This book provides a comprehensive information about the effects of different types of stressors facing poultry industry such as rearing broilers under high stocking density and heat stress. As well as, the role of probiotic to counteract the adverse effects of these stressors on productive performance, health, carcass characteristics, blood parameters, behavioral and welfare indices. The results suggest that probiotic can be used as anti-stress feed additive in addition to its efficacy as growth promoter.