| The study was conducted to Cyprinus carpio,the effects of dietary different chromium source and different chromium level on growth performance,biochemical traits and glucose metabolism.To determine the appropriate chromium source in the carp feed and take reference for the application of chromium as feed additive.1.Study on the suitable Chromium Source in CarpA feeding trial was conducted to determine the effects of 2 mg/kg Cr2O3,2 mg/kg Chromium Picolinate(Cr-Pic),2 mg/kg Chromium Methionine(Cr-Met)on growth performance,immunity and glucose metabolism enzyme activity in carp.A total of 720 carp with initial body weight of 40.95±4.80 g were randomly divided into 4 treatment groups,each processing setting three replicates of 60 fish,the test cycle was 8 weeks.Fish fed diets with Cr2O3,Cr-Pic and Cr-Met had significantly improved weight gain and specific growth rate of carp(P<0.05),Cr-Met group was the best.Feed conversion for fish fed the diet with Cr-Met was the lowest,and had significantly lower than control group(P<0.05).There was no significant difference among the content of water,ash and crude protein between the control and chromium groups(P<0.05).Fish fed diets with Cr-Pic and Cr-Met had significhanly higher whole body crude lipid contents than control group(P<0.05).Digestive enzyme activities were significantly raised by dietary Cr-Met in carp(P<0.05).Studies have shown that immunity ability significantly increased at Cr-Met by measuring T-AOC,T-SOD,CAT,MDA,GOT,GPT and AKP in hepatopancreas(P<0.05).The serum glucose concentration in fish fed Cr-Met was significantly lower than control group(P<0.05).Significantly lower cholesterol concentration was observed in fish ded diets supplemented with Cr-Pic and Cr-Met(P<0.05).There was no significant difference of triglyceride concentration among the test groups(P<0.05).Growth hormone concentration fed the diet with Cr-Met was significantly higher than control group(P<0.05).There was no significant difference of insulin concentration between the control and chromium groups(P<0.05).Fish fed diets with Cr-Pic and Cr-Met had significhanly higher glucagon than control group(P<0.05).Liver glucose concentration with chromium groups were significantly higher than control group(P<0.05).Fish fed diets with Cr-Pic and Cr-Met had significhanlyhigher hexokinase activity than control group(P<0.05).The activities of pyruvate kinase,phosphate kinase,succinate dehydrogenase fed the diet with Cr-Met was significantly higher than control group(P<0.05).In conclusion,the optimal chromium source for carp was Cr-Met.2.Study on the suitable Cr-Met level in CarpIn order to investigate the effects of Cr-Met levels on growth performance,immunity,glucose metabolism enzyme activity and related gene expression in carp.A total of 1260 carp with initial body weight of 40.95±4.80 g were randomly divided into 7 treatment groups,each processing setting three replicates of 60 fish,the test cycle was 8 weeks.Seven purified diet were prepared with the Cr-Met respectively supplemental levels of 0(control group),0.1,0.2,0.4,0.8,1.6 and 3.2 mg/kg.Fish fed diets supplemented with 0.4-1.6 mg/kg Cr-Met had significantly higher specific weight gain and growth rate of carp(P<0.05).Feed conversion with 0.8 mg/kg Cr-Met was significantly lower than control group(P<0.05).There was no significant difference among the content of water,ash and crude protein.The content of crude lipid of whole body was significantly influenced(P<0.05).Digestive enzyme activities of carp were significantly raised by 0.4-1.6 mg/kg Cr-Met(P<0.05).The activity of SOD in Cr-Met groups were significantly raised(P<0.05).T-AOC and CAT activities were significantly raised by 0.8-1.6 mg/kg Cr-Met(P<0.05).The content of MDA reaches the lowest at the Cr-Met level of 0.4 mg/kg(P<0.05).From the perspective of immunity,AKP activities was significantly decreased at 0.4-1.6 mg/kg Cr-Met(P<0.05).GOT activities of all Cr-Met groups were significant higher than control group(P<0.05).GPT activities was significantly rised at 3.2 mg/kg Cr-Met(P<0.05).The serum glucose concentration in all Cr-Met groups were significantly lower than control group(P<0.05).Significantly lower cholesterol concentration,triglyceride concentration and LDL-C were observed in 0.4 mg/kg Cr-Met(P<0.05).The content of HDL-C was higher than other groups at 1.6 mg/kg Cr-Met.Growth hormone concentration fed the diet with 0.1-1.6 mg/kg Cr-Met were significantly higher than control group(P<0.05).There was no significant difference of insulin concentration in each Cr-Met groups(P>0.05).The content of higher glucagon was significant higher than control group at 0.8-3.2mg/kg Cr-Met(P<0.05).Glucose metabolism enzyme activity could be rised by dietary Cr-Met.Fish fed diets with 0.8-1.6 mg/kg Cr-Met had significhanly higher hexokinase and intestine kinaseactivity than control group(P<0.05).Pyruvate kinase activity could be rised at 1.6 mg/kg Cr-Met(P<0.05).Succinate dehydrogenase activity in fish fed the diet with 0.8 mg/kg Cr-Met was significantly higher than control group(P<0.05).IR,GLUT2 and HK m RNA expression of hepatopancreas could be significantly rised at 0.4-1.6 mg/kg Cr-Met(P<0.05).GLUT m RNA expression of gut was significantly rised at 0.8-1.6 mg/kg Cr-Met(P<0.05),but it is lower than that in hepatopancreas.SLGT m RNA expression was significant higher than control group(P<0.05).After hungry 48 h,Fish were fed with the dietary of control group,0.8 mg/kg Cr-Met group and 3.2 mg/kg Cr-Met group.IR,GLUT2,HK and SGLT m RNA expression levels in hepatopancreas and intestine during the refeeding after fasting 48 h were tested.As for the IR and HK m RNA expression level in hepatopancreas at 12 h after refeeding,0.8 mg/kg Cr-Met group was significantly higher than other group(P<0.05).As for the GLUT2 m RNA expression level in hepatopancreas at 6 h after refeeding,0.8 mg/kg Cr-Met group was significantly higher than other group(P<0.05).As for the GLUT2 and SGLT m RNA expression level in intestine at 12 h after refeeding,0.8 mg/kg Cr-Met group was significantly higher than other group(P <0.05).In conclusion,the suitable Cr-Met level was 0.4-1.6 mg/kg in carp. |
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