| The objective of this study was to evaluate the effect of dietary supplementation of a probiotic bacterium,Bacillus subtilis,on the growth,immune function,antioxidant capacity and poison attack survival of juvenile GIFT.Tilapia with an average initial weight of 0.43d±0.02g were randomly assigned to seven groups with three replicates.The seven groups were fed diets supplemented weith B.subtilis at doses of 0%,0.03%,0.06%,0.09%,0.12%,0.15%,0.18%feed respectively.After 56 days of culture,the results suggested:first,tilapia fed with B.subtilis at dose of 0.03%-0.18%showed better weight gain rate,specific growth rate and feed coefficient than the control group,but,no significant difference with control group(P>0.05).Sceond,tilapia fed with B.subtilis at dose of 0.12%-0.18%showed that the spleen index,and the lysozyme activity,complement 3,alkaline phosphatase activity in blood serum were significantly higher(P<0.05)than contorl group,the glutamic-oxalacetic transaminease activity and glutamic-pyruvic transaminase activity in blood serum were significantly lower(P<0.05)than contorl group.However,there was no significant difference(P>0.05)in liver index and total protein,albumin and globulin level across all the groups.Third,tilapia fed withB.subtilis at dose of 0.09%-0.18%showed that total superoxide dismutase,catalase and total antioxidant capacity activity in blood serum were significantly higher(P<0.05)than contorl group,and malonaldehyde level was significantly lower(P<0.05)than contorl group.Fourth,cumulative survival rate for 168 hours in the groups that fed with B.subtilis at dose of 0.09%-0.18%were significantly increased(P<0.05)as compared with the control group.These results indicated that the probiotic B.subtilis could promote the growth to a certanin extent,and the B.subtilis could significantly promote the immunity function and antioxidation capacity.The appropriate dose of B.subtilis in the diet was 0.12%-0.18%(2.82×1010～4.23×1O10cfu/kg). |
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