| The present study was performed to investigate the effects of dietary fish oilreplacement by vegetable oils on growth performance, body composition, serumbiochemical parameters and tissue fatty acid profiles of juvenile cobia, Rachycentroncanadum. The results can be summarized as follows:1. A total of300fish (average initial body weight13g) were randomlydistributed into15floating sea cages(1.0m×1.6m×2.0m) with20fish per cage and3cages per diet. Feeding respectively with five kinds of isonitrogenous and isoenergeticdiets, which were formulated with soybean oil replacing fish oil at0%,40%,60%,80%and100%(FO,40SO,60SO,80SO,100SO). The feeding experiment lasted for80d. The results suggest that WGR of80SO group was significantly higher than thatof100SO group(P<0.05), but there were no significant difference with others(P>0.05).SR of80SO group significantly higer than that of FO and60SO groups.100SO grouphas the highest IPF. There were no significant difference of moisture, CP, CL and ashof body and muscle among treatments(P>0.05). Liver moisture of80SO was lowestthan that of FO and100SO groups(P<0.05), but there were no significant differenceamong40SO,80SO and60SO(P>0.05). Liver crude lipid of80SO was higher thanthat of FO, but there were no different among80SO and others. Serum TP, AKP, ASTand ALT were not affected by the level of soybean oil in diets. Serum TBRAS of FOwas much higer than that of other four groups(P<0.05) and others were nodifference(P>0.05). TBIL in serum of100SO was highest among treatments. CHOLin FO and40SO were higher than that of other treatments(P<0.05).∑SFA in liver ofFO and40SO significantly higher than that of other groups. Oleic acid, linoleic acid,linolenic acid and∑PUFA concent in liver were increased and the EPA, DHA,∑n-3PUFA and∑n-6PUFA concentration in liver were decreased with the levels ofsoybean oil in diet(P<0.05). n-3/n-6ratio in liver of FO was significantly higher thanthat of other treatments(P<0.05).∑SFA, EPA, DHA,∑PUFA,∑n-3PUFA, n-3/n-6 ratio in muscle significantly decreased and oleic acid, linoleic acid, linolenic acid and∑n-6PUFA significantly increased along with the soybean oil level in thediet(P<0.05).2. A total of300fish (average initial body weight13g) were randomlydistributed into15floating sea cages(1.0m×1.6m×2.0m) with20fish per cage and3cages per diet. Feeding respectively with five kinds of isonitrogenous and isoenergeticdiets, which were formulated with linseed oil replacing fish oil at0%,40%,60%,80%and100%(FO,40LO,60LO,80LO,100LO). The feeding experiment lasted for80d. The results suggest that growth performance and morphological indices were notaffected by the level of linseed oil in diet(P>0.05). There were not significantdifference of proximate composition of the whole fish, moisture, CP, CL content ofmuscle and CL in liver among treatments(P>0.05). Ash of muscle and moisture ofliver were significantly affected by graded level of linseed oil in diets(P<0.05).Among all treatments, CHOL, TG, AKP, TBIL, HDL, LDL, AST and ALT in fishserum have no significant differences(P>0.05). TBRAS in serum of60LO wassignificanty higher than that of other groups(P<0.05) and there were no significantdifference among others(P>0.05). Serum TP of60LO was significanty higher thanthat of40LO(P<0.05) but had no difference with other treatments(P>0.05).∑SFAand EPA in liver of FO was significantly higher than that of other treatments, and∑SFA in liver of40LO was significantly lower than that of FO and significantly higherthan that of80LO and100LO groups(P<0.05). Linoleic acid and linolenic acid inliver of FO were significantly lower than those of other groups(P<0.05) and therewere no difference among others(P>0.05). There was no significanlt difference ofDHA in liver among FO,40LO and60LO groups, but significantly lower than that of80LO and100LO.∑PUFA and∑n-3PUFA concent in liver increased andEPA/DHA ratio in liver decressed with the level of linseed oil in diet(P<0.05).∑n-3PUFA in liver increased with linseed oil level in diet but decrease in100LO group.n-3/n-6ratio in liver was no significant difference among40LO,60LO and80LOgroups(P>0.05), but significantly lower than that of FO and100LO(P<0.05). Therewere no significant difference of∑SFA in muscle among40LO,60LO and100LOgroups(P>0.05), but significantly lower than that of FO and significantly higher thanthat of80LO(P<0.05). Linoleic acid concent and∑n-6PUFA in muscle increasedwith the level of linseed oil but decreased at the100%replacement. Linolenic acid concent and n-3/n-6ratio in muscle significantly increases with the level of linseed oilbut the content keep stable when the proportion arrived60%and above(P<0.05). EPAcontent in muscle had the opposite trend with the linolenic acid(P<0.05). DHA inmuscle had no regular changes, FO had the maximum and80LO had the minimum(P<0.05). EPA/DHA ratio in muscle among treatments had no significant difference(P>0.05).3. A total of450fish (average initial body weight15g) were randomlydistributed into15floating sea cages(1.0m×1.6m×2.0m) with30fish per cage and3cages per diet. Feeding respectively with five kinds of isonitrogenous and isoenergeticdiets, which were formulated with soybean lecithin oil replacing fish oil at0%,40%,60%,80%and100%(FO,40SLO,60SLO,80SLO,100SLO). The feedingexperiment lasted for56d. The results suggest that growth performances, VSI, HIS,IPF, proximate composition of the whole fish, moisture and CL in muscle, moisture inliver, SOD, lysozyme, TBRAS, TP, TBIL, AKP, CHOL, TG, AST and ALT in serumwere not affected by the level of soybean lecithin oil among treatments(P>0.05).100SLO had the significant maximum of DSI(P<0.05). CP in muscle of FOsignificant lower than that of other treatments(P<0.05), and there were no significantdifference among othersc.40SLO had the maximum ash in muscle but had nosignificant difference with FO and60SLO. CL in liver of all replace groupsignificantly higher than that of FO(P<0.05), but there were no significant differenceamong replace groups(P>0.05). HDL in serum of60SLO significantly higher thanthat of40SLO(P<0.05), but had no difference with other groups. LDL in serum of40SLO and80SLO significantly higher than that of100SLO(P<0.05), and there werenot significantly different among FO,60SLO and80SLO(P>0.05).∑SFA in liver ofFO were significantly higher than that of40SLO and60SLO groups(P<0.05) andthere were no difference among replace groups(P>0.05). Linoleic acid, Linolenic acidand∑n-6PUFA concent in liver increased and∑n-3PUFA decreased with the levelof linseed oil in the diet(P<0.05), but the EPA, DHA had the opposite trend.∑PUFAin liver of FO and100SLO han no differenc (P>0.05) but significantly lower than thatof other groups(P<0.05). n-3/n-6ratio in liver of60SLO and80SLO han no differencebut higer than that of100SLO and lower than that of FO(P<0.05). There were nosignificant difference of EPA/DHA ratio in liver and∑SFA in muscle amongtreatments(P>0.05). Linoleic acid, Linolenic acid,∑PUFA and∑n-6PUFA concent in muscle increased and EPA, DHA,∑n-3PUFA and n-3/n-6ratio decreased with thelevel of soybean li oil in the diet(P<0.05). EPA/DHA ratio significantly decreasedwith the soybean lecithin oil but the value keep stable when the proportion arrive60%and above. |
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