Effect of Spirulina platensis on growth, hematological, biochemical, and immunological parameters of Nile tilapia (Oreochromis niloticus)

This study was conducted to evaluate the effects of Spirulina platensis in Nile tilapia diets on growth performance, blood hematological and biochemical parameters, immunological status, and intestinal histomorphometry. A total of 228 fish were randomly allocated into four groups with triplicates (19 fish per replicate). The first group was fed the control diet, which contained no Spirulina supplementation. The other three groups were fed diets containing graded levels of powdered Spirulina: 2.5%, 5.0%, and 10.0% in the second, third, and fourth group, respectively. S. platensis was added to the diets partially substituting the fish meal content. The experiment lasted for 8 weeks. The results showed that dietary Spirulina supplementation improved (P < 0.05) the body weight and length, weight gain, specific growth rate, condition factor, and feed conversion efficiency. Moreover, Spirulina increased significantly (P < 0.05) the hemoglobin, PCV, RBCs, and WBCs count. Also, it increased the lymphocytes, eosinophils, IgM level, lysozyme activity, and phagocytic activity in the blood. Additionally, the Spirulina raised (P < 0.05) the serum albumin level but reduced (P < 0.05) the creatinine and urea levels. The addition of Spirulina increased (P < 0.05) the height and width of intestinal villi and the lymphocytes and goblet cells count in the intestine. The obtained results were increased by increasing the inclusion level of Spirulina, especially for body weight and length, weight gain, FCR, phagocytic activity, and intestinal parameters. In conclusion, supplementing S. platensis can improve the growth performance of fish. Moreover, it can stimulate the immunity of fish through increasing the level of immunological blood indicators (IgM, lysozyme, phagocytic activity, lymphocytes, and eosinophils) as well as the local intestinal immunity (lymphocytes and goblet cells). So, it can be recommended to use S. platensis in fish diets not only to improve the growth performance but also to enhance the immune status.