THE INCREASED FEED COSTS TOGETHER WITH ENVIRONMENTAL CONCERNS ASSOCIATED WITH SWINE PRODUCTION NECESSITATE THE DEVELOPMENT OF COST-EFFECTIVE SOLUTIONS TO IMPROVE THE SWINE FEED EFFICIENCY AND DECREASE THE NUTRIENTS EXCRETION. A MODERATE REDUCTION IN DIETARY PROTEIN MAY MAKE THE DIETS MORE COST-EFFECTIVE AND PRODUCE EVEN MORE BENEFICIAL RESULTS IN TERMS OF HEALTH AND NUTRIENTS EXCRETION. HOWEVER, WHILESUPPLEMENTED WITH THE FIRST FOURLIMITING AMINO ACIDS, MODERATELY LOW PROTEIN(MLP) DIETSLEADTO POOR PERFORMANCE INPIGS. WE HYPOTHESIZE THAT SUPPLEMENTING ISOLEUCINE (ILE) AND VALINE (VAL) INDIVIDUALLY OR AS A MIXTURE TO MLP DIETS WILL IMPROVE THE GROWTH PERFORMANCE OF NURSERY PIGS IN PART BY MODULATING FEED INTAKE, GUT MICROBIAL POPULATIONS, NUTRIENTS UTILIZATION, AND METABOLIC FACTORS. THEOBJECTIVE OF THE PROPOSED RESEARCH IS TO CHARACTERIZE DIETS WITH THE OPTIMAL LEVELS OF ILE AND VAL THAT WILL IMPROVE FEED EFFICIENCY.IN 4INDEPENDENT EXPERIMENTS, THE EFFECT ILE, VAL, AND COMBINATION OF BOTH AT OR ABOVE RECOMMENDED LEVELSON GROWTH PERFORMANCE AND ENERGY BALANCE OF WEANED PIGS FED WITH MLP DIETS WILL BE ASSESSED. WE EXPECTTHAT THE GROWTH PERFORMANCE OF PIGS RECEIVING MLP DIETS WILL BE IMPROVED WHEN THEY ARE SUPPLEMENTED WITH ILE AND/OR VAL THROUGH EITHER PARTIALLY OR COMPLETELY IMPROVING FEED INTAKE,NUTRIENTS UTILIZATION, GUT MICROBIAL POPULATION, ANDBLOOD METABOLITES.IDENTIFYING THE OPTIMALLEVELS OF DIETARY ILE AND VAL WHEN SUPPLEMENTED INDIVIDUALLY OR IN COMBINATION TO ALLEVIATE THE NEGATIVE INFLUENCES OF MLP DIETS ON FEED EFFICIENCY OF NURSERY PIGS AS WELL AS UNDERSTANDING THE MECHANISMS BY WHICH THESE AMINO ACIDS PROMOTE THE PERFORMANCE OF ANIMALS MAY LEAD US TO DEVELOP MORE EFFECTIVE STRATEGIES TO ENHANCE PRODUCTIVITY, WHICH COULD HAVE MAJOR IMPLICATIONS FOR PROFITABILITY.