【正文】 reduction. Continuous enhancement of the productivity of laying hens, immune response ability is reduced gradually, in the actual production, although the contact of pathogenic microorganisms chance reduced by improving the health status of new technologies, adopt measures, but the hen is inevitably accept various stimuli, often in a normal stress a return to a normal cycle, production performance the need to maintain, increase the proportion of deposits, reduce skeletal protein, ultimately affect the performance and immune function mechanism 5, immunological stress on immune system of an Mechanisms of the immune stress on animal immune system Mechanisms of the immune stress on animal immune system is generally thought to be mediated by glucocorticoid. Adrenal cortical hormone can cause immune suppression. In addition, in the process of immune stress, neuroendocrine system activity changed obviously, which is one of the important factors lead to the change of the function of the immune system. Fan Shaoguang thinks, adrenal cortical hormone mediated stress has a concentration range, he also put under stress, through the central nervous system, the peripheral T lymphocytes produced a large protein molecules, this view may have inhibitory effects on some immune function, inhibit protein called immune, it is immunological stress caused by immunosuppressive opens up a new domain. The body mainly through the hypothalamic pituitary adrenal axis (HPA) system is involved in the regulation of stress response, glucocorticoid is an end product of HPA axis, with corticosterone, cortisol, mainly by the adrenal cortex zona fasciculata secretion, with a wide range of effects on the immune system. The way to participate in HPA axis regulation of stress response, also need to participate in the pituitary thyroid system. In the immune stress, may be increased due to adrenal cortical hormone and thyroid hormone in the body, make the body39。s physiological needs. The resulting stress leads to decrease of slow growth, reduced fecundity, productivity and product quality variation, the immunity of livestock and poultry, causing great harm to livestock and poultry production. In the modern industry production, vaccines for the prevention, control and eradication of infectious diseases of livestock play an extremely important role, immunization hand to protect the body against animal pathogens, on the other hand, as a kind of special stress factor resulting in immunological stress, some damage to the body, the damage is not only affect the growth and development and the production performance of livestock and poultry, and may cause a few animal death. 1,the stress response mechanism The mechanism of stress response is a plex process, according to the Canadian pathologist Hans Selye stress theory, from the stress state of view, can be divided into three periods: alert period (emergency reaction stage), resistance (resistancestage) and failure stage (exhaustion stage). The alert period. The body has not yet received the adaptation period, the body is early response to stressors. According to the physiological and biochemical changes of different, this period can be divided into shock and reverse shock phase. Shock phase as temperature and a decrease in blood pressure, blood concentration, inhibit the nervous system, muscle tension decreased, and then to tissue degradation, hypochloremia, hyperkalemia, gastrointestinal ulceration, body resistance is lower than the normal level. Shock is sustainable for a few minutes to 24 hours. The stress response to enter the shock