›› 2018, Vol. 45 ›› Issue (1): 263-270.doi: 10.16431/j.cnki.1671-7236.2018.01.034

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Effects and Mechanism of Heat Stress on Physiological and Immune System in Dariy Cows

LIU Jiali1, DOU Jinhuan1, HU Lirong2, XU Qing2, WANG Yachun1   

  1. 1. College of Animal Science and Technology, China Agricultural University, Beijing 100193, China;
    2. Institute of Life Sciences and Bioengineering, Beijing Jiaotong University Beijing 100044, China
  • Received:2017-05-31 Online:2018-01-20 Published:2018-01-20

Abstract:

Heat stress syndrome of dairy cows refers to the non-specific defense response of dairy cattle induced by stimulation of high temperature which exceeding the body temperature regulation zone.While suffering the heat stress, dairy cows will activate the mechanism of hypothalamus-pituitary-adrenal axis and change the body's neuroendocrine regulation network,causing cortisol and some other hormones levels change.All of these procession synergized in the body to reduce the influence of heat stress;In addition, after heat stress,the feed intake and digestibility of dairy cows are generally reduced,and result the body is under nutrition and in a negative state of energy balance.So the cow need to increase the body glucose,fat and protein metabolism to provide more energy to relieving heat stress.However,severe heat stress will lead to dairy cows metabolic disorder and immune system damage,then leads to a decrease of digestibility,milk production, reproduction efficiency,and increases the risk of disease susceptibility, finally it takes an negative effect on economic benefits of dairy cow production and huge economic losses in livestock husbandry.At present,most studies in dairy cows heat stress are focused on milk production and reproductive performance,while few reports on physiological and immune function of dairy cows.In current paper,the secretion and regulation of cortisol,the disorder of the three metabolic processes and the expression and secretion of immune cells and cytokines were talked about in dairy cows heat stress. The aim of the paper was to provide theoretical basis for prevention and control,diagnosis and treatment of heat stress syndrome in dairy cow by understanding the effects of heat stress on the physiological status and immune function.

Key words: heat stress; dairy cows; cortisol; metabolism; immune

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