Reference intervals for blood markers of mineral balance for groups of dairy cows in the South of Chile

Abstract

The aim of this study was to propose reference intervals (RI) for blood markers of mineral balance in prepartum and lactating groups of dairy cows in the South of Chile. The blood concentrations values of calcium, inorganic phosphate, magnesium, sodium, potassium, copper and zinc and ratio calcium/inorganic phosphate were analysed. The values were obtained from 1,414 metabolic profiles performed between 2003 and 2011 to groups of cows from dairy herds. Each metabolic profile consisted of a group of 5 or more cows, and according to their physiological condition they were classified in 2 categories: prepartum (n = 380) or lactating (n = 1,034). The means of the analytes were calculated for each group and category. The distribution of the data was analyzed and non-parametric values were log-transformed. For each analyte outliers were identified and removed. RI were estimated with a non-parametric test, based on the 2.5^th and 97.5^th percentiles when the sample size was ≥ 120, and with a robust method when the sample size was 40 ≤ n ≤ 120. The RI for most of the blood markers were similar to those reported previously by the laboratory, except for inorganic phosphate established for both categories and of copper for the prepartum category. The results of this study will improve the interpretation of metabolic profiles and its accuracy to assess the metabolic and nutritional status of prepartum and lactating groups of cows of dairy herds in the South of Chile.