (BENCHTOP LABORATORY) EXPERIMENTS TO TEST THE FOLLOWING OBJECTIVES.OBJECTIVE 1:UNDERSTAND THE ROLE OF ZINC AND MANGANESE IN PROTEIN SYNTHESIS AND MATURATION OF BOVINE SATELLITE CELL CULTURES IN THE PRESENCE OF ESTRADIOL AND/OR TRENBALONE ACETATE. OBJECTIVE 2: DETERMINE THE EFFECTS OF ZINC OR MANGANESE SUPPLEMENTATION ON GROWTH AND MARKERS OF TRACE MINERAL METABOLISM IN STEERS RECEIVING ANABOLIC IMPLANTS.WE EXPECT TO FIND THAT INCREASING ZINC SUPPLEMENTATION WILL OPTIMIZE IMPLANT INDUCED GROWTH, THROUGH IMPROVEMENTS IN MUSCLE (PROTEIN) GROWTH. WE EXPECT MANGANESE TO IMPROVE ANTIOXIDANT CAPACITY OF MUSCLE, THUS INCREASING GROWTH AS WELL.KNOWLEDGE GAINED IN THIS PROJECT WILL ALLOW STRATEGIC SUPPLEMENTATION OF ZINC AND MANGANESE TO OPTIMALLY SUPPORT GROWING MUSCLE NUTRIENT NEEDS OF BEEF CATTLE IN AN ENVIRONMENTALLY-RESPONSIBLE MANNER. BECAUSE MUSCLE NUTRITION IS LIKELY SIMILAR ACROSS SPECIES THESE RESULTS WILL BE APPLICABLE TO BOTH HUMANS AND OTHER DOMESTIC LIVESTOCK SPECIES.