| Hucho taimen is a ferocious carnivorous fish, growing fast, and easily domesticated. It’s as a good cold water aquaculture object, the meat is delicious, and nutrition is rich. At present, Hucho taimen has been domesticated and bred successfully in Heilongjiang, Liaoning, Shandong, Xinjiang more than a dozen of provinces. Some nutrients requirement of Hucho taimen has been reported, but the research is not sufficient for the production, myo-inositol(MI) requirement of Hucho taimen has not been reported.An8-week feeding trial was conducted to estimate the dietary requirement of inositol for Hucho taimen with different lipid levels. Myo-inositol was supplemented at0、100、200、400、600、800mg/kg diet in the basic diet with two lipid levels(7.2%and12.4%, in addition, make a7.2%lipid level and5000mg MI/kg diet). Each diet was fed to triplicate groups of Hucho taimen (mean initial weight2.83±0.44g), each group has30fish, and then analyzed the growth performance, feed utilization, digestive enzyme activity and indices of antioxidant. We can obtain optimal level of dietary myo-inositol with two lipid levels. Thereby make a contribution to efficient, environmental feed, and reduce the cost, better for mass production, achieve the best condition for breeding. Provide basic date and theoretical basis for further research for the feeding of Hucho taimen.The results showed that:The interaction between lipid level and inositol concentration affected weight gain and hepatosomatic index (HIS) significantly (P<0.05). With the same lipid level, growth performance increased with the increasing of inositol concentration. With7.2%lipid level, weight gain of Hucho taimen fed the diet supplemented with499.8mg MI/kg diet was highest, and significantly (P<0.05) higher than Hucho taimen fed diets supplemented with≦299.8mg MI/kg diet. Feed conversion ration was lowest in Hucho taimen fed the diet with499.8mg MI/kg, significantly (P<0.05) lower than Hucho taimen fed with≦299.8mg MI/kg diet and5099.8mg MI/kg diet, and feed conversion ration was highest in fish fed diet with5099.8mg MI/kg diet. Specific growth rate of Hucho taimen fed diets with499.8～899.8mg MI/kg diet was significantly (P<0.05) higher than those fed diets with≦299.8mg MI/kg diet and5099.8mg MI/kg diet. Viscerosomatic index (VSI) of Hucho taimen fed diets with5099.8mg MI/kg diet was lowest. With12.4%lipid level, Hucho taimen fed diets supplemented with328-528mg Ml/kg diet had significantly (P<0.05) greater weight gain than fed other diets. Feed conversion ration was lowest and specific growth rate was highest in Hucho taimen fed the diet with328mg MI/kg. Condition factor of Hucho taimen fed328mg MI/kg diet was significantly (P<0.05)lower than any other groups.By broken-line regression we obtained that with7.2%lipid level the requirement of myo-inositol for highest weight gain of Hucho taimen is535.8mg/kg diet, and the requirement of myo-inositol was503mg/kg diet with12.4%lipid level.The graded inositol levels in diets significantly affected amylase and lipase activity in liver, and the interaction between lipid level and inositol concentration significantly affected lipase activity in liver(P<0.05). The activity of lipase increased first and then decreased with the increasing of dietary inositol concentration. Lipase activity in liver of Hucho taimen fed299.8mg MI/kg diets was significantly higher than fed the diet with99.8mg/kg diet. Supplementation of dietary inositol affected digestive enzyme activity in pyloric caeca of Hucho taimen significantly (P<0.05). Amylase activity in pyloric caeca of Hucho taimen fed499.8、699.8mg MI/kg diet was significantly (P<0.05)higher than diets with99.8、199.8mg MI/kg diet with7.2%lipid level. Amylase activity in pyloric caeca of fish fed328～728mg MI/kg diet was significantly (P<0.05) higher than diet with128mg MI/kg diet with12.4%lipid level. Different lipid level and dietary inositol concentration all affected lipase activity in pyloric caeca of Hucho taimen significantly (P<0.05). Lipase activity was higher with high lipid level, and the activity of lipase in pyloric caeca increased with the increasing of dietary inositol concentration within a certain range. Supplementation of dietary inositol affected AKP in pyloric caeca of Hucho taimen, with7.2%lipid level, the group fed the diet with499.8mg MI/kg diet has the highest activity of AKP. Different lipid level affected protease and Na+, K+-ATPase activity in intestine of Hucho taimen significantly (P<0.05). With7.2%lipid level, protease and Na+,K+-ATPase activity were significantly (P<0.05) higher than with12.4%lipid level. Dietary inositol concentration significantly affected digestive enzyme activity in intestine of Hucho taimen. With7.2%lipid level, protease activity in intestine of Hucho taimen fed diets with199.8～499.8mg MI/kg diet significantly (P<0.05) higher than the group with99.8mg MI/kg diet. With12.4%lipid level, groups fed diets with528,728mg MI/kg diet have significantly (P<0.05) higher protease activity in intestine of Hucho taimen than fed the 128mg MI/kg diet. The interaction between lipid level and inositol concentration significantly affected AKP and Na+, K+-ATPase. With7.2%lipid level, AKP in intestine of Hucho taimen fed the diet supplemented with499.8～899.9mg MI/kg diet were significantly (P<0.05) higher than the group with99.8mg MI/kg diet. With12.4%lipid level, AKP and Na+, K+-ATPase in intestine of fish fed the diet with528mg MI/kg diet were significantly (P<0.05)higher than the diet with128mg MI/kg diet.Dietary inositol concentration affected SOD significantly, with the increase of concentration of myo-inositol, antioxidant capacity enhanced. With7.2%lipid level SOD of Hucho taimen fed899.8mg MI/kg diet was significantly (P<0.05) higher than the group with99.8mg MI/kg diet. With12.4%lipid level SOD of fish fed728mg MI/kg diet was significantly (P<0.05) higher than fed the diet with128mg MI/kg diet.The interaction between lipid level and inositol concentration affected MDA in liver significantly (P<0.05). With7.2%lipid level, the concentration of MDA of Hucho taimen fed the diet with499.8mg MI/kg diet was significantly (P<0.05) lower than those fed the diet with99.8and199.8mg MI/kg basal diet. The concentration of MDA of Hucho taimen was fed the diet with128mg MI/kg diet was significantly (P<0.05) higher than other groups with12.4%lipid level.In conclusion:1) With the increasing of inositol concentration, growth performance, digestive enzyme activity and antioxidant capacity enhanced with the same lipid level.2) The diet without and excessively adding myo-inositol all reduced growth performance, digestive enzyme activity and antioxidant capacity with two lipid levels.3) The optimum level of dietary myo-inositol was535.8mg/kg diet with7.2%lipid level for Hucho taimen.4) The requriement of dietary myo-inositol is503mg/kg diet with12.4%lipid level for Hucho taimen. |
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