Effects of Isaria cicadae on growth and metabolism of juvenile Larimichthys crocea
To investigate the effects of Isaria cicadae supplementation on growth performance,antioxidant capacity,body color,meat quality and intestinal metabolism of juvenile large yellow croaker(Larimichthys crocea),juvenile fish with an initial body weight of(16.50±1.10)g were randomly divided into four groups for study.Fish were fed basal diets supplemented with 0%(IC0 group,the control),1%(IC1 group),3%(IC3 group)and 5%(IC5 group)of I.cicadae,respectively,and the experiment lasted for 56 days.The results showed as follows:(1)There was no significant difference in survival between the control and experimental groups(P>0.05),but the weight gain rate(WGR)and specific growth rate(SGR)were significantly higher in four experimental groups(P<0.05).(2)There was no significant difference in activities of MDA,CAT and GSH-Px in serum between the experimental and control groups(P>0.05).(3)There was no significant difference in the L∗ value(brightness value)and a∗ value(redness value)of the abdominal body color between groups(P<0.05),but the b∗ value(yellowness value)in IC3 and IC5 groups was significantly higher than that of IC0 and IC1 groups(P<0.05).(4)There was no significant difference in hardness,adhesion,cohesion,elasticity,gumminess and chewiness of back muscles between groups(P>0.05).(5)In terms of intestinal metabolism,lipids and lipid-like molecules were the most abundant among the top 20 small-molecule metabolites.Compared with the control group,6 metabolites were significantly upregulated and 10 metabolites were significantly downregulated in the experimental groups,with Trigoneoside ⅩⅢa and Radiprodil being the most upregulated metabolites.The results indicate that the supplementation of I.cicadae in the diet can promote the growth of juvenile large yellow croaker,improve body color,and increase the abundance of beneficial metabolites in the intestine.