ISSUE FOCUS 44 FEED & ADDITIVE MAGAZINE July 2022 "High ambient temperature is one of the most common stressors in commercial poultry production, resulting in reduced feed intake and body weight gain, and increased mortality. Because of their physiological state and greater metabolic activity, broilers are more susceptible to temperature-associated environmental challenges." STRESSORS IN MODERN POULTRY PRODUCTION Heat stress is of great concern in all types of poultry production. Poultry production is associated with a range of stressors including environmental, nutritional, and biological, and such stress factors inevitably influence the animal's physiology and performance with varying degrees. HEAT STRESS High ambient temperature is one of the most common stressors in commercial poultry production, resulting in reduced feed intake and body weight gain, and increased mortality. Because of their physiological state and greater metabolic activity, broilers are more susceptible to temperature-associated environmental challenges. It also causes alterations in intestinal nutrient transporters, gut permeability and function, immune response and the endocrine system including cortisol and thyroid hormones. Moreover, elevated ambient temperatures have been reported to cause undesirable changes in carcass characteristics, bone mineralization, and meat quality. Exposure to high ambient temperature elevates the level of reactive oxygen species (ROS) and causes biological and physiological disturbances in cellular functions. An uncontrolled increase in ROS level leads to free radical mediated chain reactions, which further causes lipid peroxidation and oxidative damage to proteins, DNA, and RNA. Birds respond to such conditions by reprograming several defense mechanisms including antioxidant enzymes, heatshock proteins, and cytokines to alleviate or reduce the negative effects of Heat Stress. WHEN IS CHICKEN “HEAT STRESS” A GOOD THING? Environmental and nutritional strategies are available to improve the efficiency of these defense mechanisms. Among the strategies for coping with the impact of HS in animals, dietary interventions through supplementation of several feed additives including vitamins (e.g. A, E and C) and minerals (e.g. zinc, selenium) can be utilized to improve the host's antioxidant defense mechanism. NUTRITIONAL ADJUSTMENTS UNDER HEAT STRESS IN POULTRY PRODUCTION Reza Vakili Solutions Deployment Team, Makian Phosphate, Iran & Associate Professor, Department of Animal Science, Islamic Azad University, Iran
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