Reference intervals for metabolic profile of adult sheep in the tropics: over 12 months

Abstract Metabolite levels can vary according to the farming region, age, physiological state and feeding of the animal, therefore, the objective was to estimate reference values for the energy, hepatic and mineral profiles of sheep (above 12 months) in the tropics. For this, data from healthy adult sheep, raised in different management systems in Brazilian institutions from 2006 to 2017 were used. To determine the energy profile, data were obtained for glucose, cholesterol, triglycerides, fructosamine, HDL (high density lipoprotein), LDL (low density lipoprotein) and VLDL (very low density lipoprotein); for the protein profile, total protein, uric acid, urea, albumin and creatinine data; for the mineral profile, values of calcium, phosphorus and magnesium; and for the enzymatic profile, data on AST (aspartate aminotransferase), GGT (gamma glutamyl transferase), alkaline phosphatase. The estimation and determination of reference values was performed in the RefVal 4.11 software, where outliers were removed, using the Dixon test, and the percentiles, as well as their confidence intervals, estimated by the non-parametric bootstrap method, when data did not show normal distribution. The defined confidence interval was 95%. Most metabolites presented intervals extrapolating both the lower and upper limits recommended in the international literature, especially cholesterol, fructosamine, urea and phosphorus. As for the enzymatic profile, the AST and alkaline phosphatase intervals assumed, as an upper limit, values below those recommended by the international literature. In conclusion, the intervals defined from the national data present differences in relation to the international ones, since only adult animals were considered, while those from international data do not make a distinction regarding the animal category.