Effects of different feed ingredients on growth, fatty acid profiles, lipid peroxidation and aminotransferases activities of sea cucumber Apostichopus japonicus (Selenka)

A 70-day experiment was conducted to examine the effects of different feed ingredients on the growth, fatty acid (FA) profiles, lipid peroxidation and aminotransferases activities of sea cucumber Apostichopus japonicus. Sea cucumbers were fed with 6 types of diets with the ingredient of either single algal powder or mixture of algal powder and benthic matter mainly composed of microalgae, bacteria and clay particles, i.e., single brown alga Sargassum muticum (S), red alga Gracilaria lemaneiformis (G), green alga Ulva lactuca (U), mixture (1:1) of S. muticum and benthic matter (SB), mixture (1:1) of G. lemaneiformis and benthic matter (GB) and mixture (1:1) of U. lactuca and benthic matter (UB). After the feeding trial, the specific growth rate (SGR) of A. japonicus in the group GB was significantly higher compared to those in the group G while no significant differences were observed between the SB and S groups or between the UB and U groups. The biochemical compositions and FA profiles in the body tissues of A. japonicus were remarkably affected by the corresponding diets. The crude protein content of A. japonicus in the group UB was significantly higher relative to those in the group U while there were no significant differences between the SB and S groups or between the GB and G groups. A. japonicus fed diets containing benthic matter showed similar or elevated concentrations of n−3 polyunsaturated fatty acids (PUFAs) including eicosapentaenoic acid (20:5n−3, EPA) and docosahexaenoic acid (22:6n−3, DHA) as compared to those cultured with corresponding single algae diets. Moreover, dietary benthic matter improved the antioxidant capacity of A. japonicus to some degree during refrigerated storage at 4°C, and significantly increased the activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) except the AST activity of A. japonicus in the group UB. The results of the present study suggested that benthic matter might be used as a suitable substitute for the traditional macroalgae ingredients in A. japonicus feeds.The results of the present experiment provided the scientific foundation for optimizing the ingredients of the artificial feed for the farming of sea cucumber A. japonicus.