| Effects of L-carnitine enriched artemia on growth and Fatty acids composition in first feeding larvae of freshwater fish were studied to offer basis to improve the culturing technology of larvae. The experimental larvae were reared in 50L tank with stocking density of 40 fish/L at 25±1℃for 21 days. The newly hatched Artemia nauplii, enriched with 4 levels (0,1,100,1000 mg/L) of L-carnitine at 25±1℃for 12 h and 24 hrespectively, were used as starter food for rearing larvae. The results indicated:in the 24 h-enriched groups, growth performances and survival of freshwater larvae might improved by L-carnitine supplementation. Growth of the common carp were significantly (P<0.05) improved by feeding lmg/L L-carnitine enriched nauplii; vitality of the common carp were improved by feeding 100 mg/L L-carnitine enriched nauplii (P<0.05); there was significantly (P<0.05) higher RNA/DNA ratio for the common carp in 1 and 100 mg/L L-carnitine enriching groups than in the control;ΣC14-24 FA and SFA content were significantly(P<0.05) lower in land 100mg/L L-carnitine enriching groups than the control group, but no significant differences (P>0.05) were observed between them;ΣC14-24 FA and SFA content were improved significantly(P<0.05) by feeding 1000mg/L L-carnitine enriched nauplii than the control group; MUFA content of larvae were decreased significantly (P<0.05) by feeding lmg/L L-carnitine enriched nauplii than the other groups; no significant differences (P>0.05) were observed on PUFA,Σn-3+Σn-6 andΣDHA+EPA content between 1mg/L L-carnitine enriching groups and the control; There was significantly (P<0.05) higher PUFA,Σn-3+Σn-6 andΣDHA+EPA content for larvae in 100 and 1000 mg/L L-carnitine enriching groups than in the control, but there was significant differences (P>0.05) were observed between them; The C/N ratio of larvae were significantly(P<0.05) lower by feeding 1 and 100mg/L L-carnitine enriched nauplii than the control and 1000mg/L L-carnitine enriching groups. In the 12 h-enriched groups,ΣC14-24 FA, SFA and MUFA content were significantly(P<0.05) lower by feeding lmg/L L-carnitine enriched nauplii than the control group; SFA and MUFA conten were improved significantly (P<0.05) by feeding 1000 mg/L L-carnitine enriched nauplii than the control group, no significant differences (P>0.05) were observed on PUFA,Σn-3+Σn-6 andΣDHA+EPA content in the treatment groups; C/N ratio were decreased significantly (P<0.05) by feeding 1000 mg/L L-carnitine enriched nauplii than 1 mg/L L-carnitine enriching group and the control (P<0.05). Linoleic acid, linolenic acid, arachidonic acid, EPA and DHA content were significantly(P<0.05) improved by feeding 1 and 100 mg/L L-carnitine enriched nauplii than the control group in the first feeding larvae of grass carp and bighead carp;ΣC14-24 FA, SFA and MUFA content of larvae were decreased significantly (P<0.05) by feeding lmg/L L-carnitine enriched nauplii than the other groups in the three species freshwater fish; there was significantly (P<0.05) higher PUFA,Σn-3+Σn-6 andΣDHA+EPA content for grass carp and bighead carp in 100 mg/L L-carnitine enriching groups than in the control; no significant differences (P>0.05) were observed on PUFA,Σn-3+Σn-6 andΣDHA+EPA content for in the first feeding larvae of common carp. Therefore, the 1 mg/L L-carnitine enriched nauplii could remarkably enhance growth performance of the first feeding larvae of common carp in the 24 h- enriched groups. The fatty acids composition and C/N ratio of common carp was improved by feeding 100mg/L L-carnitine enriched nauplii in the 24 h- enriched groups. In the 24 h- enriched groups the 100 mg/L L-carnitine enriched nauplii could remarkably enhance fatty acids composition of the first feeding larvae of grass carp and bighead carp, but there was less effect on fatty acids composition of common carp.
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