| 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 0.43dą0.02g 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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