It is investigated the calcium, phosphorous and magnesium homeostasis in cows in the dry period, cows in child-birth and calves in connection with the diarrhea in the newborn during the neonatal period, with the respiratory syndrome in the growing up, with the sterility in heifers, with the stillborn, with estrous and postestrous metrorrhagia. It was ascertained a close dependence in the value of Ca, P and Mg in the different physiologic groups of a given farm. It was ascertained that the newborn from mothers with lower serum values of Ca of 2.5 mmol/l, P of 1.8 mmol/l and Mg of 0.70 mmol/l suffer from diarrhea, endotoxic shock, tetany etc. during the neonatal period. Hypocalcemia is registered in the calves with a respiratory syndrome (2.20 mmol/l), sterile heifers (2.39 mmol/l). In all cases is ascertained hypophosphorosis and hypomagnesemia especially in the calves with a respiratory syndrome (P = 1.24 and Mg = 0.46 mmol/l), cows with a still born calves (P = 0.92 and Mg = 0.54 mmol/l) with metrorrhagia (P = 0.93 and Mg = 0.71 mmol/l). The diagnostic value of the product Ca X P X Mg is discussed. A reversible relationship between them is ascertain In comparison with the ideal in which Ca X P X Mg is 11.11 and the ratio--1.09, in the above mentioned diseases the product decreases and the ratio increases. The differences are graded which shows their mutual origin. It was established experimentally that the addition with a medical aim to the ration of the green pea-oats and green rye during spring and summer, such as oats in winter for the pregnant cows has a decisive effect on the living of the newborn. It was ascertained as well that in extra situations a component containing, calcium gluconate, magnesium sulphate, sodium salicylate, analgin, B1 vitamin, vitamin C, sodium phosphate, glucose and sodium chlorate (if necessary sulfathiazole) injected s.c. 5 times to the pregnant cows 15-5 days before childbirth has a positive effect on the new-born calves.