Effects of supplemental dietaryHaematococcus pluvialison growth performance, antioxidant capacity, immune responses and resistance toVibrio harveyichallenge of spotted sea bassLateolabrax maculatus

Abstract

The present study was conducted to investigate the effects of Haematococcus pluvialis on growth performance, antioxidant capacity, immune responses and resistance to Vibrio harveyi of spotted sea bass Lateolabrax maculatus. Fish were fed with six diets containing grade levels of containing H. pluvialis (0, 2, 4, 6, 8 and 1 g/kg, respectively) in triplicate for 8 weeks, followed by a V. harveyi infection test for 7 days. The astaxanthin concentrations of diets were 1.14 (control), 30.23 (T1), 58.42 (T2), 91.51 (T3), 118.61 (T4) and 150.31 mg/kg (T5). Results showed that dietary H. pluvialis increased final body weight (FBW), weight gain rate (WGR) and specific growth rate (SGR) and decreased the whole body lipid of fish (p < .05). Dietary H. pluvialis improved the hepatic total antioxidant capacity (T-AOC) and decreased the levels of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) activities, and malondialdehyde (MDA) contents of fish (p < .05). In fish fed the H. pluvialis supplemented diets, the levels of triglyceride, cholesterol and low-density lipoprotein cholesterol (LDL-C) contents decreased (p < .05). Moreover, dietary H. pluvialis improved the complement and immunoglobulin (Ig) contents, and lysozyme (LYZ) activities (p < .05). After challenge with V. harveyi, the survival rate in T2, T3, T4 and T5 was significantly higher than that of control, and the highest survival rate was in T3 (p < .05). These results indicated that dietary supplementation with the suitable level (0.4%-0.6%) of H. pluvialis could promote growth performance and hepatic antioxidant capacity, and enhance immune responses and resistance to V. harveyi challenge of L. maculates.

Effects of Nitrogen and Light Intensity on the Astaxanthin Accumulation in Motile Cells of Haematococcus pluvialis

“…H. pluvialis could accumulate high levels of astaxanthin (3-5% dry weight) (Lorenz and Cysewski, 2000;Ambati et al, 2014) and is regarded as the most potent natural source of astaxanthin (Bowen et al, 2002). Several studies indicated that dietary supplementation of H. pluvialis would improve the color, immune and antioxidant capacity of fish (Moretti et al, 2006;Sheikhzadeh et al, 2012;Li et al, 2018;Yu et al, 2021). However, H. pluvialis red cysts typically have thick and less digestible cell walls (Hagen et al, 2002;Shah et al, 2016), which reduce the bioavailability of astaxanthin (Sommer et al, 1991;Choubert et al, 2006).…”