THIS PROJECT WORKS ON PREVENTION OR ALLEVIATION OF SOCIAL STRESS IN LAYING HENS BY DEVELOPING AN ANIMAL-FRIENDLY METHOD. SOCIAL STRESS IS A CRITICAL FACTOR AFFECTING HEN HEALTH AND WELFARE. NOTED CAUSES OF HEN ILLNESS AND DEATH ARE SOCIAL STRESS-INDUCED AGGRESSION LEADING TO INJURIOUS PECKING AND CANNIBALISM AND STRESS-INDUCED SKELETAL DAMAGE. THESE PROBLEMS CAN OCCUR IN ALL EGG PRODUCTION SYSTEMS. BEAK TRIMMING, REMOVAL OF 1/3 TO 1/2 OF THE BEAK, IS A COMMON PRACTICE USED FOR REDUCING SOCIAL STRESS AND PREVENTING INJURIOUS BEHAVIORS. HOWEVER, BEAK TRIMMING CAUSES TISSUE DAMAGE, EXPOSING BILLION OF HENS TO PAIN (ACUTE, CHRONIC OR BOTH) ANNUALLY. AN OBVIOUS SOLUTION IS TO DEVELOP ALTERNATIVE METHODS TO SAFEGUARD HENS' HEALTH AND WELFARE DURING THEIR LIFESPAN, PARTICULARLY CONSIDERING THE EGG INDUSTRY IS MOVING TO CAGE-FREE HOSING ENVIRONMENTS. WE HYPOTHESIZE DIETARY SUPPLEMENTATION OF PROBIOTICS, GOOD BACTERIA PROVIDING HEALTH BENEFITS, IS AN ALTERNATIVE METHOD TO PREVENT INJURIOUSBEHAVIOR AND SKELETAL DAMAGE BY REPAIRING STRESS-DISRUPTED FUNCTIONS OF THE INTESTINAL MICROORGANISMS. IN THIS STUDY, CHICKS FROM AN AGGRESSIVE LAYER STRAIN (TRIAL 1), A FORMER COMMERCIAL STRAIN, AND ONE OF THE MOST POPULAR EGG LAYER STRAINS IN THE UNITED STATES (TRIAL 2) WILL BE USED. THE CHICKS WILL BE ASSIGNED TO 1 OF 3 TREATMENTS: 1) NON-BEAK TRIMMED CHICKS FED A REGULAR DIET, 2) BEAK TRIMMED CHICKS FED THE REGULAR DIET, AND 3) PROBIOTIC-TREATED CHICKS (NON-BEAK TRIMMED CHICKS FED THE REGULAR DIET MIXED WITH 250 PPM OF THE PROBIOTIC). HENS WILL BE EVALUATED FOR SKELETAL AND FOOT HEALTH, FEATHER QUALITY, EGG PRODUCTION TRAITS, FEED INTAKE, CAUSES OF DEATH, BEHAVIOR, PHYSIOLOGICAL RESPONSES, AND GUT MICROORGANISM CHANGES. ECONOMIC EFFECTS WILL BE ASSESSED. THE RESULTS FROM THIS STUDY WILL PROVIDE EVIDENCE IF DIETARY PROBIOTICS REDUCE HEN SOCIAL STRESS AND IMPROVES EGG PRODUCTION. OUR SUCCESS WILL PROVIDE CONSUMERS WITH ASSURANCE THAT HEN WELFARE AND HEALTH CAN BE IMPROVED UNDER MODERN PRODUCTION SYSTEMS; AND IT WILL PROVIDE EGG PRODUCERS WITH A NEW INSIGHT FOR DEVELOPING GUIDELINES AND PRACTICES.