Cardiac responses to palpation per rectum in lactating and nonlactating dairy cows

Abstract

Interest in the monitoring of heart rate variability (HRV) has increased recently, as it gives more detailed and immediate information about the level of stress than traditional behavioral or hypothalamus-pituitary-adrenal measures. In this study, we evaluated heart rate (HR) and parasympathetic HRV parameters to monitor cardiac stress responses to palpation per rectum (PPR) in lactating (LACT; n = 11) and nonlactating (NLACT; n = 12) dairy cows. Heart rate and HRV were recorded from 40 min before PPR until 120 min after it was completed. Heart rate, the root mean square of successive differences (RMSSD), and the high-frequency component (HF) of HRV were analyzed by examining 5-min time windows. To compare cardiac responses to PPR between groups, changes in HR and HRV parameters were calculated as area under the curve (AUC) for LACT and NLACT cows. An immediate increase in HR was detected during PPR in both LACT (+21.4 ± 2.4 beats/min) and NLACT cows (+20.6 ± 2.3 beats/min); however, no differences were found between groups on the basis of parameters of AUC. The increase in HR in both groups along with a parallel decrease in RMSSD (LACT cows: -5.2 ± 0.4 ms; NLACT cows: -5.1 ± 0.4 ms) and HF [LACT cows: -10.1 ± 0.8 nu (where nu = normalized units); NLACT cows: -16.9 ± 1.2 nu] during PPR indicate an increase in the sympathetic, and a decrease in the parasympathetic tone of the autonomic nervous system. The increase in RMSSD (LACT cows: +7.3 ± 0.7 ms; NL cows: +17.8 ± 2.2 ms) and in HF (LACT cows: +24.3 ± 2.6 nu; NLACT cows: +32.7 ± 3.5 nu) immediately after PPR indicated a rapid increase in parasympathetic activity, which decreased under the baseline values 10 min following PPR. The amplitude and the maximum RMSSD and HF values were greater in NLACT cows than in LACT animals, suggesting a higher short-term cardiac responsiveness of NLACT cows. However, the magnitude and the duration of the stress response were greater in LACT cows, as indicated by the analysis of AUC parameters (area under the HRV response curve and time to return to baseline). Cow response to the PPR was more prominent in parasympathetic HRV measures than in HR. Based on our results, the effect of PPR on the cows' cardiac stress responses may have an impact on animal welfare on dairy farms, and investigating the effect of lactation on the cardiac stress reactions could prove useful in modeling bovine stress sensitivity. Further research is needed to find out whether the differences due to lactation are physiological or management related.

Effects of simulated sea motion on stepping behaviour in sheep

“…This coincided with a positive correlation between HR and stepping to the right side and between right limbs' forwards/backwards movements and LF/HF ratio, which suggests that the extent of these right side movements may be associated with stress (Hjortskov et al, 2004;Kovács et al 2014). Versace et al (2007) observed population level lateralities in relation to sheep preference to pass an obstacle on the right side, which they suspected arose so that the sheep could maintain the obstacle in its left eye field of vision, processed in the right brain hemisphere as for other flight/fight and reactive behaviours (Rogers, 2010;Robins and Phillips, 2010).…”

“…HF beats represent primarily parasympathetic (vagal) influences (and LF both parasympathetic and sympathetic), and a reduced HF value represents a reduced parasympathetic influence that has been associated with stress in humans (Hjortskov et al, 2004). Reduced HF has also been associated with acute stress responses in livestock, for example during rectal palpation in dairy cows (Kovács et al 2014). …”

Heart rate, heart rate variability, faecal glucocorticoid metabolites and avoidance response of dairy cows before and after changeover to an automatic milking system

“…During the AMS period, the electrodes were attached in the morning (between 06:30 and 08:00 o'clock) and removed after a 24-h recording session. The electrodes were positioned and fixed as described in our earlier studies (Kovács et al, 2013(Kovács et al, , 2014. The heart rate was recorded continuously after a 2-h acclimatisation period.…”

Modern techniques of teaching bovine rectal palpation: opportunities, benefits and disadvantages of new educational devices

“…The scale and duration of the stress reaction was larger among lactating cows than among nulligravida ones. Based on that research, the influence of PPR on stress reactions, including a cow's heart rate, may have certain impact on animal well-being on dairy farms (23,24). In case of a small percentage of cows, as a result of multiple (for example, for educational purposes) or brutal examination, rectal bleeding may occur.…”