By the method of ECG telemetry was investigated the cardiac, activity in 245 cows, from which 125--in the lactation period, 48--pregnant and 112--new-calved. It was established that the cardiac frequency in pregnant cows is 83.3 min-1, in new-calved--83.7 min-1 and in milch-cows--86.3 min-1. The elements of ECG are similar in value for the separated groups of cows, and are in the limits for the peak P by amplitude--from 0.22 to 0.24 mV and duration--from 0.080 to 0.083 s, for the peak R the amplitude is from 1.17 to 1.20 mV and the duration--from 0.063 to 0.065 s. The values of interval and segment P--Q, of segment S-T, interval Q--T and segment T--P are shown. Proved are changes in the shape and duration of the T wave, which occurs as diphasic in the pregnant and new-calved cows--up to 45% and in the milch-cows--9.6%.
