Effect Of Yeast Cell Wall On The Performance And Immune Function On Status Of Immunosuppression In Broilers

Immune suppression of broilers occur because of stress, nutition and toxicologcal cetera factors in broiler production, which reduce broiler preformance, even produce immunosuppressive diseases. The utility way of precaution immunosuppression is to add immune enhancers in the broiler diet. The aim of the present study is to examine the effects of adding yeast cell wall on the performance traits of broilers, and the effects of adding yeast cell wall on immune function of broilers in normal state and in immunological inhibition state, and to provide theory evidences for management in immunological inhibition disease of broilers.This present experiments are divided into two parts, the experiments investigates the effect of yeast cell wall on performance in broilers, the second experiments investigates the effect of yeast cell wall on inmune function on immunosuppession status in broilers.The aims of the first experiment are to determinate the effects of adding yeast cell wall on the performance and immune response of broilers. 108 6-day-old Avian broiler chicks were divided into three groups fed with corn-soybean meal basal diet, and the basal diet added with 0.1%, 0.3% yeast cell wall respectively, to determine the effects of yeast cell wall. The results showed that adding 0.3% yeast cell wall to diet significantly increased 22-42 days daily gain of broiler(P<0.05), improved 5-42 days conversion rates, reduced broiler mortality. Added 0.3% yeast cell wall in 5-42 days broiler diets has no influence of the spleen weight and relative weight, but has the trend to increase weight of bursa andsignificantly increased the relative weight of fabricius (P<0.05), extreme significantly enhanced the thymus weight and the relative weight of thymus(P<0.01). In conclusion, adding yeast cell wall on corn-soybean meal basal diet can increase the growth performance and immune function in broilers.The objective of the second experiment was to test the effects of yeast cell wall on immune function and the resistance of immunosuppression by determination of the immune organ index, histology manifestation, transformation efficiency of blood lymphocytes and the express mRNA abundance of cytokine. One hundred and eight 5-day-old broiler chicks were randomly divided into 6 groups: basal diet, basal diet+0.1% yeast cell wall, basal diet+0.3% yeast cell wall, basal diet+ cyclosporine A, basal diet+ cyclosporine A+0.1% yeast cell wall, basal diet+ cyclosporine A+0.3% yeast cell wall, the experiment lasted for 38 days. The results showed that (1) yeast cell wall improved the weight of spleen and bursa of fabricius; cyclosporine A have no effect on the weight of spleen, bursa of fabricius and thymus; (2) the splenic cord lymphocyte were increased and periarterial lymphatic sheath were improved when added yeast cell wall. And cyclosporine A treatment decreased the splenic cord lymphocyte, but yeast cell wall supplement may release this inhibition. (3) transformation efficiency of T-lymphocyte were significantly increased when added yeast cell wall; and transformation efficiency of T-lymphocyte were great significantly decreased in the cyclosporine A treatment group, but yeast cell wall make the immunosuppression in the cyclosporine A treatment group to recover normal level.(4) the level of expression of IL-1βand IL-6 mRNA in spleen were enhanced in the yeast cell wall treatment group; the level of expression of IL-6 mRNA in spleen were depressed, but had no effect on the expression of IL-1βmRNA in spleen in the cyclosporine A treatment group and yeast cell wall had relieved this immunosuppression. These results indicate that yeast cell wall have the ability to improve the immune function of broiler chicks, and cyclosporine A have a depressant effect in immune function of broiler chicks, and yeast cell wall may release this inhibition effect.