Metabolic profile assesment in brown trout (Salmo trutta fario) by mid infrared spectroscopy

The metabolic profile (MP) could be considered a set of information describing nutritional or health status. The haematic parameters depend on feeding, rearing conditions and water quality. Changes of some specific target can be used in preventive health examination. The study of Mid-Infrared spectrum (MIR - λ 400-4000 cm-1) provides a wide range of information regarding organic compounds. This work showed the potential analytical application of MIR on plasma of brown trout (Salmo trutta fario). Samples were collected from Broodstock (B, n= 24) and Fattening (F, n= 29) anaesthetized fish. The MP was assessed by using a BM Hitachi 911 analyzer. The parameters analyzed were: total protein (TP), albumin (ALB), globulin (GLOB), glucose (GLUC), cholesterol (CHOL), triglycerides (TRIG), non-esterified fatty acids (NEFA), aspartate aminotransferase (AST), amylase (AMY). The spectra were collected using Thermo Avatar FT-MIR. 150 µl of plasma was distributed in a thin layer on a ZnSe surface and then dried. Partial least square regression with mathematical pre-treatments was adopted. PRESS (Prediction Residual Error Sum of Square) was used to define the factor numbers. Satisfactory performances for qualitative assessment (r2= coefficient of determination in cross-validation) were obtained for protein (TP, r2= 0.81; ALB, r2= 0.76; GLOB, r2= 0.66), CHOL (r2= 0.78) and TRIG (r2= 0.71). The Broodstock showed some parameters at paraphysiological levels due to the reproductive phase. The principal component analysis (PCA) allowed the differentiation between F and B fish (91% correctly classified). The MIR allowed a quick monitoring of stock reared as regards to main markers of MP.