[The effect of the time of day on the renal excretion of several minerals in cattle].
Urine of 17 cows was totally collected with a permanent bladder catheter for 3-5 days. The quantities of excreted calcium, magnesium, sodium, potassium, and inorganic phosphorus were evaluated. In a second experiment 448 urine samples, spontaneously excreted at different times of day, were analysed concerning the concentrations of the specified minerals and of creatinine. In order to avoid a possible misinterpretation the relations of the concentrations of the minerals and of creatinine concentration in each sample were computed. In both experiments it is shown that excretion of potassium and magnesium doesn't considerably differ at different times of day. Calcium, sodium and inorganic phosphorus, however, show maxima of excretion in the middle of each day and minima at midnight. Possible reasons for this phenomena and the meaning for use in diagnosis are discussed.