Effects of mequindox on non-specific immunity, growth performance and stress resistance of juvenile sea cucumber Apostichopus japonicus

Abstract:

The present study aimed to evaluate the effects of mequindox on non-specific immunity, survival rate, growth performance and stress resistance in juvenile sea cucumber (Apostichopus japonicus) breeding. The sea cucumbers with initial body weight of 0.6g were exposed to different mequindox solutions of 0 (control group), 0.5, 1.0, 2.0, 4.0 and 6.0 mg/L for 69 days. The resistance after long-distance transportation was investigated two weeks after the drug withdrawal. The results showed that the AKP, ACP and SOD enzyme activities of juvenile sea cucumber increased significantly after the use of mequindox, and reached peak in the 2.0 mg/L, 4.0 mg/L mequindox solutions and then decreased as the mequindox continued to increase. However, after 40 days, the enzyme activities in the experimental groups generally decreased to the values in the control group. Appropriate amounts of mequindox can increase the growth rate and survival rate of the sea cucumber. The final body weight (FBW), weight gain rate (WGR) and specific growth rate (SGR) in the experimental groups were significantly higher than those in the control group (P<0.05). The FBW, WGR and SGR were the biggest in the 4.0 mg/L mequindox solution with the highest survival rate (90.6%), significantly higher than the other groups (P<0.05). Besides, high concentration of mequindox (6.0 mg/L) decreased the stress resistance of juvenile sea cucumber. Our study suggested that the proper amount of mequindox for juvenile sea cucumber in the period of growth seeding was approximately 2.0 mg/L-4.0 mg/L.