[Mineral metabolism in calves during periods of milk feeding and weaning based on selected parameters in the blood].

Concentrations of calcium, inorganic phosphorus, magnesium, sodium and potassium (Tab. I) were followed in the blood serum of calves in the period of milk diet and weaning (at the age of nine weeks), and the results were evaluated with respect to their deviations from the reference values. The average concentrations of calcium and inorganic phosphorus did not show any significant variations and they were within the range of reference values. Magnesium concentrations in the blood serum of calves on all-vegetable diet (11 weeks of age) were significantly higher (p < 0.01) in comparison with the starting value (at the age of two weeks) while they approached the lower boundary of reference range as late as at the age of nine weeks (Fig. 1). The highest percentage of hypocalcaemia (33.3%) and hypophosphataemia (47.3%) in individual animals was determined at weaning. The highest level of hypomagnesaemia was observed at the age of two and five weeks (57.1% of the calves). The subnormal values of the mentioned parameters were markedly adjusted in the calves on all-vegetable diet (Fig. 2). The concentrations of serum sodium and potassium (Fig. 3) were decreasing in the calves on milk diet, but after weaning they were stabilized at the values which were recorded at the age of five weeks (Na 146.3 mmol/l and K 5.19 mmol/l). With the exception of weaning, the average sodium concentrations in the blood serum of calves were slightly above the upper boundary of the reference range, their significant drop was observed only at weaning (p < 0.05). The concentrations of serum potassium were within the range of reference values except the values at the age of two weeks and the potassium concentrations in the serum were significantly lower at the age of 5, 9 and 11 weeks in comparison with the starting value (p < 0.01). The highest percentage of hypernatraemia (81%) and hyperkalaemia (85.7%) was determined in individual animals at the age of two weeks (Fig. 4).