| Vitamin D3(VD3) was initially recognized a hormone associated with calcium and phosphorus homeostasis, but recently was found playing a role in immune system as well. As it can regulate the differentiation,proliferation of a variety of cells,and can regulate the immune function of animal.However, the studies of effects of VD on the immune system mainly focus on a cellular level, and it is remained to know how VD regulates the immune system in vivo. The purpose of the study is to investigate the effect of dietary added VD on the expression of the cytokines and the growth performance of Taihe silky chickens. The immune organ index of spleen, thurmus and bursa of fabricius were calculated and the relative expression of IL-1β, IL-6, IFN-y and TNF-a in those tissues were detected by qPCR. ELISA was used to determine the contents of serum 25(OH)D3, IL-2, IFN-y and IgG. Results were listed as follow:1.VD3 can significantly improve the expression of VDR (VD receptor) gene either in spleen, thurmus and bursa of fabricius of chicken, and shows a positive linear correlation to the level of dietary supplemented VD3.2. It differs in regulating the expression of IL-1β, IL-6, IFN-y and TNF-a among tissues by VD3, and the difference may be associated with the expressive abundance of these genes.3. IL-6 and IFN-y genes were down-regulated in spleen, thurmus and bursa of fabricius, IL-1β and TNF-a genes were down-regulated in thurmus. VD3 has divergent effects on the expression of inflammatory cytokines in chicken lymphoid tissues.4. VD3 shows a positive effect on improving the BW (Body weight) and feed conversion ratio.3,800 to 4,600 IU/kg supplemental VD3 resulted in better BW and feed efficiency in Silky Fowls.5. Chicken serum 25(OH)D3 concentrations increased with dietary VD3 levels.6. VD3 has an immunomodulatory effect in chickens fed high dietary VD3 levels by decreasing some serum cytokines concentrations at 84 d. |
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