Published in Scientific Works. C Series. Veterinary Medicine, Vol. LVIII ISSUE 4
Written by Alina Anton, Gheorghe Solcan
Measurement of heart rate variability (HRV) is a non-invasive technique that can be used to investigate the functioning of autonomic nervous system, especially the balance between sympathetic and vagal activity. HRV is measured by determining the constantly changing temporal distance between succeeding heartbeats (R-R intervals). Five lacting cows, well trained to blood sampling were challenged with an intramuscular single dose (0.5 μg/kg) of ACTH (Synacthen Depot). HRV was measured for each cow for 5 min, at 0 h (before treatment) and every 30 min for 2 h. HRV parameters were analysed in the time domain, frequency domain and nonlinear components. Blood samples (10 mL) were collected from the coccygeal vein of all cows at 0, 30, 60, 90 and 120 min, after the measurement of HRV, for serum cortisol. The heart rate of cows increased significantly (P<0.05) under the influence of Synacthen administration. All computed time domain parameters declined significantly after ACTH administration. The decline of root mean square of successive interbeat interval differences (RMSSD) was more pronounced than that for standard deviation of all interbeat interval (SDNN), after ACTH administration. The power of low-frequency component divided by power of the high-frequency band (LF/HF) increased also within 30 min of administration of ACTH. All nonlinear parameters (%DET and %REC) exhibited a significant rise 30 min after ACTH administration. Serum cortisol concentration also increased (P < 0.05) within 30 min of administration in cows. The nonlinear parameters were most important to indicate the level of stress in cows. HRV is a valuable physiological indicator for stress in cows.
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frequency domain
