Effects of dietary administration of Echinacea purpurea on growth indices and haematological indices in common carp (Cyprinus carpio).

This study was conducted to determine the effects of Echinacea purpurea (EP) root on the growth performance and some haematological parameters of juvenile common carp (Cyprinus carpio). Echinacea meal was incorporated into the diets as follows: no Echinacea meal (E-0), 5 g Echinacea meal kg-1 diet (E-5), 10 g Echinacea meal kg-1 diet (E-10) and 20 g Echinacea meal kg-1 diet (E-20). Triplicate groups of fish averaging 9.6 ± 0.5 g were hand-fed twice daily for 60 days. At the end of the feeding trial, weight gain (WG), feed conversion ratio (FCR), and specific growth rate (SGR) were significantly higher in fish fed the Echinacea-supplemented diets than in those fed the control diet. Red blood cell count (RBC) and white blood cell count (WBC) were significantly higher in the E-10 and E-20 groups than in the E-0 group. Fish fed the E-10 diet had the highest haematocrit (Hct), and haemoglobin (Hb) among all treatments. The nitroblue tetrazolium (NBT) assay showed a significant increase in the E-10 and E-20 groups compared to the E-0 and E-5 groups. After a 14-day challenge with Aeromonas hydrophila, Kaplan-Meier analysis revealed significant differences in survival between treatments. Survival of carp following the challenge was significantly higher in fish fed the E-10 and E-20 diets than in the E-0 group, whereas the E-5 group showed no significant difference compared to the E-0 group. In conclusion, our findings revealed that supplementing diets with EP root (10 g EP kg-1 and 20 g EP kg-1 diet) can enhance growth performance, haematological parameters, and resistance to A. hydrophila in juvenile common carp.