Effects of vitamin C deficiency or excess on growth performance, anti-oxidative response and fatty acid composition of juvenile abalone Haliotis discus hannai Ino

Abstract

A 240-day feeding trial was conducted to investigate the effects of dietary vitamin C on growth performance, anti-oxidative response, and fatty acid composition of juvenile abalone Haliotis discus hannai Ino (initial body weight: 0.93±0.00 g). Three semi-purified experimental diets were formulated containing 0.00, 94.52, and 9 649.58 mg/kg of vitamin C supplied as L-ascorbyl-2-monophosphate. The results show that there was no significant difference in weight gain ratio, daily increment in shell length, and survival rate among the three treatments. Adding dietary vitamin C (9 649.58 mg/kg) significantly increased the activities of superoxide dismutase (SOD), glutathine peroxidase (GPX), glitathione-S-transferase (GST), glutathione reductase (GR), alkaline phosphatase (AKP), and lysozyme in viscera (P<0.05). In muscle, activities of phenoloxidase, catalase, SOD, GST, GR, and AKP were increased in the treatment with 9 649.58 mg/kg of dietary vitamin C (P<0.05). The highest concentrations of ascorbic acid in viscera and muscle were found in the group with 9 649.58 mg/kg of dietary vitamin C (P<0.05). The contents of crude protein and crude lipid in the soft body were significantly increased in the 9 649.58 mg/kg group (P<0.05). Dietary vitamin C supplementation significantly decreased the contents of saturated fatty acids (14:0, 16:0, and 18:0), and increased the composition of 18:2n-6 and 22:6n-3 in the soft body of abalone (P<0.05). Therefore, although there were no significant effects on the growth performance, dietary vitamin C supplementation improved the anti-oxidation and immune responses, increased specific unsaturated fatty acid (i.e., 16:1, 18:1n-7, 18:1n-9, 18:2n-6 and 22:6n-3), and decreased specific saturated fatty acid (i.e., 14:0, 16:0 and 18:0) contents in the soft body of abalone.