| In order to reduce or replace the use of antibiotics and chemical drugs in aquaculture,In this thesis,the hybrid grouper(E.fuscoguttatus ? × E.lanceolatus?)as the research object.The probiotics of bacillus,photosynthetic bacteria and Clostridium butyricum,were used and added in the hybrid grouper food to explore the fish growth,the influence of nonspecific immunity and disease resistance.As the following four aspects.1: The present study was conducted to investigate the effects of dietary probiotics supplementation on growth performance,immune and antioxidant abilities of hybrid grouper(E.fuscoguttatus ? × E.lanceolatus ?).Five hundred and forty fishes were randomly allotted to six groups.A basal diet was supplemented with bacillus at 0.1%,0.5% feed and with photosynthetic bacteria at 1%,5% feed,and then increase the control group and emulsified oil group.Four probiotics diet groups were configured to numbers for Diet 1,Diet 2,Diet 3,Diet 4 respectively.After feeding for 60 days,compared with control group and emulsified oils group,the body weight,weight gain rate of Diet 1 and Diet 4 group increased significantly,significantly reduce feed conversion ratio(P<0.05),the body weight,weight gain rate of Diet 2 and Diet 3 group is very significantly increased(P<0.01),very significantly reduce feed conversion ratio,the four probiotics adding groups of body length were increased significantly(P<0.05).Hepatosmatic index,viscerosomatic index,condition factor and survival rate have no significance(P>0.05).Compared with control group and emulsified oil group,the activities of serum total protein,superoxide dismutase,alkaline phosphatase,lysozyme of the probiotics diet groups increased,Diet 2 group increased significantly(P<0.05).The activities of hepatic antioxidant status(total antioxidant capacity,catalase,reduced glutathione)of the probiotics diet groups increased,Diet 2 group increased significantly.Diet 2 group of the malondialdehyde reduced significantly from those of the control group or emulsified oil group(P<0.05).After challenge with Vibrio harveyi,it can significantly improve the immuneprotection rate of the probiotics diet group.These results indicated that dietary bacillus and photosynthetic bacteria could enhance the growth performance,significantly improve the immune,antioxidant ability.2: A trial was conducted to determine the effects of dietary bacillus and photosynthetic bacteria on body composition,the intestinal digestive enzymes and structure of the organization in hybrid grouper(E.fuscoguttatus ? × E.lanceolatus?).The results showed that:(1)Crude protein and crude fat decreased significantly as dietary probiotics(P<0.05),Crude ash were not statistically different(P>0.05).(2)The intestinal trypsin and amylase activity decreased significantly as dietary probiotics(P<0.05),the lipase activity were not statistically different(P>0.05).(3)In the intestinal villus height of foregut,Compared with emulsified oil group,Diet 2group and Diet 3 group increased significantly(P<0.05),Diet 2 group increased significantly in the intestinal villus height of midgut(P<0.05),the muscle layer thickness and serous layer have no significance(P>0.05).(4)Probiotics can change the color of the fish liver to some extent,reduce fat liver cell necrosis and cavitation.(5)Compared with control group and emulsified oils group,The number of head kidney lymphocytes and melano-macrophage increased significantly(P<0.05),total head kidney cells and granulocyte have no significance(P>0.05).These results indicated that dietary bacillus and photosynthetic bacteria could enhance the fish intestinal digestive enzymes and improve the intestines,liver and kidney structure of fish,and the then improve fish immunity.3: The present study was conducted to investigate the effects of dietary Clostridium butyricum supplementation on growth performance,immune and antioxidant abilities of hybrid grouper(E.fuscoguttatus ? × E.lanceolatus ?).Five hundred and forty fishes were randomly allotted to six groups.A basal diet was supplemented with Clostridium butyricum at 0.1%,0.2%,0.4%,0.6%,0.8%,and were configured to numbers for Diet 5,Diet 6,Diet 7,Diet 8,Diet 9 respectively,a basal diet as control group.After feeding for 60 days,Significantly maximum weight,weight gain,specific growth rate,condition factor and viscerosomatic index wereobserved in treatment with Diet 7 group supplement,Significantly minimum feed conversion ratio(P<0.05).Body length,total length,survival rate and hepatosomatic index were not significantly different among treatments.Compared with control group,Diet 7 groups showed significant increase in lysozyme,albumin and globulin activity,but decrease in alanine aminotransferase and aspartate aminotransferase activities(P<0.05).Increased total protein and plasma alkaline phosphatase activity were also noticed in Diet 7,Diet 8 group(P<0.05).The activities of antioxidant status(total antioxidant capacity,catalase,reduced glutathione)of the Clostridium butyricum diet groups increased,and the malondialdehyde reduced significantly from those of the control group(P<0.05).These results indicated that dietary Clostridium butyricum could enhance the growth performance,significantly improve the immune,serum and hepatic antioxidant ability.4: After feeding for 60 days,extract each fish total RNA of the hepatic,kidney and spleen head,and analyze the relative level of hepatic,kidney and spleen HSP70 mRNA.10 fish per tank were exposed to challenge with Vibrio harveyi,and investigate its resistance to infection by Vibrio harveyi.The experimental results showed that,compared with control group,the relative level of hepatic,kidney and spleen HSP70 mRNA in fish fed Clostridium butyricum at Diet 3 group were significantly increased(P<0.05).After challenge with Vibrio harveyi,The cumulative mortality of the Diet 6?Diet 7?Diet 8 and Diet 9 group increased from those of the control group(P<0.05).These results indicated that dietary Clostridium butyricum could enhance the relative level of hepatic,kidney and spleen HSP70 mRNA,and its resistance to infection by Vibrio harveyi.The results above,that is added in the food,photosynthetic bacteria,bacillus and clostridium butyrium can promote the growth of fish,improve the immunity and disease resistance of hybrid grouper,which can effectively reduce and replace the use of antibiotics and chemical drugs. |
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