Relationship between Non-Specific Immune Response and Body Size in Cultured Rainbow Trout

The aim of this study was to evaluate some blood parameters involved in non-specific immunity in order to assess the possible correlation with biometric indices (weight and length) in cultured rainbow trout Oncorhynchus mykiss (Walbaum, 1792). For this purpose sixty Italian cultured trout (350.00-950.00 g weight range, 28.00-40.00 cm length range) reared in a Sicilian farm were utilized in this research. In the farm, physico-chemical characteristics of water were measured. From each fish, blood samples were collected to evaluate White Blood Cells Count (WBC), Thrombocyte Count (TC), Ceruloplasmin (Cp), Total Protein (TP), serum albumin and serum protein fractions. Linear regression analysis was used to evaluate the relationship between the biometric indices and non-specific immune parameters. Results showed a statistically significant correlation between weight and length with ceruloplasmin. Our study suggests that nonspecific immune response in fish changes in relation to body size; this result is useful in order to obtain a wider knowledge of the non-specific immune parameters that may allow diversified vaccination plans in relation to the different size.