Abstract

The aim of this study was to describe and compare the frequency of mineral imbalances in groups of prepartum and lactating dairy cows in the south of Chile. The blood concentrations of calcium, inorganic phosphate, magnesium, sodium, potassium, copper and zinc, calcium:inorganic phosphate ratio and blood activity of the enzyme glutathione peroxidase, which indicates the selenium status, were analysed. The values were obtained from 3,216 metabolic profiles performed to groups of cows of Chilean dairy herds between 1986 and 2011. Each profile consisted of a group of 5 or more cows and according to their physiological condition and date in which the profiles were performed they were classified in categories (prepartum or lactating), periods (1986-2002 or 2003-2011) and seasons (summer, autumn, winter or spring). The means of the parameters in both categories were within the reference intervals used by the laboratory, with differences associated to period, category and season. The most common mineral imbalances were caused by deficiency of an element. From 1986 to 2002, hypomagnesemia and hyponatremia were the most frequent macrominerals disorders in prepartum and lactating categories, respectively, while between 2003-2011 the frequency of hyponatremia and hyperphosphatemia increased in both categories. The most common trace mineral imbalance in both categories was deficiency of selenium. The results indicate that dairy herds of the south of Chile have metabolic and nutritional imbalances of minerals, mostly deficiencies, with variations associated to the physiological condition of the group and season that show an increase in recent years.