Morphological changes in the adrenal glands of chickens under heat stress

Abstract

Heat stress as a result of hyperthermia and dehydration of the body due to natural or artificial environmental factors negatively affects the well-being of birds. Heat stress factor can lead to significant economic losses in poultry farms due to a decrease in egg production, egg fertilization, hatching and viability of young animals, morphological indicators of eggs, an increase in bird mortality during maintenance and transportation, the occurrence of immunosuppression and metabolic disorders. Pathomorphological changes in the internal organs of birds under heat stress are classified as degenerative changes, necrosis, circulatory disorders, changes in tissue fluid, growth disorders, and inflammation. The adrenal gland affects the number of functional and metabolic processes in the body of birds, its hormones ensure its resistance to heat stress. In the current global warming climate, the study of the morphology of the adrenal gland of birds due to the action of a thermal stress factor is an urgent problem of poultry farming, since its solution contributes to the scientific justification of technologies for growing, using and treating birds. The aim of the study was to identify morphological changes in the adrenal gland of white leghorn chickens aged 3 months under heat stress. Anatomical, morphometric, microscopic and statistical research methods were used in the course of the study. It was found that the indicators of absolute mass and linear dimensions of the adrenal glands of chickens under heat stress increased relative to such indicators in clinically healthy chickens. Microscopically, circulatory disorders (edema, hyperemia, hemorrhages, congestion, thrombosis) were recorded in the adrenal glands of chickens, which on the 4th day of exposure to the heat stress factor were accompanied by activation of regenerative processes (an increase in the number of fibroblasts under the capsule) and secretory activity of endocrinocytes (an increase in the size of interrenal and suprarenal cells). Intense and prolonged stress of the adrenal glands of chickens caused by heat stress led to the withdrawal of their plastic and energy resources, and as a result caused the development of adrenal deficiency on Day 8, which was observed destructive and dystrophic changes in the interrenal and supraranal cells. The obtained data can be used to develop morphofunctional diagnostic and prognostic criteria for the state of both the adrenal glands and the avian organ as a whole under heat stress. In the future of further research-to study the features of the content and localization of nucleic acids, proteins, carbohydrates, lipids in the adrenal glands of chickens under heat stress.