Effects of food processing method on digestibility and energy budget of Apostichopus japonicus

The type of diet used in aquaculture systems affects the feed digestibility and energy budget of the organisms under culture. In this study, the sea cucumber Apostichopus japonicus (Selenka) was fed diets produced using four different processing methods (extruded pellet diet, cold-bonded pellet diet, flake diet, and mash diet), and growth performance, digestibility, digestive enzyme activity, and energy budget were quantified for 60 d to identify the optimal feed type for use in culturing this species. The specific growth rate ranged from 0.51 to 0.96; the highest rate occurred in specimens fed the extruded pellet diet and the lowest rate was found in those fed the cold-bonded pellet diet. Sea cucumbers fed the extruded pellet diet had the highest energy deposition as growth (11.45%), whereas specimens fed the mash diet had the lowest (5.79%). The apparent digestibility coefficients for dry matter (ADMD) and gross energy (AGED) of sea cucumbers fed the extruded pellet diet was higher than that of A. japonicus fed the other diets. When animals were fed the extruded diet, the amylase activity in the gut was significantly higher than in animals fed the mash diet (42.61 vs. 28.40). However, the protease activity was significantly higher in animals fed the mash diet than the extruded diet (7.75 vs. 5.55). Overall, the results of this study indicate that the extruded pellet diet is the optimum feed type for use in the culture of A. japonicus.

► It is the first time to study the feed process method for sea cucumber.
► The first study to use growth, digestibility, energy budget to evaluate feed quality.
► The results will give good suggestion for formulated feed of A. japonicas.
► The research showed that extruded pellet feed is the best choice for sea cucumber.