| Medicinal plant endophytic fungi, a novel pharmaceutical microbial resources, could produce extracellular polysaccharide,whichcould be used as a natural feed additive for its characteristics of efficient, non-toxic, enhancing immunity, anti-bacterial, anti-virus and no residual. On the basis ofthe extracellular polysaccharideof Gynostemma endophytic fungi JY25(JY25P for short) as experimental materials, this research observed the effects of JY25 P on broilerss’ growth, intestinal immune properties in vivo tests, the proliferation of T, B lymphocyte and cytokines excretived by intestinal mucosal immune cells in vitro tests. The purpose was to explore the effect and mechanism of extracellular polysaccharide of endophytic fungi polysaccharides in broilers production, to provide a theoretical basis and basic data for practical application.Experiment 1: Effects of JY25 Pon growth performance and intestinal structure of broilers.This experiment was conducted to study the effect of JY25 P on growth performance and intestinal structure of broilerss by adding different levels of JY25 P in the diet.By measuringthe averagedaygain(ADG), average daily feed intake(ADFI), feed/gain ratio(FGR) and the villus height, crypt depth, the ratio of villus height and crypt depth(V/C), we could analysis the effect of growth performanceand themechanisms of promoting intestinal absorption of nutrients.The conclusion was that the diet with 0.4% JY25 P had significantly improvedthe average final weight by 6.40%(P<0.05) and(ADG) by 9.89%(P<0.05), reduce ADFI by 12.63%(P<0.05) and FGR by 20.50%(P<0.05), so that enhancing economic efficiency;At the same time, the diet of 0.4% JY25 P could improve villus height by 19.73%(P<0.05)and V/C by 24.08%(P<0.05)of duodenum, increase villus height by 16.03%(P<0.05)and V/C by 25.35%(P<0.05)of jejunumat the 42 days of age.Thus, the results confirmed that JY25 P may improve small intestinal structure and enhance the body’s digestion and absorption.Considering the effect of JY25 P on growth performance and intestinal structure,addingthe dosage of 0.4% JY25 Pin the diet couldbeen the preferable production.Experiment 2:Study the mechanism of JY25 P onimmunity performance inbroilers.To analysis the mechanismof JY25 P improving immunity performance, detectingthe Newcastle disease antibody titer in the serumand the content of intestinal mucosal immune factors(SIgA, IL-4, IFN-γ). The results showed that 0.6% JY25 P couldrespectively improve the Newcastle disease antibody titerby 35.77%、35.14%、25.00%、33.50% at the age of 21、28、35、42(P<0.05), enhanced the body’s specific immunity. JY25 P increased the secretion of SIgA, IL-4 and IFN-γ in intestinal mucosal(P<0.05), which observably enhanced the body’s humoral and cellular immunity, in the meantime maintained the balance of intestinal mucosal immunityandpromoted the body’s non-specific immunity. Thus,the dosage of 0.6% JY25 P had excellent performances onspecific immunity andintestinal mucosal non-specific immunity,therefore enhanced the ability of the immunity, improvedthe resistanceof disease.Experiment 3: Effects of JY25 P on T, B lymphocytes proliferation and intestinal mucosal lymphocyte factor in vitro.Detected the effect of JY25 P on the proliferation of T, B lymphocytes, which were separatedfrom cultured the lymphocytes of peripheral blood and different immune organs of broilersby the MTT colorimetricassay in vitro. Stimulating the separated intestinal Peyer lymphocytes(PPL), intestinal intraepithelial lymphocyte(IEL) and lamina propria lymphocytes(LPL) ofbroilersby adding different concentrations of JY25 Pin vitro, detected the expression of IL-2, IL-10, TNF-αin lymphocyte supernatant.The results showed that adding 80μg/mL JY25 P directly stimulated the T lymphocytes proliferation of peripheral blood, thymus and spleen by 142.23%(P<0.01), 42.05%(P<0.05), 35.09%(P<0.01) respectively, adding 80μg/mL JY25 P could increase the B lymphocytes proliferation of peripheral blood, spleenand bursa of fabriciusby 67.99%(P<0.01), 68.47%(P<0.01), 48.73%(P<0.05) respectively. This indicated that JY25 P could enhance lymphocyte proliferation. When adding 160μg/mL JY25 P,it could significantly promote the expression of lymphocyte anti-inflammatory cytokines(IL-10)(P<0.05) and inhibit the expression of inflammatory cytokines(IL-2, TNF-α)(P<0.05),thus it can be seen that JY25 P promotedthe tissue to repair, regulated the mucosal immune state, achievedthe effect of treatingand remitting to mucosal immune disorder.In conclusion, dietary supplementation of 0.4% to 0.6%JY25P could promote the growth of broilerss, improve intestinal structure and increase Newcastle disease antibody titerin serum, promote the secretion of intestinal mucosal immune factors. Not only promotedintestinal digestion and absorption of nutrients, improved economic efficiency, while enhancing the body’s specific immunity, improving the humoral immunity and cellular immunity. The experiments in vitro showed that the appropriate concentration of JY25 P could stimulate the T, B lymphocytes proliferation andadjust the intestinal mucosal immune cells to secrete cytokines,this implied JY25 P could regulate the immune status of the intestinal mucosa, enhance the intestinal immune performance and the ability to resist disease of broilers. |
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