Study On Effects Of Different Levels Of Dietary Protein And Dextrin On Growth Perfomance And Carbohydrate Metabolic Mechanism Of Ukraine Scale Carp

3×3 factorial design being used in the experiment,nine diets were formulated containing three protein levels(28%,30%,32%)and three dextrin levels(15%,20%,25%).The Ukraine scaly carp were fed for 8 weeks to measure its growth and activities of carbohydrate metabolism enzyme to study the effects of different levels of dietary protein and dextrin on the growth.Being based on growth indicators selected 30% protein level and 15% dextrin or25% dextrin level respectively,refeeding after fasting 48 h and sampled the tissue at3,6,12,24,48 h to research the effect of dextrin levels on glucokinase(GK),glucose-6-phosphatase(G6Pase)gene expression in hepatopancreas and intestinal of scales carp Ukraine.The results showed that:28% dietary protein level can improve the liver index significantly(P<0.05),relative weight gain rate,specific growth rate and protein efficiency ratio all increased obviously and food conversion ratio decreased significantly in the groups of 25% dextrin level(P<0.05);however,there was no significant interaction of proteins and dextrin on growth indicators(P>0.05).32% dietary protein significantly improved the amylase and trypsin in midgut(P<0.05),the activity of lipase in forgut was improved by 30% dietary protein(P<0.05).While 20% dietary dextrin increased the trypsin activity in hepatopancreas(P<0.05).The SOD and CAT activities in hepatopancreas of the group fed with 20% dextrin were the highest,and the MDA contents of this group was lower than that of the 25% group(P<0.05).From the point of view of metabolic enzymes,28% dietary protein level could significantly improve activity of hexokinase(HK),GK and G6 Pase in plasma(P<0.05),20% dietary dextrin could significantly increase activity of HK,pyruvate dehydrogenase(PK)and malate dehydrogenase(MDH)in hepatopancreas(P<0.05),the interaction of proteins and dextrin influenced HK,PK,MDH,GK,G6 Pase significantly.At12 h,25% dietary dextrin could significantly improve hepatopancreas GK mRNA expression levels(P<0.05),while adding 15% dextrin increased the GK mRNA expression levels in intestinal(P<0.05).25% dextrin group hepatopancreas G6 Pase mRNA expression levels reached highest at 6h,and the other groups expressed maximum at 24 h.Compared to 15%dextrin 25% dextrin could significantly improve G6 Pase mRNA expression levels at 3h and6 h after refeeding(P<0.05).In conclusion,fish fed diets with protein levels of 30% to 32% and dextrin levels of20% to 25% got the best growth performance.Adding dextrin could save the dietary protein.