Comparative studies on the nutrition of two species of abalone, Haliotis tuberculata L. and Haliotis discus hannai Ino. III. response of abalone to various levels of dietary lipid

This study was carried out to evaluate the effects of graded dietary lipid levels on the survival, growth and body composition of Haliotis tuberculata and H. discus hannai. Six purified diets were formulated to provide approximately 25% protein, and a series of graded lipid levels, from 0.63 to 11.58%, in the form of a mixture of corn oil and menhaden fish oil (1:1). The red alga, Palmaria palmata, was used as a control diet. Abalone juveniles of similar size (H. tuberculata, 588 mg; H. discus hannai, 389 mg) were distributed in a recirculating system using a completely randomized design with 7 treatments and 3 replicates per treatment (20 juveniles/replicate), and fed the appropriate diet every 3rd day for a 100-day period. P. palmata produced similar or better growth performance for both abalone species than the artificial diets. Among the artificial diets, significantly higher weight gains were observed for H. discus hannai at dietary lipid levels ranging from 3.11 to 7.09%, and for H. tuberculata at 3.11%. However, growth in terms of protein gain was best when both species of abalone were fed 3.11 and 5.15% dietary lipid. Soft-body lipid content positively correlated with dietary lipid levels. Inversely, soft-body protein concentrations decreased with the increase of dietary lipid. Overall, H. discus hannai deposited a slightly higher level of lipid, but a lower level of protein than H. tuberculata. There were no significant differences in survival of abalone fed the experimental diets.