Effects of graded levels of dietarymyo-inositol on non-specific immune and specific immune parameters in juvenile Jian carp (Cyprinus carpiovar. Jian)

The aim of this study was to evaluate the effects of myo-inositol (MI) on non-specific immune and specific immune defence in fish. A total of 1050 Jian carp (Cyprinus carpio var. Jian) (22.28±0.07 g) were randomly distributed into seven groups, of three replicates each, of feeding diets containing graded levels of MI (163.5, 232.7, 384.2, 535.8, 687.3, 838.8 and 990.3 mg MI kg−1 diet). After a 60-day growth trial, an infectious trial was conducted by injection of Aeromonas hydrophila for 17 days. Results showed that the red blood cell (RBC) and the white blood cell count were significantly increased with increasing MI levels up to 535.8 mg kg−1 diet (P<0.05). The spleen index showed a tendency similar to RBC, whereas the head kidney index showed the inverse pattern (P<0.05). The phagocytic activity of leucocytes, haemagglutination titre, lysozyme activity, anti-A. hydrophila antibody titre and immunoglobulin M, after being injected with A. hydrophila, were all improved with an increase in the MI levels up to 232.7–687.3 mg kg−1 diet respectively (P<0.05). Myo-inositol did not influence serum acid phosphatase activity and total iron-binding capacity (P>0.05). These results suggested that MI could enhance non-specific immune and specific immune responses in fish.