The Study Of Astragalus Polysaccharide On The Small Intestinal Mucosal Immunity Of Chicken

The early period chicken hatched, is the key to the chicken alive,internal organs and immune system are not yet mature, and maternal antibodies is very limited. How to improve the immune function and resistance to pathogen invasion are particularly important at the early period. APS has enhanced immune function, can promote the development of immune organs and cells proliferation. Select a suitable stage to oral immune APS, maximum point increase immune function and reduce the disease, are the design purpose of the experiment.The experiment to select 120 one day HY-line brown chicks, randomly divided into 6groups(A,B,C groups as experimental groups,D,E,F groups as control groups).Chicks of group A orally immunized APS at 1-6d. Chicks of group D were administered saline at 1-6d. Chicks of group B orally immunized APS at 4-9d. Chicks of group E were administered saline at 4-9d.Chicks of group C orally immunized APS at 7-12 d. Chicks of group F were administered saline at 7-12 d. APS at a dosage of 5mg/mL. Each group were oral administratied 0.5mL dosage at the same time every morning. In the age of 3 and 7 day age, via ocular-nasal routes dropped into a plume / 0.1mL NDV LaSota-vaccine solution at all groups, respectively.After oral immunization, at the day of 1,4,7,10 collected samples: Weighed the body weight, speen and bursa fabricius, then the index numbers of speen and bursa fabricius were calculated; Small intestine slice, HE staining to observe morphological changes; Used SP immunohistochemical method staining to analyze the changes of IgA+ positive cells in chicken intestinal tract; Collected blood and jejunum washings. An indirect ELISA assay was established to detect NDV specific antibody IgA. To study the effect of APS on intestinal mucosal immune function in chicken. The result show that:1. The villus height and V/C radio in chickens of experiment groups were significantly improved. It indicated that APS could promote the growth of chicken and strengthen the function of small intestine absorption;2. The number of gut mucosa IgA+cells in chickens of experiment groups were significantly enhanced. The results showed that APS could enhance the capacity of small intestine disease resistance and improve the small intestinal immune function;3. APS could significantly enhance the index numbers of immune organ, and promote chicken blood and intestinal mucosa to secrete more NDV specific IgA antibody. It indicated that the APS could promote immune organ development, enhance the specific humoral immunity, andenhance the chicken systemic and intestinal local mucosal immune responses at the same time,which improve the intestinal mucosal immune function;Oral immunization APS could enhance gut mucosal immune function of chicken.The results of three experimental groups were higher than their corresponding control groups. Oral immunization APS in the different stages there are differences in immune enhancement. 4-9d and 7-12 d immune groups were significantly higher than the 1-6d immune group(p<0.05 or p<0.01), and 7-12 d immunization effected best.In summary, this study starts from the intestinal mucosal morphology, IgA+ cell number and distribution, the index numbers of speen and bursa fabricius and IgA antibody level, it studies the effect of APS on intestinal mucosal immune function of chicken, which provide a theoretical basis for poultry development, timely immunization and disease prevention.