Comparative studies on the nutrition of two species of abalone, Haliotis tuberculata L. and Haliotis discus hannai Ino. : VII. Effects of dietary vitamin C on survival, growth and tissue concentration of ascorbic acid

Abstract

The experiment was conducted to investigate the effects of dietary vitamin C on survival, growth and tissue ascorbic acid (AsA) concentration of abalone, Haliotis tuberculata and H. discus hannai. Eight purified diets were formulated to provide a series of graded levels of vitamin C (0–800 mg/100 g diet) from either supplemental crystalline AsA (1 level) or AsA coated with hydrogenated vegetable oil (7 levels). The red alga, Palmaria palmata, was used as a control diet. Abalone juveniles of similar size were distributed in a recirculating system using a completely randomized design with 9 treatments and 3 replicates per treatment. They were fed the appropriate diet every 3rd day for a 100-day period. Survival and growth of both abalone species were not significantly affected by the dietary treatments ( P>0.05); and no deficiency signs were observed. Tissue AsA concentration, however, increased with the increase in dietary AsA. Abalone fed the diet containing crystalline AsA (200 mg/100 g) had significantly lower levels of carcass AsA than those fed the ascorbate-free diet. P. palmata resulted in a similar (in H. tuberculata) or a higher (in H. discus hannai) tissue AsA level than the purified diet with the highest level of coated AsA. H. tuberculata had a significantly higher mean level of tissue AsA than H. discus hannai.