Hematite-biochemical and immune response of Caspian brown trout (Salmo troutta caspius, Kessler, 1877) juveniles fed different levels of spirulina (Spirulina platensis)

The effects of dietary Spirulina platensis on haemato-biochemical and immunity responses of Caspian brown trout (Salmo troutta caspius) juveniles was investigated. For this purpose, diets with five S. platensis inclusion levels (control, 2%FMR (13.2 g kg-1 spirulina in diet), 4%FMR (26.4 g kg-1 spirulina in diet), 6%FMR (39.6 g kg-1 spirulina in diet), and 8%FMR (52.8 g kg-1 spirulina in diet) were prepared. Six hundred juveniles with an average initial weight of 11±1.0 g were assigned to 15 experimental tanks. The experiment lasted for 10 weeks. At the end of the experiment, growth performance, haemato-biochemical parameters including white and red blood cell counts, neutrophils lymphocytes counts, hematocrit, hemoglobin, glucose, albumin, total protein, aspartate amino transferase (AST), alanine amino transferase (ALT), triglyceride, cholesterol, as well as immunity parameters including lysozyme, C3, C4, Immunoglobulin (IgM), ACH50 and respiratory burst activity were assessed. The results indicated that fish fed diets supplemented with 6%FMR and 8%FMR had a significantly higher weight gain (26.13 g and 25.88 g) and specific growth rate (1.74 %bw day-1 and 1.71 %bw day-1) compared with control. Furthermore, 6%FMR and 8%FMR treatments had statistically higher protein efficiency (0.76 and 0.78), lipid efficiency (1.89 and 1.94) and statistically lower feed conversion ratio (2.91 and 2.84) compared to the other treatments respectively (p<0.05). The physiological and immunological factors were improved when fish were fed a high level of S. platensis supplement. S. platensis inclusion also increased activity of Lysozyme C3, C4, IgM and ACH50 and respiratory burst activity and reduced AST and ALT formation. These results indicate that S. platensis supplement is promising for disease prevention in S. trutta caspius juveniles, at an optimum dietary level of 6% in diet.