摘要
This investigation was conducted to examine circadian and seasonal rhythms of heart rate and heart rate variability (HRV) by means of hour-by-hour recordings over 24 h in a large population of non-lactating Holstein–Friesian pregnant cows [N = 56, summer (June–July); N = 61, winter (November–December)]. Data were collected during a 5-day period from each animal. Besides parameters of cardiac autonomic function [the high-frequency (HF) component of HRV and the ratio between the low-frequency (LF) and the HF components (LF/HF ratio)], the RR triangular index and Lmax were calculated. A clear circadian profile was observed for every parameter in summer. Heart rate elevated gradually with the course of the day from 7:00 to 17:00 o'clock and then slightly decreased from 18:00 to 6:00. Sympathovagal balance shifted towards sympathetic dominance during the daytime (increased LF/HF ratio), whereas parasympathetic activity was predominant during the night (increased HF). Lmax reflected a chaotic behavior of heart rate fluctuations during the afternoon in summer. Decreased values of RR triangular index indicated a sensitive period for cows between 14:00 and 16:00 o'clock in summer. During winter, except for the RR triangular (RRtri) index reflecting a high overall variability in R–R intervals between 12:00 and 23:00 o'clock, heart rate and HRV showed no periodicity over the 24-h period. The results suggest an impaired cardiac autonomic function during daytime in summer. HF, Lmax and RRtri index showed seasonal differences for both daytime and nighttime. Heart rate was higher in summer than in winter during the daytime, whereas the LF/HF ratio was higher in winter during the nighttime. Circadian and seasonal rhythms of cardiovascular function are presumably related to the differing temperature, and animal activity associated with summer and winter. As all of the investigated parameters are commonly used in bovine HRV research, these findings have practical implications for behavioral, physiological and welfare studies on dairy cattle.
摘要译文
在一个人口众多非哺乳期的荷斯坦黑白花奶牛怀孕[N \x3d 56的按小时逐小时的录音24小时以上的手段心脏率和心脏心率变异性（HRV）的rcadian和季节节律，夏季（6鈥揓ULY）; N \x3d 61，冬季（11鈥揇月‧日）]在从各动物5天期间的数据被收集除了心脏自主函数[HRV的高频（HF）分量和低频（LF）和高频成分之间的比（LF / HF比）]的参数，在RR三角指数和L max分别观察到在夏季每个参数calculatedA明确昼夜简介心脏率从7:00一天的过程中逐步提升到17:00时，然后从18:00小幅下降至6:00交感迷走平衡白天（增加LF / HF比）时对交感神经主导地位转向，而副交感神经活动夜（增加HF）期间为优势L最大的下午在暑假期间反映心脏汇率波动的混沌行为RR下降三角指数值显示14:00，在冬季summerDuring 16:00点之间奶牛敏感时期，除了RR三角（RRtri）指数反映中的R鈥掩间隔12:00至23:00时之间高的总变异，心脏率和HRV呈现在24小时内没有周期性结果在summerHF白天建议受损的心脏自主神经功能，L最大值和RRtri指数显示这两个白天和夜间的季节差异心脏率在夏季比在白天高的冬季，而LF / HF比夜间在冬季高心血管功能的昼夜和季节节律大概涉及到的不同温度，夏季和冬季有关的动物活动由于所有被调查的参数通常在牛HRV研究中，这些发现对奶牛的行为，生理福利学实际影响
Levente Kovács[a][b]; Fruzsina Luca Kézér[a][b]; Ferenc Ruff[c]; Ottó Szenci[a][d]. Cardiac autonomic activity has a circadian rhythm in summer but not in winter in non-lactating pregnant dairy cows[J]. Physiology & Behavior, 2016,155: 56–65