Abstract
The elevated or low temperature reduces growth, egg and meat production in birds as a result of reduced feed intake and impaired intestinal development. Further, heat/cold stress affects the digestion, absorption of nutrients and impaired immune functions.
The increased respiration eliminates more CO2 that lowers the formation of HCO3 and results in thin eggshell production and higher incidence of egg breakage during heat stress. Heat stress modifies the protein/fat ratio, increases lipid peroxidation, mobilization of minerals and vitamins from tissues, results in decreased meat quality of broilers and reduced nutritive value of eggs. Heat/cold stress activates both the sympathetic nervous system to secrete catecholamines, which increase respiration and peripheral vasodilation and the hypothalamic-pituitary-adrenal (HPA) axis which releases corticotrophin-releasing hormone (CRH) from hypothalamus. The higher level of CRH stimulates the secretion of adrenocorticotrophic hormone (ACTH) from the pituitary which activates the adrenal glands to enhance release of corticosteroid which stimulates gluconeogenesis to generate energy required during heat stress. Heat stress stimulates the production of highly conserved heat shock proteins that help in protein folding and unfolding, assembly of multi protein complexes, transport and sorting of proteins into subcellular compartments, minimization of protein aggregation and protecting the cells from apoptosis.G. Krishnan ∙ C. Devaraj ∙ V. Sejian (X)
Centre for Climate Resilient Animal Adaptation Studies, ICAR- National Institute of Animal Nutrition and Physiology, Bangalore, Karnataka, India
M. V. Silpa
Institute of Animal Breeding and Genetics, Justus-Liebig-Universitat Gieβen, Gieβen, Germany
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
2023P. K. Das et al. (eds.), Textbook of Veterinary Physiology, https://doi.org/10.1007/978-981-19-9410-4_29
Graphical Abstract
Description of the graphic: High or low environmental temperature initiates various physiological, behavioural and endocrine responses to maintain the thermal homeostasis in birds. The activated sympathetic nervous system enhances the secretion of catecholamines which increases respiratory frequency and vasodilation of peripheral blood vessels. Heat/cold stress activates the HPA axis which releases CRH from the hypothalamus, and higher level of CRH stimulates the secretion of ACTH from the pituitary that enhances release of corticosteroid from adrenal glands. The increased corticosteroid favours in the gluconeogenesis and production of glucose to meet the high energy demand during heat/cold stress. Heat/cold stress increases the generation of superoxide and other ROS. The increased lipid peroxidation compromises biological membrane integrity and functions
Keywords
Birds ∙ Egg ∙ Heat stress ∙ Stress biomarker ∙
Thermoregulation
Learning Objectives
• Learning the heat/cold stress responses of birds.
• Understanding the thermoregulatory mechanism of birds.
• Studying the impact of heat/cold stress on growth, production and reproduction in birds.
29.1