| In the present study,the effect of dietary Reynoutria japonica extract on the growth performance,plasma biochemical parameters,antioxidant capacity,and survivor rate against Aeromonas hydrophila in crucian carp(Carassius arassius)was investigated for 60 days.Seven experimental diets were prepared,containing the extract of Revnoutral japonica(ERJ)(0,25,50,100,200,400,800 mg/kg).Results have shown that fish fed ERJ3 had the highest final body weight(FBW),body weight gain(BWG),and specific growth rate(SGR).However,all the groups fed diets with R.japonica extract supplement were not significantly(P > 0.05)different from the control group as well as feed conversion ratio(FCR).However,the majority of the plasma biochemical indices were significantly influenced.The influence on plasma biochemical indices was not consistent among the treatment groups,the groups showed a fluctuating trend.Exposure of C.auratus to ERJ6 diet significantly(P < 0.05)reduced plasma glucose(Glu)compared to the control group,while the rest of the treatments were not significantly different from the control.Total protein(TP)and albumin(ALB)levels were significantly(P < 0.05)elevated in R.japonica supplemented diets than the control,except for fish fed ERJ2 and ERJ6 diets.In contrast to the fish fed no ERJ diet,AST content of fish fed ERJ3 and ERJ4 were higher as well as ALT content of fish fed ERJ3-6(P < 0.05).ALP content of fish fed ERJ2-4 was significantly decreased compared with the control(P < 0.05).Cholesterol(TC)and triglyceride(TG)levels were significantly(P < 0.05)improved in fish fed ERJ5 and ERJ6 than the control.High-density lipoprotein(HDL)was no significant different compared to the control(P(29)0.05).However,low-density lipoprotein(LDL)content was significantly improved apart from the fish fed ERJ4(P < 0.05).Finally,there was no difference in the activity of plasma LDH among all groups(P > 0.05).After 60 days of feeding,the antioxidant related indexes in liver and enzyme activity in anterior intestine were measured.The results showed that MDA activity was significantly(P< 0.05)reduced in fish fed ERJ5 and ERJ6 diets compared to the control group.SOD activity was raised significantly(P < 0.05)in all the diets compared to the control,except for ERJ4 which was similar to the control.Meanwhile,compared to the fish fed ERJ1 and ERJ5-6,CAT activity was increased in the fish fed ERJ0 and ERT2-3,while there was no significant difference among them.Finally,GSH-PX activity was significantly raised in fish-fed ERJ2 and ERJ4 than the other groups.LZM activity in the anterior intestine was significantly(P <0.05)elevated when the fish were fed with ERJ5 diet,while LPS was reduced significantly(P < 0.05)than the control group.Besides,there were no significant changes in hepatocytes between all groups,indicating that R.japonica did not cause damage to the liver cells,even at very high concentrations,such as 400 mg/kg.Thus,the basal diet supplemented with R.japonica could improve the liver antioxidant and intestinal antibacterial capacities of crucian carp.After 60 days of feeding,the serum immunological indexes and the immune related gene expression were measured.Results showed that Ig M content in the plasma was observed to be significantly reduced than that of fish fed no ERJ supplemented diet(P < 0.05).C3 content of fish fed ERJ1,ERJ4 and ERJ6 were significantly lower compared to that of fish fed control,while there was no difference in C3 content among all experimental groups(P > 0.05).Besides,Fish fed ERJ 100mg/kg diet illustrated the lowest C4 content(P > 0.05).The relative m RNA expressions of TNF-α,NF-κB,and IL-11 in the liver were measured.The results revealed that expression levels of three genes were all reduced in fish fed ERJ diets in varying degrees(P > 0.05).After the challenge with A.hydrophila for 5 days,all ERJ supplemented treatments displayed an increased survival rate.Thus,the basal diet supplemented with ERJ could improve non-specific immunity and enhance disease. |
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