Effect of Haematococcus pluvialis on growth performance, antioxidant capacity and immune responses of Lates calcarifer

Haematococcus pluvialis is enriched in astaxanthin. To investigate its effects in the diet of Lates calcarifer, we fed L. calcarifer by six diets containing 0 (C), 0.2% (H1), 0.4% (H2), 0.6% (H3), 0.8% (H4) and 1.0% (H5) H. pluvialis for 56 d. The results show that the specific growth rate (SGR) and weight gain rate (WGR) in H2, H3, H4 and H5 groups were significantly higher than those of the control group (P<0.05). Compared with the control group, the whole-body lipid protein content decreased significantly in the treatment groups (P<0.05). The dietary H. pluvialis improved the total antioxidant capacity (T-AOC) significantly (P<0.05), while the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) activities and malondialdehyde (MDA) content were significantly lower than those of the control group (P<0.05). Compared with the control group, the concentrations of red blood cell (RBC), hemoglobin (Hb) and complement 4 (C4) increased (P<0.05) in H3, H4 and H5 groups, but the concentration of low-density lipoprotein cholesterol (LDL-C) decreased significantly (P<0.05). Compared with the control group, the concentrations of cholesterol (TCHO) and triglyceride (TG) decreased significantly (P<0.05), but the lysozyme (LYZ) activity and immunoglobulin (IgM) concentration increased significantly (P<0.05). The regression analysis on the WGR indicates that the recommended optimum dietary H. pluvialis level for the growth of L. calcarifer is 0.66%.