Heart Rate and Heart Rate Variability Change with Sleep Stage in Dairy Cows

Abstract

Changes to the amount and patterns of sleep stages could be a useful tool to assess the effects of stress or changes to the environment in animal welfare research. However, the gold standard method, polysomnography PSG, is difficult to use with large animals such as dairy cows. Heart rate (HR) and heart rate variability (HRV) can be used to predict sleep stages in humans and could be useful as an easier method to identify sleep stages in cows. We compared the mean HR and HRV and lying posture of dairy cows at pasture and when housed, with sleep stages identified through PSG. HR and HRV were higher when cows were moving their heads or when lying flat on their side. Overall, mean HR decreased with depth of sleep. There was more variability in time between successive heart beats during REM sleep, and more variability in time between heart beats when cows were awake and in REM sleep. These shifts in HR measures between sleep stages followed similar patterns despite differences in mean HR between the groups. Our results show that HR and HRV measures could be a promising alternative method to PSG for assessing sleep in dairy cows.

Animal-based welfare indicators for dairy cows and their validity and practicality: a systematic review of the existing literature

“…Patterns were consistent across both groups, suggesting that HR and HRV changes correspond with sleep stages in cows. The findings also indicate associations between sleep stage, HR, and HRV, emphasizing their practical use in identifying sleep stages in dairy cows and enhancing accessibility for animal welfare research ( 96 ).…”

“…According to Hunter et al ( 96 ), analyzing dairy cow sleep patterns is crucial for understanding their well-being amid environmental changes or other stressors. The current gold standard, polysomnography (PSG), can be challenging to conduct.…”

The Effect of Drotaverine on Gastrointestinal Motility and Heart Rate Variability in Normal, Resting Horses

“…In cows, the authors found that HR decreased with sleep depth and REM was associated with increased HRV. Regarding non-REM sleep stages, cows presented more activity of the parasympathetic while sympathetic nervous systems was reduced [97]. In humans, during sleep, RMSSD and HF parameters are reduced, suggesting a decrease in vagal modulation of heart rate [98].…”

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“…These differences are explained by the cow's different perception of the environment and adaptation to the changes it encounters throughout its life. Most scientists, based on their research, emphasise the multidimensionality of individual animal characteristics (Hunter et al, 2021;Kitajima et al, 2022). Reactivity is one of the most common signs to measure the state of a cow's body.…”