A Comparison of Biochemical Composition and Bioactivity of Abalone (Haliotis spp) Subjected to Different Diets and Treatments

Abstract

The fast growth of the aquaculture sector has led to an unsustainable harvest of wild fish species used in the production of aquaculture feed. Integrated Multi-trophic Aquaculture (IMTA) promises ecological and socio-economic advantages that include the provision of sustainable aquaculture feed. However, the promotion of IMTA requires that the stakeholders have sufficient quantitative information associated with its implementation. This present study compared the biochemical composition and bioactivity of the abalone, Halitosis tuberculata coccinea that was fed IMTA-produced macroalgae with the same species samples fed with an artificial diet, and a hybrid diet of the macroalgae and the artificial diet. The biochemical analyses of H. tuberculata coccinea extended to the impact of two aquaculture systems, the flow-through system (FTS) and the recirculation system (RS), used within an IMTA framework. In an additional part of this project, the effects of heat processing on abalone using cultivated animals of raw and heat-processed Haliotis midae were evaluated. The biochemical analyses included quantification of fat and protein content, determination of lipid class, fatty acid, and amino acid composition. To compare the bioactivity of samples, antioxidative capacity and HMG-CoA reductase inhibitory activity were tested. Significant differences in biochemical composition were found among the compared groups. The abalone that was fed macroalgae from IMTA had higher protein and fat content than the abalone fed with the artificial diet. However, a higher content of the beneficial omega-3 fatty acids was found in the abalone fed with the artificial diet, whereas its amount of essential amino acids was less than that of the abalone fed IMTA-macroalgae. Biochemical differences between samples from FTS and RS were minor. For the H. midae samples, it was shown that heat processing reduced the content of fatty acids and amino acids; some antioxidative capacities were enhanced whereas the fat content was not affected. Findings from this study indicate that macroalgae produced in IMTA meet abalone’s nutritional needs and that macroalgae can be used as a supplement or a replacement for the fishmeal-based diets used in abalone aquaculture.