Electrolytes, heart rate, and heart rate variability during the peripartum period in Holstein cows

Abstract

There are no studies that correlate electrolytes with heart rate (HR) and heart rate variability (HRV) during the peripartum period in cows. In theory, electrolyte concentrations in serum can directly affect HRV by influencing the excitability of the heart muscle. Twenty-three cows of the Holstein breed were studied. HRV indexes were analyzed in six moments by electrocardiography. The indices were evaluated in the time domain and frequency, standard deviation of successive intervals (SDNN), root mean square of the average difference of successive intervals (RMSSD), low frequency (LF), and high frequency (HF), as well as the LF/HF ratio. Ca2+, Mg2+, and Pi concentrations were measured by means of spectrophotometry, as well as concentrations of Na+ and K+ by means of photometry. HR increased on the day before delivery and then decreased after delivery. The parasympathetic indices of RMSSD and HF increased. The sympathovagal balance between LF/HF decreased significantly. Concentrations of the electrolytes Ca2+ and Pi decreased after delivery, while Na+ concentration increased. The day before delivery, the LF index increased, while HF decreased, indicating HR modulation and ventilation via the vagus nerve. One day before delivery, K+ showed a strong association with the HF index. The day after delivery, the correlation between K+ and HR, HF, and LF showed a strong association