Attenuation Of Cyclophosphamide Induced Immunosupression By Vitamin E In Laying Hens

The modulation of dietary levels of vitamin E fed to cyclophosphamide immunosuppressed laying hens were studied. 270 Nick Red laying hens were randomly divided into 5 groups; each group had 3 replications with 18 birds. Laying hens from groupⅢ,ⅣandⅤ(birds treated with vitamin E) were fed diets supplemented with 50, 100 and 200 mg/kg vitamin E, respectively, whereas groupⅠandⅡreceived only the corn-soybean meal basal diets with 44.59 mg/kg of vitamin E. Laying hens from groupⅡ-Ⅳ(birds challenged with cyclophosphamide) were injected in the thigh muscle with cyclophosphamide at 80 mg/kg body weight for 3 days, and groupⅠ(control group) were injected with the same amount of sterile saline. Birds were fed for 35 d.The results showed that:(1) Cyclophosphamide challenge significantly decreased laying rate, average egg weight and average feed intake of laying hens(P<0.05), increased break egg rate(P<0.05). Supplemental vitamin E significantly increased laying rate, average egg weight and average feed intake in cyclophosphamide immunosuppressed laying hen(sP<0.05), reduced feed-egg ratio and break egg rate(P<0.05). Birds given 50, 100 mg/kg supplemental vitamin E had better performance than those given 200 mg/kg. The performances for added vitamin E group were lower(P<0.05) compared to the control group without break egg rate.(2) Cyclophosphamide administration significantly decreased energy, CP, EE, Ca and P apparent digestibility of laying hens(P<0.05). Energy, EE and P apparent digestibility in immunosuppressed laying hens fed diets with supplemental vitamin E were higher than those fed diets without supplemental vitamin E(P<0.05). The nutrient digestibility did not differ among different levels of vitamin E supplementation(P>0.05).(3) Cyclophosphamide administration significantly reduced egg shell thickness, egg shell strength and haugh unit of laying hens(P<0.05), without egg shape index and yolk color. Diet added 50 mg/kg of vitamin E significantly elevated egg shell thickness, egg shell strength and haugh unit of hens under immunosuppression(P<0.05), and there was not significant difference compared to control group(P>0.05).(4) Cyclophosphamide treatment significantly reduced EE in egg(P<0.05), tended to reduce DM, CP and crude ash(P>0.05). Diet added 50 mg/kg of vitamin E significantly attenuated toxicity of Cyclophosphamide(P<0.05).(5) Cyclophosphamide treatment significantly reduced spleen and thymus relative weight, serum antibody titers of H5-AI, H9-AI and ND, complement C3 concentration and lysozyme activity(P<0.05), but serum IgG level was not significantly affected(P>0.05). Immune function were greater in immunosuppressed birds fed 50 mg/kg vitamin E supplementation than those fed 0, 100 and 200 mg/kg vitamin E(P<0.05).(6) Cyclophosphamide administration depressed plasma GSH-Px and SOD activities significantly(P<0.05), elevated MDA level significantly(P<0.05) Birds treated with cyclophosphamide had the highest plasma GSH-Px activity when 100 mg/kg vitamin E was added to the basal diet, had the highest SOD activity and the least MDA concentration at 50 mg/kg supplemental vitamin E, and further additions had negative effect(P<0.05).(7) In laying hens treated with Cyclophosphamide, there were significantly lower plasma PGE2,IL-1,IL-6 and TNF-αlevels compared with that in the saline-treated control hens. Birds treated with Cyclophosphamide fed diets with supplemental 100, 200 mg vitamin E /kg had greater plasma PGE2,IL-1,IL-6 and TNF-αlevels(P<0.05).Conclusion, (1) Immunosuppression significantly depressed performance, nutrient apparent digestibility, egg quality, immune function, antioxidant ability, plasma PGE2 and cytokine levels in laying hens. (2) 50 mg vitamin E /kg of diet supplementation significantly attenuated immunosuppressive effect of cyclophosphamide challenge in laying hens, through changed PGE2 and cytokine secretion, elevated antioxidant ability and immune function.