Dietary allicin improves behavior, physiology, growth, and disease resistance in the sea cucumber Apostichopus japonicus

It is important to establish a cost-effective method to improve behavior, physiology, growth, and resistance to Vibrio in sea cucumber aquaculture. The present study found that feeding behavior was significantly higher in sea cucumbers fed with dietary allicin (50.50 +/- 10.94 times) than that of those fed without allicin (24.38 +/- 1.86 times) (P = 0.049). Consistently, food intake significantly increased in sea cucumbers fed with allicin (P < 0.001). Further, dietary allicin significantly increased the height of intestinal folds in sea cucumbers. Glucose showed no significant difference between sea cucumbers fed with and without allicin. Glucokinase activity was significantly higher in sea cucumbers fed with allicin (103.96 +/- 5.59 U/L) than those without dietary allicin (82.36 +/- 6.18 U/L) (P = 0.041). This suggests that the increase of food intake induced by allicin in diet leads to an elevated glucose level in sea cucumbers, potentially maintaining a stable intracellular glucose level through the action of glucokinase to convert glucose into glycogen. In this study, the relative weight gain rate was significantly higher in sea cucumbers fed with allicin (0.270 +/- 0.053) than those fed without allicin (0.011 +/- 0.007) (P = 0.008). This suggests that dietary allicin stimulates the growth of sea cucumbers. Feeding behavior (P < 0.001) and crawling behavior (P = 0.001) of sea cucumbers fed with dietary allicin were significantly better than those of individuals fed without allicin after being soaked by bacterial liquid. Further, this study found that sea cucumbers fed with dietary allicin showed significantly higher levels of catalase (P < 0.001) and total superoxide dismutase (P = 0.001) than those fed without allicin, following the immersion in V. harveyi solution. The results suggest that allicin enhances the behavior and physiology of sea cucumbers exposed to V. harveyi. This study provides a cost-effective method to enhance production efficiency in sea cucumber aquaculture.