The influence of stress of various etiologies on the body of broiler chickens

The article presents an analysis of the effects of stress of various etiologies on the body of a fast-growing bird, with an emphasis on physiological, immunological and metabolic disorders. The main stress factors, including heat, cold, light, high-density planting, fodder and immune stress, as well as their consequences for poultry health, are considered. Special attention is paid to changes in the biochemical composition of blood, mechanisms of oxidative stress, disorders of the intestinal microbiota and changes in gene expression under the influence of stressors. The work shows that heat stress leads to a significant decrease in productivity, metabolic disorders and activation of oxidative processes, which is confirmed by an increase in cortisol levels and a decrease in thyroid hormones. Cold stress causes structural damage to tissues, including the heart and intestines, as well as an imbalance of pro-inflammatory cytokines. The light regime significantly affects the stress level, which affects the ratio of heterophiles and lymphocytes. Planting density is associated with an increase in leukocytosis and a change in electrolyte balance. Lipopolysaccharide-induced immune stress (LPS) leads to significant changes in the microbial composition of the intestine and correlates with the modulation of genes related to inflammation and metabolism. The research results emphasize the need for further research in the field of stress management in poultry farming, including the development of feeding programs using modern adaptogens. The purpose of this review is to summarize current scientific data over the past 5 years on the etiology of various types of stress in intensive poultry farming, as well as to establish their effect on the body of fast-growing poultry. This study will be useful as a theoretical and fundamental basis for the development of programs to enhance the adaptive capabilities of the bird's body, including through nutritional factors.