| The present study were conducted to determine the optimum dietary requirement of manganese,cobalt and selenium for juvenile cobia(Rachycentron canadum)with manganese sulfate(Mn-S),glycine manganese(Mn-Gly),manganese 2-Hydroxy-4-(methylthio)butyrate(Mn-MHA),as manganese sources,cobalt chloride(Co-C),cobalt Methionine(Co-Met)as cobalt sources,sodium selenite(Se-S),selenium methionine(Se-Met)as selenium sources and to compare the bioavailability of the different supplemental sources.The results of the present study are presented as follows.1.The basal diet designed with casein and fish meal as protein sources,corn starch as glycogen source,corn oil,fish oil and soybean lecithin as lipid sources,respectively.adding different sources and levels of manganese in the basis diet to study the growth performance,immune index and the element content in tissues of juvenile cobia.The experiment results show that: 1)there were significant difference in weight gain rate(WGR),specific growth rate(SGR),feed coefficient ratio(FCR)(P<0.05),but no survival rate(SR)in treatments(P>0.05).To some extent,dietary Mn level increased FCR.With the dose increase of Mn,the SGR and WGR increased first,then stable.Based on SGR,the biological utilization of Mn-MHA and Mn-Gly,with Mn-S as the standard were3.92 and 2.47 times.Using the broken-line model with SGR as the dependent variables,the dietary Mn requirement from Mn-S,Mn-Gly and Mn-MHA of juvenile cobia was estimated to be 15.42,11.22 and 10.50mg/kg.2)Liver Mn-SOD activity and MDA content were significant affected by dietary Mn levels and sources(P<0.05).The activities of Mn-SOD in the liver and serum were significant increased with dietary Mn,but the MDA contents in the liver and serum were decreased.Based on the activities of Mn-SOD in the liver,the biological utilization of Mn-MHA and Mn-Gly,with Mn-S as the standard were were 1.39 and 1.09 times.3)The Mn content of vertebrae and whole body significant increased with dietary Mn level.Based on the Mn content of vertebrae,the biological utilization of Mn-MHA and Mn-Gly,with Mn-S as the standard were were 1.31 and 1.22 times.2.The basal diet designed with casein and fish meal as protein sources,corn starch as glycogen source,corn oil,fish oil and soybean lecithin as lipid sources,respectively,Different the sources of cobalt and different levels of cobalt source were added to the basisof feed to study the growth performance,serum biochemical indicators and the cobalt content in tissue of juvenile cobia.The interrelated influence of cobalt and V B12 on the growth of juvenile cobia was studied by using the an addition of vitamin B12 50?g/kg basal diet containing Co 0 and 10 mg/kg.The experiment results show that: 1)The dietary Co level has a significant impact on SGR and SR(P<0.05).With the dose increase of Co,the SGR and WGR increased first,then decrease.The SGR of B12-50-Co-Met-9.60,B12-50-Co-C-9.94 and B12-50-C-0.12 groups significantly higher than that in control.To some extent,dietary Co level increased FCR.Based on SGR,the biological utilization of Co-Met,with Co-C as the standard were 1.47 times.Using quadratic polynomial regression equations,with SGR as the dependent variables,the dietary Co-Met,Co-C of juvenile cobia were estimated to be 19.40 and 17.75mg/kg.The red blood cell count(RBC),hemoglobin content(HGB)and hematokrit(HCT)were significant affected by the Co concentrations of dietary and VB12(P<0.05).With the dose increase of cobalt,the RBC,HGB and HCT increased first,then decrease.RBC,HGB and HCT of B12-50-Co-Met-9.60,B12-50-Co-C-9.94 and B12-50-C-0.12 groups significantly higher than that of control.Based on RBC,the biological utilization of Co-Met,with Co-C as the standard were 1.49 times.3)The Co concentrations of Vertebrae and whole body were significant impact by dietary Co content(P<0.05),but there were no significant difference of Co concentration in liver among treatments.Based on the Co content of vertebrae,the biological utilization of Co-Met,with Co-C as the standard were 1.12 times.3.The basal diet designed with casein and fish meal as protein sources,corn starch as glycogen cource,corn oil,fish oil and soybean lecithin as lipid sources,respectively.Different sources,levels of selenium and VE were added to the basal diet to study the growth performance,immune index and the selenium conten in tissue of juvenile cobia.The interrelated influence of Se and VE on the growth of juvenile cobia was studied by using the an VE 0 mg/kg,120mg/kg and 240mg/kg basal diet containing Se 0.3and1.2mg/kg mg/kg.The experiment results show that: 1)There were significant difference of WGR,SGR among treatments(P<0.05),but FCR and SR were not affected by Se source level(P>0.05).With increasing of Se level,the SGR and WGR increased first,then decrease.Based on SGR,the biological utilization of Se-Met,with Se-S as the standard was 1.19 times.Using the quadratic polynomial regression equations,with SGR as the dependent variables,the dietary Se-Met and Se-S of juvenile cobia was estimated to be 1.29 and 1.46mg/kg.2)The Se content and sources have significant impact on liver CAT activity and the MDA content,serum T-SOD activity(P<0.05),but there were not significant difference of liver GSH-Px,GR activity and serum GSH-Px,GR and MDA content among treatments(P>0.05).The activities of GSH-Px in the liver and serum were significant increased and the GR contents in the liver and serum were decreased with dietary Se level.The activities of GSH-Px in liver of Se-S-1.26 and Se-Met-1.33 were the highest and the activities of GR in same groups was the lowest.Based on the activities of GSH-Px and CAT in the liver,the biological utilization of Se-Met,with Se-S as the standard were 0.72 and 1.01 times.3)The Se content of vertebrae,liver and whole body significant increased with dietary Se level.Based on the Se content of whole body,the biological utilization of Se-Met,with Se-S as the standard,were 0.92 times.4)In the Se-S experiment and Se-Met experiment,results indicate that there were no significant effects of Se content and VE interaction on SGR,SR and FCR(P>0.05).SGR were greatly affected by the Se content and VE supplement levels,which increased with the dose increase of Se content and VE.Using response surface analytical method,when the VE and Se content were supplemented with levels as 94.01 and 1.18 mg/kg in the Se-S experiment and 212.53 ? 1.04 mg/kg in the Se-Met experiment,juvenile cobia abtained the best growth performance.5)In the Se-S experiment,Se interacted with VE content significantly(P<0.05)affected the liver MDA content,T-SOD and CAT activity of juvenile cobia,but not on the liver and serum GSH-Px,GR,serum T-SOD,CAT activity and MDA content(P>0.05).In the Se-Met experiment,Se interacted with VE content significantly(P<0.05)affected on the liver T-SOD activity and MDA content,but not on the serum GSH-Px,GR,T-SOD,CAT activity and MDA content(P>0.05).6)In the both S-Se experiment and Se-Met experiment,The liver and vertebra Se concentration were significantly affected by Se interacted with VE(P<0.05)but there were no significant difference of whole body Se content among treatments(P>0.05).The whole body Se concentration was significant affected by the Se contert in diet but not the VE concertration. |
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