[Study of ECG in lactating cows. 2: ECG compared to behavior of various parameters of mineral and carbohydrate-fat metabolism].

Four electrocardiographic recordings were taken from 52 cows in a high-performance dairy cattle stock, between the time of calving and the end of the third month of lactation. The voltage of all peaks dropped in the second to fourth weeks after parturition and went up significantly during the second month of lactation. The changes were attributed to tonogenic voltage rise of the heart. Additional tests were applied to 16 cows which had been given increased protein amounts in their feed rations over a prolonged period of time. Their PQ-interval was prolonged in comparison to eight controls.