Effect of immunopolysaccharide （yeast cell wall） on non-specific immune function in juvenile soft-shelled turtles （Pelodiscus sinensis） by oral administration

The effect of the dietary immunopolysaccharide(yeast cell wall)on non-specific immune function in juvenile soft-shelled turtle(Pelodiscus sinensis)was studied.The turtles were divided into 6 groups and were fed with feed supplemented with different ratio of yeast cell wall,that was 0 mg/kg(control group),500.0 mg/kg.B.W.(group I),1000.0 mg/kg.B.W.(groupⅡ),1500.0 mg/kg.B.W.(groupⅢ),2000.0 mg/kg.B.W.(groupⅣ)and 2500.0 mg/kg.B.W.(groupⅤ) respectively.28 days later,the turtles were blooded,and the phagocytic activityof the leucocytes,serum lysozyme activity and complement activity were monitored.The results showed that the phagocytic activityand lysozyme activity in group I,Ⅱ andⅢ were significantly higher than the control group(t-test,P(0.05)).However,there were no significant differences among groupⅣ,Ⅴ and the control group(t-test,P0.05).The highest complement activity was observed in groupⅡandⅢ,which was significantly higher than the control group(t-test,P0.05).As the complement activity was concerned,there were no significant differences between group I,Ⅳ,Ⅴ and control group(t-test,P0.05).The results demonstrate that the best supplementation ratio of the yeast cell wall in the soft-shelled turtle is about 1000.0 mg/kg.B.W,and immunosuppression in soft-shelled turtles will probably occurwhen the supplementation ratio go beyond 1500.0 mg/kg.B.W.