Dietary effect of Spirulina platensis on growth performance, digestive enzymes, haematological indices and antioxidant capacity of Chinese sea bass (Lateolabrax maculatus)

Chinese sea bass (Lateolabrax maculatus) with initial body mass of (25.49±0.20) g were fed for eight weeks with six diets containing 0 (control), 1% (T1), 2% (T2), 3% (T3), 4% (T4) and 5% (T5) Spirulina platensis, so as to investigate the effect of S. platensis on the growth performance, digestive enzymes, haematological indices and antioxidant capacity of L. maculatus. The results show that the dietary supplementation with S. platensis improved the weight gain rate (WGR) and specific growth rate (SGR) of L. maculates (P<0.05) significantly. The feed conversion ratio (FCR) decreased significantly (P<0.05). The protease activities in S. platensis supplemented groups were significantly higher than that of the control (P<0.05), while no significant change was observed in lipase and amylase activities among different groups. Compared with the control, the levels of red blood cell (RBC) increased in T4 and T5 groups significantly (P<0.05), and levels of white blood cell (WBC) and hemoglobin (Hb) in T3, T4 and T5 groups were significantly higher than those of the control (P<0.05). The levels of triglyceride, cholesterol, low-density lipoprotein cholesterol (LDL-C) in T4 and T5 groups decreased significantly than those of the control (P<0.05). The total antioxidant capacity (T-AOC), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities in T3, T4 and T5 groups were significantly higher than those of the control (P<0.05). The malondialdehyde (MDA) contents in T3, T4 and T5 groups were significantly lower than those of the control (P<0.05). It is suggested that the suitable S. platensis supplementation level in diet of L. maculates is 4%−5%.