Immunomodulatory effects of chitin and chitosan enriched diets in Epinephelus bruneus against Vibrio alginolyticus infection

The present study determined the effects of chitin and chitosan enriched diets on hematology and immune response in kelp grouper, Epinephelus bruneus against Vibrio alginolyticus infection at weeks 1, 2, and 4. Red blood cells (RBC) significantly increased in grouper fed with chitin and chitosan supplementation diet against pathogen. White blood cells (WBC), haematocrit (Ht), and haemoglobin (Hb) significantly increased with any diet containing chitosan. However, mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), and mean corpuscular haemoglobin concentration (MCHC) significantly decreased. Lymphocytes and monocytes increased significantly when fed with chitosan enriched diets; however with 2% chitosan diet the neutrophils significantly increased. Total protein, albumin, and globulin significantly increased when fed with chitosan diets. Phagocytic activity and complement activity were not significantly enhanced with chitin enriched diets; but significantly increased with chitosan diets on weeks 1 and 2. The lysozyme activity was significantly enhanced from weeks 1 to 4 when fed with 2% chitin and chitosan diets. Mortality was lower in fish fed with chitosan than with chitin diets. The present results suggest that the dietary supplementation of chitin and chitosan stimulates the hematological and immunological parameters in E. bruneus against V. alginolyticus infection.

► RBC significantly increased in chitin and chitosan diets against pathogen.
► Phagocytic and complement activities significantly enhanced in chitosan diets.
► Lysozyme activity significantly enhanced in 2% chitin and chitosan diets.
► Mortality was low in chitosan diets than chitin diets against pathogen.