THE LEVEL OF MINERAL METABOLISM IN CALVES IN RELATION TO AGE AND SEASON

Concentrations of calcium, inorganic phosphorus, magnesium, sodium, po tassium, vitamin A, and alkaline phosphatase activity were studied wit hin a year in the blood serum of calves on milk diet (2-4 weeks), duri ng transition to vegetable diet (6-8 weeks) and in calves on vegetable diet (10-12 weeks), kept on three farms under farming conditions. A t otal of 126 clinically healthy calves were examined. Serum concentrati ons of mineral elements in the calves under observation indicating ave rage values for calcium (2.39 +/- 0.2 mmol/l), inorganic phosphorus (2 .76 +/- 0.35 mmol/l), magnesium (0.74 +/- 0.2 mmol/l), sodium (135.9 /- 6.4 mmol/l) as well as for vitamin A (0.89 +/- 0.29 mmol/l) ranged within the reference values. Potassium concentrations (5.7 +/- 0.4 mmo l/l) and alkaline phosphatase activity (2.63 +/- 1.6 mu kat) exceeded on average the upper boundary of reference range. Evaluation of age dy namics (Tab. I) confirmed the lowest serum concentrations of magnesium , inorganic phosphorus and vitamin A in the youngest calves, with a gr adual increase in concentrations with age. Clear age dynamics was demo nstrated for alkaline phosphatase activity with the highest level in y oung calves. No trend of age dynamics was confirmed for calcium, sodiu m and potassium values. Individual evaluation of mineral element conce ntrations reveals the presence of hypomagnesemia, hypophosphatemia and hypercalcemia. In the case of seasonal dynamics (Tab. II), seasonal f luctuations of magnesium concentrations and alkaline phosphatase activ ity were confirmed for average values as well as for individual values , with the critical situation in summer when 80% presence of hypomagne semia was recorded in the calves under observation A trend of seasonal fluctuations with the lowest concentrations in the spring season was observed for serum values of inorganic phosphorus and vitamin A. The r elationship between a decrease in serum magnesium concentrations and a parallel increase in alkaline phosphatase activity in the blood serum of calves comes forth clearly within the analyses of mineral metaboli sm. Individual evaluation confirmed this relationship in 45% of calves on milk diet and 31% of calves on vegetable diet. Seasonal dynamics d emonstrated that 78% of calves in the summer season and 53% calves in the spring season showed an increase in alkaline phosphatase activity parallelly with a decrease in serum magnesium concentrations.