Browsing by Subject "indices of heart rate variability"

The heart rate of an individual varies all the time. This phenomenon is called heart rate variability. Both respiration and physical activity induce variations in heart rate. Heart rate variability can be assessed by studying electrical changes in the heart cycle. Electrical changes can be monitored by measuring ECG (electrocardiography). The main target of this study was to find out cow’s normal heart rate variability while they were awake, ruminating or sleeping. For this study, the heart rate of nine cows was recorded as well as their behavior during that time. Cows were monitored while they were sleeping, ruminating, standing or lying down. Four of the cows were from Finland and five of them from Sweden. From those nine cows, 543 one minute samples were obtained. This was the first time that cow’s heart rate was studied during their sleep cycle. The cows were not stressed in any way and their autonomic nervous system was not affected by drugs. One minute samples were analyzed. Samples were gathered by using a Matlab-based computer program, CowSS. All samples were checked visually, and all errors, for instance missing S-peaks or the errors caused by timing, were corrected. Statistical analysis was made by using a linear mixed effects model. According to the analysis, the best way to represent a cow’s heart rate variability is to use RMSSD-value. RMSSD-value describes the variations of adjacent intervals in different recordings. The result of this study show that during sleep the heart rate and the heart variability of cows are different from humans´. Cows´ sleep periods (NREM- and REM-sleep) are shorter and during REM-sleep the parasympathetic toning is stronger in cows. Cow is herbivore and prey for many predators, which may well explain the dominance of the parasympathetic system. Parasympathetic toning works faster than sympathetic toning, and this may give the cow a better chance to escape.