Effects of dietary macroalgae meal and lipid source on growth performance and body wall fatty acid composition of sea cucumber Apostichopus japonicus

A 70‐day experiment was conducted to examine the effects of different macroalgal meals and lipid sources on growth, body wall composition and fatty acid ( FA ) profile of sea cucumber Apostichopus japonicus . Two macroalgal meals including Sargassum muticum ( SM ) and Gracilaria lemaneiformis ( GL ) and two lipid sources including fish oil ( FO ) and vegetable oil ( VO ) were formulated into four diets, i.e., S. muticum and fish oil ( SF ), S. muticum and vegetable oil ( SV ), G. lemaneiformis and fish oil ( GF ) and G. lemaneiformis and vegetable oil ( GV ). The results showed that the specific growth rates ( SGR ) of A. japonicus fed diets containing SM were significantly higher than those fed diets containing GL . No significant differences in SGR between the FO ‐based and VO ‐based groups were observed. Similar results were observed in the body wall lipid content. Most body wall FA s changed to resemble the dietary FA proportions because of the dietary effect. Concentrations of 20:4 n ‐6 of the SF and GF groups were significantly lower than the SV and GV groups, while levels of 20:5 n ‐3 and 22:6 n ‐3 were significantly higher than the SV and GV groups. The n ‐3/ n ‐6 polyunsaturated fatty acids ( PUFA ) ratios of the SF and GF groups were significantly higher than the SV and GV groups. Moreover, the SF group had significantly higher 20:5 n ‐3 and 22:6 n ‐3 contents and n ‐3/ n ‐6 PUFA s ratio than the GF group. These findings reveal that the SF diet can show beneficial effects on both growth performance and body wall n ‐3 PUFA s content of A. japonicus .