Effects of emodin and vitamin E on the growth and crowding stress of Wuchang bream (Megalobrama amblycephala)

After crowding stress, the vit E group had improved serum TP 12 h post-stress, hepatic SOD activity 24 h post-stress, and hepatic HSP70 mRNA levels 12 and 24 h post-stress while the emodin group had enhanced serum SOD activity 12 and 24 h post-stress and hepatic HSP70 mRNA levels 12 and 24 h post-stress, as compared with the control. However, the serum cortisol content of the three treatment groups 12 and 24 h post-stress, ALT activity in the vit E group and emodin group 24 h post-stress, and serum alkaline phosphatase and liver catalase activity in the combination group 24 h post-stress were lower than those in the control group. The cumulative mortality was lower in the emodin, vit E, and combination group after Aeromonas hydrophila infection compared with the control group. Therefore, dietary supplementation with 60 mg/kg emodin or 500 mg/kg vitamin E can improve HSP70 mRNA levels and antioxidant capabilities, resistance to crowding stress, and growth in M. amblycephala. However, the combination of emodin and vit E does not have a synergistic effect in M. amblycephala.