| Effects of methionine enriched Artemia nauplii on growth performance, amino acids composition, related enzyme activity and antioxidant capacity in first feeding larvae of bighead carp(Aristichthys nobilis)and common carp(Cyprinus carpio)were studied. The newly hatched nauplii were enriched with 4 levels(0,400,800,1600 mg/L) of methionine for 16 h, were used as starter food for rearing larvae for 21 days. The body length and body weight of the larvae were determined at day 7,14 and 21 respectively. The correlative parameters were determined at day 21.(1) In bighead carp, there was no significantly(P>0.05) effected on SGR and BLGR in each group at day 7 and 14 of this experiment. At day 21, there were significantly(P<0.05) higher SGR and BLGR of 400 and 800 mg/L methionine enrich group than that in the control and 1600 mg/L group. At day 7 of common carp, compared to the control group, 400, 800 and 1600 mg/L group significantly(P<0.05) improved SGR. At day 7, BLGR of 1600 mg/L group was significantly(P<0.05) higher than that of the others. At day 14 and 21, there was significantly(P<0.05) higher BLGR of 800 and 1600 mg/L methionine enrich group than that in the control and 400 mg/L group.(2) The methionine content of nauplii and larvae had significantly(P<0.05) differences among these treatments. In bighead carp, the activities of CK and γ-GT in 800 mg/L group were significantly(P<0.05) higher than the other three groups. Compared to the control and 1600 mg/L group, the results indicated that 400 and 800mg/L of methionine significantly(P<0.05) increased the activity of Na+K+-ATPase. In common carp, compared to the control, the activity of CK in 800 and 1600 mg/L group was significantly(P<0.05) increased. The activities of Na+K+-ATPase and γ-GT in 1600 mg/L group were significantly(P<0.05) higher than that in the control and 400 mg/L group. In bighead carp, there was significantly(P<0.05) higher content of total amino acids in 800 mg/L methionine enrich group than that in the control and 1600 mg/L group. The content of Lys, Arg and Cys in 400 and 800 mg/L group were significantly higher(P<0.05) than that of the others. Compared to the control and 400 mg/L group, the content of Gly and Ala in 800 mg/L were significantly(P<0.05) increased. The content of Thr in 800 mg/L group was significantly(P<0.05) higher than the other three groups. The content of Phe in 800 mg/L group was significantly(P<0.05) higher than that in the control group. In common carp, the content of total amino acids was significantly(P<0.05) increased by supplementation of 1600 mg/L methionine enrich group in this study. Compare to the control and 400 mg/L group, the content of Thr, Phe,Gly and Ala in 1600 mg/L group were significantly(P<0.05) higher. There was significant(P<0.05) high concent of Lys in 1600 mg/L group compared with the others. There were significantly(P<0.05) higher SGR and BLGR of 400 and 800mg/L methionine enrich group than that in the control and 1600 mg/L group. The content of Asp and Cys in 800 and 1600 mg/L group were significantly(P<0.05) higher than that in the control and 400mg/L group.(3) In bighead carp, there were significantly(P<0.05) higher activities of SOD, T-AOC and carnitine content in 800mg/L methionine enrich group than that of the others. The activity of CAT and GSH content in 400 and 800 mg/L group were significantly(P<0.05) higher than that in the control and 1600 mg/L group. In common carp, there was significantly(P<0.05) higher activity of SOD and GSH content in 1600mg/L group than that of the others(P<0.05); Activity of CAT and carnitine content in 800 and 1600 mg/L group were significantly(P<0.05) higher than that in the control and 400 mg/L group. Compare to the control and 400 mg/L group, supplementation of 1600 mg/L methionine enrich group, T-AOC was significantly(P<0.05) higher.In this experimental condition, the 800 mg/L methionine enriched nauplii showed the better growth performance, improved the amino acid composition and related enzyme activity, enhanced the antioxidant capacity in first feeding larvae of bighead carp. However, the 1600 mg/L methionine enriched nauplii could remarkably enhance growth performance and effectively improve the amino acid composition and related enzyme activity in first feeding larvae of bighead carp. At the same time it can improve the body’s antioxidant capacity in first feeding larvae of common carp. |
