Author:
DEEP CHAND VASHISHTHA -M.Sc , MBA
NSM- Bioncia International Pvt Ltd

Stress comes in many forms and seems to affect the performance of birds. The term “stress” is used to describe the detrimental effect of variety of factors on the health and performance of poultry (Rosales, 1994) Or “Stress is the nonspecific response of the body to any demand”, whereas stressor can be defined as “an agent that produces stress at any time”. Therefore, stress represents the reaction of the animal organism (i.e., a biological response) to stimuli that disturb its normal physiological equilibrium or homeostasis (Selye, 1976). The commercial high yielding breeds are more susceptible to stress and diseases. Stress represents the reaction of the animal organism (i.e., a biological response) to stimuli that disturb its normal physiological equilibrium or homeostasis. The importance of animal responses to environmental challenges applies to all species. However, poultry seems to be particularly sensitive to temperature-associated environmental challenges, especially heat stress. Understanding and controlling environmental conditions is crucial to successful poultry production and welfare. Heat Stress not only causes suffering and death in the birds, but also results in reduced or lost production that adversely affects the profit from the enterprise.

Heat stress or any type of Stress have side effect on Vital organs heart, brain, kidneys, liver, and lungs.
Heat Stress adverse effects on liver
The liver is pivotal organ of metabolic activity, which performs essential cellular functions containing the balance of energy metabolism, biosynthesis of vitamins and minerals, and ammonia detoxification (Schliess et al., 2014). Elevated blood flow transfers from the hepato-splanchnic region to respiratory muscles and superficial body tissues to accelerate heat dissipation and decrease body temperature under heat stress, therefore, liver is more sensitive to heat stress (Hai et al., 2006; Crandall et al., 2008). It has been reported that heat stress caused liver fat accumulation and inflammation, and impaired liver function in broiler.

Heat stress adverse effects on respiratory system
Heat stress can cause damage to the lung tissue of broiler chickens by disrupting the integrity of the blood-air barrier and increasing permeability diseases can cause different degrees of lung damage Mammals mainly rely on sweat glands to dissipate heat and maintain body temperature balance (Yahav, 2015), but poultry lack sweat glands, so they primarily dissipate heat through respiration when the temperature is too high (Bell et al., 2001). High-frequency breathing leads to increased susceptibility of lung tissue damage in a heat stress environment. Damage to the blood-air barrier can lead to increased lung permeability, impaired oxygen and carbon dioxide exchange function, and induce respiratory difficulties (Wang et al., 2020), further leading to various lung diseases such as tuberculosis and pulmonary inflammation (Research has shown that heat stress causes lung injury and results in the upregulation of various proinflammatory cytokines, including tumor necrosis factor.

Conclusion
High ambient temperature has emerged as a major constraint for the future development of the poultry industry, especially in the tropics and subtropics. The scarcity of resources coupled with harsh environmental conditions is the most crucial predicaments in the way to rationalize optimum production of broiler. Heat stress disturbs the physiological biochemistry of the broiler which ultimately reduces feed intake and feed efficiency which ultimately results in reduced performance and productivity. Under hot environmental conditions, feed utilization is disturbed by the deposition of fat and oxidative stress. In addition, changes in blood cells, acid-base balance, immune response, liver health, and antioxidant status are some of the major dynamics altered by heat stress.

Alleviating the Adverse Effects of Heat Stress is mandatory to achieve Production & performance poultry Business.