Heart Rate Variability as an Indicator of Chronic Stress Caused by Lameness in Dairy Cows

Cardiac autonomic responses to transrectal examination and parlor milking of lame and nonlame dairy cows

We studied the changes in the heart rate variability of lame and nonlame dairy cows in response to transrectal examination (TRE) and parlor milking. We hypothesized that lame cows experience greater stress, manifested in heart rate variability parameters, that serves as an argument to promote more caution in the everyday handling of lame animals. In the study, we selected 55 lame (with lesions on at least one hoof, otherwise clinically healthy, with locomotion scores 4 and 5 of 5-point scores) and 55 nonlame (clinically healthy, with locomotion scores 1 and 2 of 5-point scores) cows. The heart rate, root mean square of successive beat-to-beat intervals (RMSSD), the normalized unit of the high-frequency (HF) component of the spectral analysis and Poincaré measures (SD2/SD1) were compared between lame and nonlame cows during 5 distinct stages of TRE and 7 stages of parlor milking. Heart rate, RMSSD, and SD2/SD1 showed similar patterns during TRE and milking, while HF remained fairly constant during the studied phases. No distinct RMSSD, HF, or SD2/SD1 changes were observed during the phases expected to elicit a stress response. Between-group differences were only observed in terms of HF. Baseline HF was higher in lame cows than in nonlame ones, and such a difference in direction was observed throughout the whole procedure. During milking and TRE, the heart rate, RMSSD, and SD2/SD1 values showed temporal changes in times of higher physical activity: moving to and waiting in the holding pen and moving into the milking stalls in the parlor for preparation in both lame and nonlame cows. The differences in baseline HF (normalized units) between lame and nonlame cows cannot be fully explained based on available information. The lack of a distinct, stress-related change in heart rate variability parameters in both groups can originate in methodological challenges inherent in animal heart rate variability measurements in field conditions.

Lameness in Cattle-Etiopathogenesis, Prevention and Treatment

The aim of this review was to analyse the health problem of lameness in dairy cows by assessing the health and economic losses. This review also presents in detail the etiopathogenesis of lameness in dairy cattle and examples of its treatment and prevention. This work is based on a review of available publications. In selecting articles for the manuscript, the authors focused on issues observed in cattle herds during their clinical work. Lameness in dairy cattle is a serious health and economic problem around the world. Production losses result from reduced milk yield, reduced feed intake, reproductive disorders, treatment costs, and costs associated with early culling. A significant difficulty in the control and treatment of lameness is the multifactorial nature of the disease; causes may be individual or species-specific and may be associated with the environment, nutrition, or the presence of concomitant diseases. An important role is ascribed to infectious agents of both systemic and local infections, which can cause problems with movement in animals. It is also worth noting the long treatment process, which can last up to several months, thus significantly affecting yield and production. Given the high economic losses resulting from lameness in dairy cows, reaching even >40% (depending on the scale of production), there seems to be a need to implement extensive preventive measures to reduce the occurrence of limb infections in animals. The most important effective preventive measures to reduce the occurrence of limb diseases with symptoms of lameness are periodic hoof examinations and correction, nutritional control, and bathing with disinfectants. A clean and dry environment for cows should also be a priority.

Calming Hungarian Grey Cattle in Headlocks Using Processed Nasal Vocalization of a Mother Cow

Sound analysis is an important field of research for improving precision livestock farming systems. If the information carried by livestock sounds is interpreted correctly, it could be used to improve management and welfare assessment in this field. Therefore, we hypothesized that the nasal vocalization of a mother cow could have a calming effect on conspecifics. The nasal vocalization in our study was recorded from a mother cow (not part of the test herd) while it was licking its day-old calf. The raw sound was analyzed, cleaned from noises, and the most representative vocalization was lengthened to two minutes. Thirty cows having calves were randomly selected from eighty Hungarian grey cattle cows. Two test days were selected, one week apart; the weather circumstances in both days were similar. The herd was collected in a paddock, and the test site (a restraining crate with a headlock) was 21 m away from them. The cows from the herd were gently moved to the restraining crate, and, after the installation of the headlock, Polar® heart rate monitors were fixed on the animals. The recording of the RR intervals was carried out for two minutes. On day one of the test, the processed nasal sound was played to every second cow during the heart rate monitoring. When the sound ended, the heart rate monitor was removed. On test day two, the sound and no sound treatments were switched among the participating cows. At the end of the measurement, the headlock was opened, letting the animals out voluntarily, and a flight test was performed along a 5 m distance. The time needed to pass the 5 m length was measured with a stopwatch and divided by the distance. The RR intervals were analyzed with the Kubios HRV Standard (ver. 3.5.0) software. The following data were recorded for the entire measurement: average and maximum heart rate; SD1 and SD2; pNN50; VLF, LF, and HF. The quasi-periodic signal detected in the sound analyses can hardly be heard, even when it is enhanced to the maximum. This can be considered a vibration probably caused by the basis of articulation, such as a vibration of the tongue, for example. The SD2/SD1 ratio (0.97 vs. 1.07 for the animals having no sound and sound played, respectively, p = 0.0110) and the flight speed (0.92 vs. 1.08 s/m for the animals having no sound and sound played, respectively, p = 0.0409) indicate that the sound treatment had a calming effect on the restrained cows. The day of the test did not influence any of the measured parameters; therefore, no effect of the routine was observed. The yes-no sequence of the sound treatment significantly reduced the pNN50 and flight speed values, suggesting a somewhat more positive association with the headlock and the effectiveness of the processed nasal sound. In conclusion, we have demonstrated that, by means of sound analyses, not only information about individuals and the herd can be gathered but that, with proper processing, the sound obtained can be used to improve animal welfare.

Behavior and heart rate variability after intranasal administration of oxytocin in Holstein steers

Oxytocin (OXT) is a neuropeptide that regulates memory, emotion, stress response, and behavior in the brain. In our previous study with cattle, we demonstrated the anti-stress effect of intracerebroventricularly administered OXT on the central nervous system. However, it is important to investigate the effects of this peptide after intranasal administration, as it offers convenience and non-invasiveness for practical use. Therefore, this study investigated the effects of intranasal OXT on the behavior and autonomic nervous system of Holstein steers. The experiment followed a within-subjects design, including a total of six steers. Each steer received intranasal administration of either 1 mL of saline (SAL), 100 µg OXT (OXT100), or 200 µg OXT (OXT200). However, due to some issues, the sample size for the OXT200 group was reduced to five. After these treatments, we conducted electrocardiography recordings to analyze heart rate variability (HRV) and also made behavioral observations for 90 min. OXT200 tended to increase the time spent ruminating while lying down (Steel's multiple comparison test; P=0.053). In contrast, OXT treatment did not affect HRV indices. In conclusion, the current OXT dosage did not significantly affects behavior or the autonomic nervous system. However, the observed tendency to increase rumination may suggest a central effect of OXT.

Decoding the correlation between heart activation and walking path by information-based analysis

BACKGROND

One of the important areas of heart research is to analyze heart rate variability during (HRV) walking.

OBJECTIVE

In this research, we investigated the correction between heart activation and the variations of walking paths.

METHOD

We employed Shannon entropy to analyze how the information content of walking paths affects the information content of HRV. Eight healthy students walked on three designed walking paths with different information contents while we recorded their ECG signals. We computed and analyzed the Shannon entropy of the R-R interval time series (as an indicator of HRV) versus the Shannon entropy of different walking paths and accordingly evaluated their relation.

RESULTS

According to the obtained results, walking on the path that contains more information leads to less information in the R-R time series.

CONCLUSION

The analysis method employed in this research can be extended to analyze the relation between other physiological signals (such as brain or muscle reactions) and the walking path.

Associations between cow-level parameters and heart rate variability as a marker of the physiological stress response in dairy cows

To maintain and enhance cow productivity and welfare, it is important that we can accurately assess and understand how cows respond to the physiological demands of gestation and lactation. Several methods have been developed for assessing the physiological responses to stressors and for detecting distress in cattle. Heart rate (HR) variability (HRV) is a non-invasive measure of autonomic nervous system activity and consequently a component of the physiological response to stress. In cattle, HRV has been successfully used to measure autonomic responses to a variety of health conditions and management procedures. The objectives of this study were to determine whether, among commercial Holstein Friesian cows and across farms, relationships exist between cow-level factors, HR and HRV. HRV parameters were compared with production records for 170 randomly selected, Holstein-Friesian-cows on 3 commercial dairy farms. Production data included parity, days in milk (DIM), milk yield, somatic cell count (SCC), % butterfat and protein, body condition score (BCS) and genetic indices. Fixed-effect, multivariable linear regression models were constructed to examine the association between cow-level variables and HRV parameters. Statistically significant relationships were found between HR and farm, temperature and BCS, and between HRV parameters and farm, rectal temperature, BCS, DIM, and percentage butterfat. Given the significant association between farms and several of the indices measured, it is recommended that care must be taken in the interpretation of HRV studies that are conducted on animals from a single farm. The current study indicated that within clinically normal dairy cattle HRV differed with the percentage of butterfat and BCS. Based on the relationships reported previously between HRV and stress in dairy cattle these results suggest that stress may be increased early in lactation, in cows with BCS <2.75 that are producing a high percentage of butterfat milk. Future work could focus on the physiological mechanisms through which these factors and their interactions alter HRV and how such physiological stress may be managed within a commercial farm setting.

Identification of chronic stress biomarkers in dairy cows

Stress in dairy herds can occur from multiple sources. When stress becomes chronic because of a long duration and inability of animals to adapt, it is likely to deeply affect the emotional state, health, immunity, fertility and milk production of cows. While assessing chronic stress in herds would be beneficial, no real consensus has emerged from the literature regarding the indicators of interest. The goal of this study was to compare and evaluate potential biomarkers for chronic stress after inducing stress over a 4-week period through severe overstocking, restricted access to feed and isolated unusual events. A total of 30 cows were involved in the experiment and two similar groups were constituted. Over a 4-week period, the 15 cows of the stress group were housed in overstocked conditions, with 4.6 m² per cow, including resting and feeding areas. In this area, only seven individual places at the feeding area were available for the 15 cows to generate competition for feed access. Twice during the trial and over a period of 2 h, an additional stress was induced by moving cows to an unfamiliar barn and diffusion of stressing noises (dog barking). Meanwhile, the 15 cows of the control group stayed in the original barn, with more than 10 m² per cow and more individual places at the feeding area than cow number. On a weekly basis, several variables considered as potential biomarkers for chronic stress were recorded. Collected data were analysed using single trait linear repeated mixed models. No differences were observed regarding milk yield, BW of cows or body condition score but the milk loss was more pronounced in the stress group. The activity was more heterogeneous and the rumination of cows was lower in the stress group. The heart rate was lower in the stress group and showed more heterogeneity at the end of the stress period. No differences were observed regarding salivary cortisol, blood glucose, β-endorphin, thyroxine and leucocyte profile. A higher level of hair cortisol and blood fructosamine were observed in the stress group at the end of the stress period. Regarding the practical use of the highlighted biomarkers, milk loss may be an effective and easy way to detect general problems, including stress. The blood fructosamine and the hair cortisol concentrations are promising indicators to assess chronic stress in commercial farms.

An Assessment of Stress Status in Fattening Steers by Monitoring Heart Rate Variability: A Case of Dietary Vitamin A Restriction

Heart rate variability (HRV), heart beat-to-beat variations, is a measure of cardiac autonomic functions, and HRV monitoring using sensor technology can be a non-invasive way to assess stress of animals. The objective of this study was to investigate the effect of dietary vitamin A (VA) restriction to enhance beef quality on the physiological status of fattening steers by HRV analysis. Six Japanese Black steers were equally allocated into VA-restricted (RES) and VA-supplemented (SUP) groups. The RES steers were fed VA-restricted diets from 11 to 20 months of age. The inter-beat intervals and blood VA concentration were measured at 18 and 24 months of age. HRV parameters in time, frequency, and non-linear domains were calculated using the inter-beat intervals. Blood VA concentration was significantly lower in RES steers than in SUP steers at 18 months of age (P &lt; 0.05) but did not differ between the groups at 24 months of age. The HRV analysis indicated greater sympathetic and lower parasympathetic activities in RES steers than in SUP steers (P &lt; 0.05). However, there were significant interactions of the group and age on HRV parameters (P &lt; 0.05), indicating that although RES steers at 18 months of age might suffer from slight stress, the response could recover to a level similar to SUP steers at 24 months of age by the increase in blood VA concentration.

Housing and personality effects on judgement and attention biases in dairy cows

Affective states can be inferred from responses to ambiguous and threatening stimuli, using Judgement Bias Tasks (JBTs) and Attention Bias Tasks (ABTs). We investigated the separate and interactive effects of personality and housing conditions on dairy cattle affective states. We assessed personality in 48 heifers using Open-Field, Novel-Object and Runway tests. Personality effects on responses to the JBT and to the ABT were examined when heifers were housed under reference conditions. Heifers were subsequently housed under positive or negative conditions, and housing effects on animal responses in both tasks were investigated while controlling for personality. A Principal Component Analysis revealed three personality traits labelled Activity, Fearfulness and Sociability. Under reference conditions, personality influenced heifers' responses to the JBT and to the ABT, therefore questioning the tasks' generalizability across individuals. Against expectations, housing did not influence responses to the  JBT and heifers in the negative conditions looked at the threat later than heifers in the positive or reference conditions. More research is warranted to confirm the validity and the repeatability of the JBT and of the ABT as appropriate measures of affective states in dairy cows.

Biometric Physiological Responses from Dairy Cows Measured by Visible Remote Sensing Are Good Predictors of Milk Productivity and Quality through Artificial Intelligence

New and emerging technologies, especially those based on non-invasive video and thermal infrared cameras, can be readily tested on robotic milking facilities. In this research, implemented non-invasive computer vision methods to estimate cow's heart rate, respiration rate, and abrupt movements captured using RGB cameras and machine learning modelling to predict eye temperature, milk production and quality are presented. RGB and infrared thermal videos (IRTV) were acquired from cows using a robotic milking facility. Results from 102 different cows with replicates (n = 150) showed that an artificial neural network (ANN) model using only inputs from RGB cameras presented high accuracy (R = 0.96) in predicting eye temperature (°C), using IRTV as ground truth, daily milk productivity (kg-milk-day^-1), cow milk productivity (kg-milk-cow^-1), milk fat (%) and milk protein (%) with no signs of overfitting. The ANN model developed was deployed using an independent 132 cow samples obtained on different days, which also rendered high accuracy and was similar to the model development (R = 0.93). This model can be easily applied using affordable RGB camera systems to obtain all the proposed targets, including eye temperature, which can also be used to model animal welfare and biotic/abiotic stress. Furthermore, these models can be readily deployed in conventional dairy farms.

Early Detection of Locomotion Disorders in Gilts Using a Novel Visual Analogue Scale; Associations with Chronic Stress and Reproduction

Locomotion scoring is crucial for the early detection of lameness, which reduces sow welfare and performance. Our objective was to test the effectiveness of a visual analogue scale (VAS) to measure locomotory ability (OVERALL) compared to a categorical scoring system (CAT) and to investigate associations with hair cortisol and reproductive performance. Locomotion was scored in gilts (n = 51) at service, on day 57 and day 108 of pregnancy, and at weaning, using a VAS (150 mm line: 0 mm (perfect)-150 mm (severely lame)), and a CAT (1 (perfect)-5 (severely lame)). Hair cortisol concentration was measured on day 108 of pregnancy. Reproductive performance data (parity 1-4) were acquired from farm records. VAS detected deviations from optimal locomotion more effectively than the CAT (F_3,145 = 2.70; p ≤ 0.05 versus F_3,195 = 2.45; p = 0.065). Higher OVERALL scores at service (REG = 0.003 ± 0.0012; F_1,48 = 4.25; p ≤ 0.05) and on day 57 (REG = 0.003 ± 0.0013; F_1,48 = 6.95; p ≤ 0.05) were associated with higher hair cortisol concentrations on day 108. Positive associations were detected between OVERALL at service and the number of piglets born dead (REG = 0.01 ± 0.006; F_1,36 = 4.24; p ≤ 0.05), and total born (REG = 0.1 ± 0.03; F_1,120 = 4.88; p ≤ 0.05). The VAS better facilitates early detection of lameness, which could help to prevent detrimental effects, possibly mediated by chronic stress, on reproductive performance.

Does Smart Farming Improve or Damage Animal Welfare? Technology and What Animals Want

“Smart” or “precision” farming has revolutionized crop agriculture but its application to livestock farming has raised ethical concerns because of its possible adverse effects on animal welfare. With rising public concern for animal welfare across the world, some people see the efficiency gains offered by the new technology as a direct threat to the animals themselves, allowing producers to get “more for less” in the interests of profit. Others see major welfare advantages through life-long health monitoring, delivery of individual care and optimization of environmental conditions. The answer to the question of whether smart farming improves or damages animal welfare is likely to depend on three main factors. Firstly, much will depend on how welfare is defined and the extent to which politicians, scientists, farmers and members of the public can agree on what welfare means and so come to a common view on how to judge how it is impacted by technology. Defining welfare as a combination of good health and what the animals themselves want provides a unifying and animal-centered way forward. It can also be directly adapted for computer recognition of welfare. A second critical factor will be whether high welfare standards are made a priority within smart farming systems. To achieve this, it will be necessary both to develop computer algorithms that can recognize welfare to the satisfaction of both the public and farmers and also to build good welfare into the control and decision-making of smart systems. What will matter most in the end, however, is a third factor, which is whether smart farming can actually deliver its promised improvements in animal welfare when applied in the real world. An ethical evaluation will only be possible when the new technologies are more widely deployed on commercial farms and their full social, environmental, financial and welfare implications become apparent.

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

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.

Effects of Heat Stress on Heart Rate Variability in Free-Moving Sheep and Goats Assessed With Correction for Physical Activity

Heart rate variability (HRV) is the heart beat-to-beat variation under control of the cardiovascular function of animals. Under stressed conditions, cardiac activity is generally regulated with an upregulated sympathetic tone and withdrawal of vagal tone; thus, HRV monitoring can be a non-invasive technique to assess stress level in animals especially related to animal welfare. Among several stress-induced factors, heat stress is one of the most serious causes of physiological damage to animals. The aim of this study was to assess the effects of heat stress on HRV in small ruminants under free-moving conditions. In three experimental periods (June, August, and October), inter-beat intervals in sheep and goats (three for each) in two consecutive days were measured. HRV parameters were calculated from the inter-beat interval data by three types of analyses: time domain, frequency domain, and non-linear analyses. The temperature–humidity index (THI) was used as an indicator of heat stress, and vectorial dynamic body acceleration (VeDBA) was calculated to quantify the physical activity of the animals tested. First, we investigated correlations of THI and VeDBA with HRV parameters; subsequently, THI was divided into five categories according to the values obtained (≤ 65, 65–70, 70–75, 75–80, and >80), and the effects of the THI categories on HRV parameters were investigated with and without correcting for the effects of physical activity based on the VeDBA. The results indicated that HRV significantly decreased with increasing THI and VeDBA. For non-linear HRV parameters that were corrected for the effects of physical activity, it was suggested that there would be a threshold of THI around 80 that strongly affected HRV; high heat stress can affect the autonomic balance of animals non-linearly by inducing the sympathetic nervous system. In conclusion, to assess psychophysiological conditions of unrestrained animals by HRV analysis, the confounding effect of physical activity on HRV should be minimized for a more precise interpretation of the results.

To deny, to justify, or to apologize: Do social accounts influence stress levels in the aftermath of psychological contract breach?

Background

Workplace stress carries considerable costs for the employees’ wellbeing and for the organization’s performance. Recent studies demonstrate that perceptions of psychological contract breach are a source of stress for employees. That is, when employees notice that their employer does not fulfil certain obligations, they will perceive that certain resources are threatened or lost, which in turn translates into increased stress. In this study, we zoom in on how stress unfolds in the aftermath of breach, dependent on the organization’s reaction to the breach. More specifically, we examined the influence of different types of social accounts (i.e., denial, apology, blaming and exonerating justification) on individuals’ stress resolution process using physiological (i.e., heart rate) and psychological (self-report) data.

Method

We used an experimental design in which we manipulated psychological contract breach and social account type. To test our hypotheses, we performed two sets of functional Principal Component Analyses: first to examine the effects of breach and second to examine the effects of social accounts.

Results

Our results indicate that breach elicits a physiological stress reaction, reflected in a short-lived increase in heart rate. However, no increase in the self-reported stress measure was found. Further, we did not find a significant effect of social accounts on the psychological and physiological recovery process.

Conclusions

The current research allows us to demonstrate that psychological contract breach will trigger a short-lived increase in heart rate. Further research is needed to better understand unfolding trajectories of physiological reactions to contract breach and the effect of social accounts as organizational recovery efforts.

Heart rate variability in dairy cows with postpartum fever during night phase

Autonomic nervous function evaluated by heart rate variability (HRV) and blood characteristics were compared between Holstein Friesian cows that developed postpartum fever (PF; n = 5) and clinically healthy (CH; n = 6) puerperal cows in this case-control study. A cow was defined as having PF when its rectal temperature rose to ≥39.5°C between 1 and 3 days postpartum. We recorded electrocardiograms during this period using a Holter-type electrocardiograph and applied power spectral analysis of HRV. Comparisons between the groups were analyzed by t test or Mann-Whitney U test, and the relationship between rectal temperature and each parameter was analyzed using multiple regression analysis. Heart rate was higher in PF cows than in CH cows (Mean ± SE, 103.3 ± 2.7 vs. 91.5 ± 1.7 bpm). This result suggested that PF cows had a relatively dominant sympathetic nervous function. Total (44,472 ± 2,301 vs. 55,373 ± 1,997 ms) and low frequency power (24.5 ± 3.8 vs. 39.9 ± 5.3 ms) were lower in PF cows than in CH cows. These findings were possibly caused by a reduction in autonomic nervous function. The total white blood cell count (54.3 ± 5.1 vs. 84.5 ± 6.4 ×10²/μL) and the serum magnesium (2.1 ± 0.1 vs. 2.4 ± 0.1 mg/dL) and iron (81.5 ± 8.0 vs. 134.4 ± 9.1 μg/dL) concentrations were lower and the serum amyloid A concentration (277 ± 33 vs. 149 ± 21 μg/mL) was higher in PF cows than in CH cows. These results imply that more inflammation was present in PF cows than in CH cows. Multiple regression analysis showed that both of low frequency power and concentration of serum iron were associated with rectal temperature. We found differences in changes in hematologic results, biochemical findings, and HRV patterns between PF cows and CH cows.

Claw Trimming as a Lameness Management Practice and the Association with Welfare and Production in Dairy Cows

Lameness resulting from claw lesions remains a pressing welfare issue in dairy cows. Claw trimming (CT) is a common practice for prevention and management of clinically lame cows. This review summarizes the results of studies that have investigated various claw trimming (CT) methods, their application in lameness management, and associations with the welfare and production of dairy cows. The papers included in this review fulfilled the following inclusion criteria: published in peer review journal or book chapter within the last 20 years (1999-2019), written in English, and focused on the application of CT for lameness management and the association with either welfare or production variables. Databases used included Google scholar, Web of Science and PubMed. A total of 748 records were assessed and 61 papers were eligible for inclusion and the main objectives and results were used to categorize the results under six topics: CT techniques, association between CT and claw overgrowth/specific claw lesions, timing and frequency of CT, association between CT and behavioral variables, association between CT and physiological parameters, and association between CT and production. The literature findings showed the existence of various CT methods with the common types including the Dutch Five-step, White Line, White Line Atlas, and Kansas techniques. There is data paucity on the efficacy of these techniques in lameness management; however, the slight procedural difference yields varying sole thicknesses and presentations which may influence their prophylactic use. Results regarding the impact of CT on welfare and production were discussed in relation to potential short and long-term benefits. Depending on the lesion type and severity level, CT may induce immediate painful sensation, stress, changes in lying down activities and reduction in milk yield, but the positive impacts were more evident at later stages of lactation following improvement in locomotion score. The majority of the reviewed studies were lacking a detailed description of CT techniques and claw health of the studied animals; thus, reducing the strength of demonstrating CT-related benefits. However, electronic recording of claw health data during every CT visit provides the basis for monitoring hoof health and could assist in curtailing some of these challenges. To elucidate CT-related benefits, certain areas requiring further research were highlighted such as ascertaining the appropriate timing for preventive CT and identifying cows that will benefit more from such intervention during lactation.

Cardiac vagal tone, plasma cortisol, and dehydroepiandrosterone response to an ACTH challenge in lame and nonlame dairy cows

We studied the adrenocortical and vagal tone responses to a single ACTH challenge in lame (n = 9) vs nonlame (n = 9) dairy cows. Cows were paired according to parity, days in milk, and milk yield. Plasma cortisol and dehydroepiandrosterone concentrations and cardiac vagal tone response (high-frequency component of heart rate variability) were compared after intravenous ACTH administration. Baseline, minimum or maximum, amplitude of the response and area under the response curve were compared. No difference was detected between groups in the cortisol response. Dehydroepiandrosterone was irresponsive to ACTH treatment, and concentrations did not differ between lame and nonlame cows. Vagal tone decreased in response to the ACTH treatment. High frequency component of heart rate variability was lower in the lame group at all sampling times. Lameness was associated with delayed return to baseline. We concluded that the adrenal response capacity is not influenced by lameness, which supports the concept of lameness being a chronic intermittent rather than a chronically persistent stressor. Dehydroepiandrosterone concentrations were not proven to be useful indicators of hypothalamus-pituitary axis dysfunction in cattle. A decreased vagal contribution to heart rate variability-possibly coupled with increased sympathetic modulation-was observed in lame cows, which suggests that lameness affects the mechanisms underlying the action of ACTH on cardiovascular activity.

Neuro-autonomic changes induced by remote ischemic preconditioning (RIPC) in healthy young adults: Implications for stress

The mechanisms underlying the protective effects of remote ischemic preconditioning (RIPC) are not presently clear. Recent studies in experimental models suggest the involvement of the autonomic nervous system (ANS) in cardioprotection. The aim of this study was to investigate the changes in ANS in healthy young volunteers divided into RIPC (n = 22) or SHAM (n = 18) groups. RIPC was induced by 1 cycle of 4 min inflation/5 min deflation followed by 2 cycles of 5 min inflation/5 min deflation of a cuff placed on the upper left limb. The study included analysis of heart rate (HR), blood pressure (BP), heart rate variability (HRV), measurements of microcirculation and porphyrin fluorescence in the limb before and after the RIPC. RIPC caused reactive hyperemia in the limb and reduced blood porphyrin level. A mental load (serial sevens test) and mild motor stress (hyperventilation) were performed on all subjects before and after RIPC or corresponding rest in the SHAM group. Reduction of HR occurred during the experiments in both RIPC and SHAM groups reflecting RIPC-independent adaptation of the subjects to the experimental procedure. However, in contrast to the SHAM group, RIPC altered several of the spectral indices of HRV during the serial sevens test and hyperventilation. This was expressed predominantly as an increase in power of the very low-frequency band of the spectrum, increased values of detrended fluctuation analysis and weakening of correlation between the HRV parameters and HR. In conclusion, RIPC induces changes in the activity of ANS that are linked to stress resistance.

Symposium review: Scientific assessment of affective states in dairy cattle

Affective states, which refer to feelings or emotions, are a key component of animal welfare, but these are also difficult to assess. Drawing upon a body of theoretical and applied work, we critically review the scientific literature on the assessment of affective states in animals, drawing examples where possible from research on dairy cattle, and highlighting the strengths and weaknesses of scientific methods used to assess affective states in animals. We adopt the "valence/arousal" framework, describing affect as a 2-dimensional space (with valence referring to whether an experience is positive or negative, and arousal referring to the intensity of the experience). We conclude that spontaneous physiological and behavioral responses typically reflect arousal, whereas learned responses can be valuable when investigating valence. We also conclude that the assessment of affective states can be furthered using mood assessments and that the use of drug treatments with known emotional effects in humans can be helpful in the assessment of specific affective states in animals.

Nonlinear analysis of heart rate variability for evaluating the growing pig stress response to an acute heat episode

Heart rate variability (HRV) is a proxy measure of autonomic function and can be used as an indicator of swine stress. While traditional linear measures are used to distinguish between stressed and unstressed treatments, inclusion of nonlinear HRV measures that evaluate data structure and organization shows promise for improving HRV interpretation. The objective of this study was to evaluate the inclusion of nonlinear HRV measures in response to an acute heat episode. Twenty 12- to 14-week-old growing pigs were individually housed for 7 days and acclimated to thermoneutral conditions (20.35°C ± 0.01°C; 67.6% ± 0.2% RH) before undergoing one of the two treatments: (1) thermoneutral control (TN; n = 10 pigs) or (2) acute heat stress (HS; n = 10 pigs; 32.6°C ± 0.1°C; 26.2% ± 0.1% RH). In Phase 1 of the experimental procedure (P1; 60 min), pigs underwent a baseline HRV measurement period in thermoneutral conditions before treatment [Phase 2; P2; 60 min once gastrointestinal temperature (Tg) reached 40.6°C], where HS pigs were exposed to heated conditions and TN pigs remained in thermoneutral conditions. After P2, all pigs were moved back to thermoneutral conditions (Phase 3; P3; 60 min). During each phase, Tg data were collected every 5 min and behavioural data were collected to evaluate the amount of time each pig spent in an active posture. Additionally, linear (time and frequency domain) and nonlinear [sample entropy (SampEn), de-trended fluctuation analysis, percentage recurrence, percentage determinism (%DET), mean diagonal line length in a recurrence plot] HRV measures were quantified. Heat stressed pigs exhibited greater Tg (P = 0.002) and spent less time in an active posture compared to TN pigs during P2 (P = 0.0003). Additionally, low frequency to high frequency ratio was greater in HS pigs during P3 compared to TN pigs (P = 0.02). SampEn was reduced in HS pigs during P2 (P = 0.01) and P3 (P = 0.03) compared to TN pigs. Heat stressed pigs exhibited greater %DET during P3 (P = 0.03) and tended to have greater %DET (P = 0.09) during P2 than TN pigs. No differences between treatments were detected for the remaining HRV measures. In conclusion, linear HRV measures were largely unchanged during P2. However, changes to SampEn and %DET suggest increased heat stress as a result of the acute heat episode. Future work should continue to evaluate the benefits of including nonlinear HRV measures in HRV analysis of swine heat stress.

Associating cow characteristics with mobility scores in pasture-based dairy cows

The quality of dairy cow mobility can have significant welfare, economic, and environmental consequences that have yet to be extensively quantified for pasture-based systems. The objective of this study was to characterize mobility quality by examining associations between specific mobility scores, claw disorders (both the type and severity), body condition score (BCS), and cow parity. Data were collected for 6,927 cows from 52 pasture-based dairy herds, including mobility score (0 = optimal mobility; 1, 2, or 3 = increasing severities of suboptimal mobility), claw disorder type and severity, BCS, and cow parity. Multinomial logistic regression was used for analysis. The outcome variable was mobility score, and the predictor variables were BCS, type and severity of claw disorders, and cow parity. Three models were run, each with 1 reference category (mobility score 0, 1, or 2). Each model also included claw disorders (overgrown claw, sole hemorrhage, white line disease, sole ulcer, and digital dermatitis), BCS, and cow parity as predictor variables. The presence of most types of claw disorders had odds ratios >1, indicating an increased likelihood of a cow having suboptimal mobility. Low BCS (BCS <3.00) was associated with an increased risk of a cow having suboptimal mobility, and relatively higher parity was also associated with an increased risk of suboptimal mobility. These results confirm an association between claw disorders, BCS, cow parity, and dairy cow mobility score. Therefore, mobility score should be routinely practiced to identify cows with slight deviations from the optimal mobility pattern and to take preventive measures to keep the problem from worsening.

Short communication: Assessment of disbudding pain in dairy calves using nonlinear measures of heart rate variability

The purpose of this study was to evaluate whether pain-related stress caused by disbudding could be detected using nonlinear measures of heart rate variability (HRV). Twenty-five female Holstein calves (4-7 wk of age) were randomly assigned to 1 of 3 treatments: (1) sham disbud (SHAM; n = 9), (2) disbud with lidocaine-meloxicam pain mitigation (MED; n = 8), or (3) disbud without pain mitigation (NoMED; n = 8). Heart rate variability (sample entropy, percentage determinism, percentage recurrence, or mean length of diagonal lines in a recurrence plot) was recorded on d -1, 0, 1, 3, and 5 relative to the experimental procedure, with disbudding taking place on d 0. The short-term detrended fluctuation analysis scaling exponent was greater in MED calves than in SHAM calves, indicating a greater stress response to the disbudding procedure regardless of pain mitigation. These results indicate that calves in the MED group may have experienced pain-related stress as a result of the disbudding procedure. The remaining nonlinear HRV measures did not differ by treatment. Future research on this topic should address additional potential confounding factors, such as the effect of pain-mitigating drugs on autonomic function or the influence of the autonomic nervous system on wound healing, that may prohibit HRV measurement as an indicator of disbudding pain severity.

Computer vision and remote sensing to assess physiological responses of cattle to pre-slaughter stress, and its impact on beef quality: A review

Pre-slaughter stress is well-known to affect meat quality of beef carcasses and methods have been developed to assess this stress. However, development of more practical and less invasive methods are required in order to assess the response of cattle to pre-slaughter stressors, which will potentially also assist with the prediction of beef quality. This review outlines the importance of pre-slaughter stress as well as existing and emerging technologies for quantification of the pre-slaughter stress. The review includes; i) indicators of meat quality and how they are affected by pre-slaughter stress in cattle, ii) contact techniques that have been commonly used to measure stress indicators in animals, iii) remotely sensed imagery techniques recently used as non-invasive methods to monitor physiological and behavioural parameters and iv) potential implementation of remotely sensed imagery data to perform contactless assessment of physiological measurements, which could be related to the pre-slaughter stress, as well as to the indicators of beef quality. Relevance to industry, conclusions and recommendations for research are included.

Preventing ectoparasite infestations reduces glucocorticoid concentrations in the hair of cows - short communication

The aim of this study was to compare hair corticosteroid concentrations in ectoparasiticide-treated (n = 10) and non-treated (n = 12) Holstein cows. Animals in the treated group received cyfluthrin three times, on days 0, 28 and 56 of the experiment. Hair samples were collected from all cows on days 0, 21, 42, 63, and 84 of the experiment for the determination of cortisol and corticosterone concentrations using immunoassays. The respective hair cortisol concentrations in the treated group averaged 209.78, 165.10, 260.78, 177.44 and 183.11 ng/g, while in the non-treated group hair cortisol concentrations averaged 172.58, 243.58, 309.73, 199.75 and 207.09 ng/g. These results indicate that the control of ectoparasites reduced hair cortisol levels in dairy cows. The respective hair corticosterone concentrations in the treated group averaged 19.06, 22.95, 21.95, 21.60 and 24.84 ng/g and in the non-treated group the hair corticosterone concentrations averaged 17.28, 21.94, 34.05, 26.27 and 26.91 ng/g. The results suggest that longterm stress can be estimated better by the determination of hair cortisol rather than corticosterone concentrations.

Use of behavioural and physiological responses for scoring sound sensitivity in dogs

Sound sensitive dogs have exaggerated responses to sound stimuli that can negatively impact the welfare of the dog. Behavioural reactions combined with the response to sound involve a marked autonomic imbalance towards sympathetic predominance and release of cortisol. The purpose of the present study was to evaluate, in the laboratory, the cardiac autonomic modulation using heart rate variability (HRV) analysis, serum cortisol levels and behavioural parameters in response to sounds of fireworks in dogs with a history of sensitivity to fireworks. Based on these data, and combining qualitative measures and categorical measures, we propose one short and one full index of sound sensitivity in dogs. Six privately owned dogs with no history and another twelve dogs with a history of sound sensitivity to fireworks were used. The sound stimulus consisted of a standardised recording of fireworks (180-seconds long) with a peak intensity of 103–104 dB. The cardiac intervals were recorded using a frequency meter (Polar® RS800CX model) to evaluate the HRV, and the acquired data were processed using CardioSeries 2.4.1 software. Twenty-one behavioural parameters were analysed quantitatively by time, frequency or categorically by scores and were grouped in behavioural categories of arousal, fear, relaxation and “other”. Sound sensitive dogs had exacerbated autonomic responses to the sound stimulus in the laboratory compared to non-sensitive dogs, with higher LF/HF ratios suggesting autonomic imbalance towards sympathetic predominance, but the cortisol levels were similar between the sensitive and non-sensitive dogs. Sound sensitive dogs showed pronounced responses for the parameters: alert and attention, search sound, startle, trembling, hiding, run away and less intense responses for the parameters rest and wink/sleep. Furthermore, the behavioural categories of arousal, fear, relaxation (lack of) and LF/HF were correlated to the caregiver’s perception of the sound sensitivity of the dogs. Not only the short index for sound sensitivity (behavioural categories arousal, fear and relaxation, and LF/HF ratio) but also the full index for sound sensitivity (all behavioural categories, LF/HF and cortisol levels) was highly correlated to sound fear response at home. These indexes can contribute to the development of strategies to treat sound sensitive dogs.

Dairy cows - an opportunity in the research field of non-genetic inheritance?

More than 1 billion cattle are raised annually for meat and milk production. Dairy cows are repeatedly impregnated and separated from their calves, usually within the first 24 h after birth. Here, I suggest that dairy cows undergo a procedure comparable to the 'Maternal separation combined with unpredictable maternal stress' paradigm (MSUS), which is used to study the non-genetic inheritance (NGI) of phenotypes in rodents. I discuss what research on dairy cows may bring to the research field of NGI. The resulting research findings are likely to have benefits to our understanding of MSUS, NGI and consumer safety.

Effect of physical activity on cardiac autonomic function of dairy cows on commercial dairy farms

Interbeat interval data were collected from 219 Holstein cows in 2 smaller-scale farms and 3 larger-scale farms to investigate the effects of posture (standing vs. lying), rumination (rumination vs. no rumination) and feeding on baseline values of heart rate (HR) and heart rate variability (HRV) parameters reflecting vagal and sympathetic activity. A General Linear Model was used for detecting factors (parity, milking technology, herd size) having possible effects on HRV calculated for undisturbed lying posture. Basal values of cardiac parameters were also compared between larger and smaller-scale farms. Neither parity nor milking technology affected HRV parameters. Sympathetic activity increased in the order of lying, ruminating when lying, standing, ruminating when standing and feeding on both sizes of farms. Vagal activity decreased in that order in both lower- and larger-scale farms. Rumination caused an increase in HR and a decrease in vagal tone in both lower- and larger-scale farms and an increase in sympathetic activity during lying in both farm sizes. Basal vagal activity was lower in larger-scale farms compared to smaller-scale farms, while greater sympathetic activity was found in cows housed on larger-scale farms. Our findings demonstrate that reference values of HRV parameters in lactating dairy cows cannot be generally defined for Holstein cattle as they are affected by physical activity and herd size. Higher HR and sympathetic activity at rest in larger-scale farms compared to farms with lower cow population might be associated with higher levels of social stress and therefore should be considered as a potential welfare concern.

Tech-Savvy Beef Cattle? How Heifers Respond to Moving Virtual Fence Lines

Simple Summary

Physical fences are not always possible, thus automated technology called “virtual fencing” provides a potential solution. Virtual fencing uses Global Positioning System (GPS) technology and animals wear collar devices. As animals approach the virtual fence line, the collar emits an audio tone; if the animals walk further forward, they receive an electrical stimulus. If the animal turns around after the audio tone, they receive no electrical stimulus. However, no studies to date have looked at how animals respond when virtual fences have moved to different paddock locations. Virtual boundaries were set up to restrict six beef cattle wearing collars to different paddock areas. Within a few days, the animals were able to avoid the electrical stimulus by learning to turn away from the fence when they heard the audio tone. Over several weeks, the virtual fence was moved to three different locations within the paddock, and the animals rapidly learned it had moved, turning away at the audio tone the majority of the time. This shows that animals can learn the different collar signals and avoid moving virtual boundaries via the audio tone. The application of virtual fencing to farms enables improved animal management and animal exclusion from environmentally sensitive areas.

Abstract

Global Positioning System (GPS)-based virtual fences offer the potential to improve the management of grazing animals. Prototype collar devices utilising patented virtual fencing algorithms were placed on six Angus heifers in a 6.15 hectare paddock. After a “no fence” period, sequential, shifting virtual fences restricted the animals to 40%, 60%, and 80% of the paddock area widthways and 50% lengthways across 22 days. Audio cues signaled the virtual boundary, and were paired with electrical stimuli if the animals continued forward into the boundary. Within approximately 48 h, the cattle learned the 40% fence and were henceforth restricted to the subsequent inclusion zones a minimum of 96.70% (±standard error 0.01%) of the time. Over time, the animals increasingly stayed within the inclusion zones using audio cues alone, and on average, approached the new fence within 4.25 h. The animals were thus attentive to the audio cue, not the fence location. The time spent standing and lying and the number of steps were similar between inclusion zones (all p ≥ 0.42). More lying bouts occurred at the 80% and lengthways inclusion zones relative to “no fence” (p = 0.04). Further research should test different cattle groups in variable paddock settings and measure physiological welfare responses to the virtual fencing stimuli.

Reminder: RMSSD and SD1 are identical heart rate variability metrics

Assessment of heart rate variability (HRV) is a common approach to examine cardiac autonomic nervous system modulation that has been employed in a variety of settings. Frequently, both the root mean square of successive differences (RMSSD) and SD1, which is a Poincaré plot component, have been used to quantify short-term heart rate variability. It is not typically appreciated, however, that RMSSD and SD1 are identical metrics of HRV. As a reminder to clinicians and researchers who use and study HRV, we show both empirically and mathematically that RMSSD and SD1 are identical metrics. Because the homology between RMSSD and SD1 is not commonly known, the inclusion of both measures has been reported in many recent publications. The inappropriate use of such redundant data may affect the interpretation of HRV studies. Muscle Nerve 56: 674-678, 2017.

Expression of heat-shock protein 72 mRNA in relation to heart rate variability of Sahiwal and Karan-Fries in different temperature-humidity indices

AIM

To investigate the effect of temperature-humidity index (THI) on the expression pattern of heat-shock protein 72 (HSP72) mRNA of Sahiwal and Karan-Fries (KF) cattle in different THIs.

MATERIALS AND METHODS

Five different periods of a year were selected based on combinations of T_max/T_min, viz., P1: <20°C/<10°C; P2: >20°C/<10°C, P3: <30°C/<15°C; P4: >35°C/<20°C, and P5: >35°C/>20°C. The THI was calculated from the records of temperature and relative humidity in different periods. Heart rate variability (HRV) was calculated from electrocardiogram records in different periods. HSP72 mRNA expression was estimated by reverse transcription polymerase chain reaction.

RESULTS

The THI recorded during P1, P2, P3, P4, and P5 were 55.5, 60.3, 70.1, 74.5, and 79.0, respectively. THI in P4 and P5 were stressful to animals. HSP72 mRNA expression increased during cold stress in P1 in Sahiwal and heat stress in P4 and P5 in both Sahiwal and KF. Sahiwal maintained increased HSP72 mRNA expression longer than KF without causing a significant change in HRV.

CONCLUSION

Both low THI in winter and high THI in summer increased HSP72 mRNA of Sahiwal and KF without significant change in HRV. Thermotolerance of Sahiwal could be due to the maintenance of higher HSP72 expression longer than KF in prolonged heat stress in summer.

Timing of obstetrical assistance affects peripartal cardiac autonomic function and early maternal behavior of dairy cows

Peripartal autonomic nervous system function and early maternal behavior were investigated in 79 multiparous Holstein-Friesian cows. Animals were allocated into four groups based on the technology of calving management: 1) unassisted calving in a group pen (UCG; N=19), 2) unassisted calving in an individual pen (UCI; N=21), 3) assisted calving with appropriately timed obstetrical assistance (ACA; N=20), and 4) assisted calving with premature obstetrical assistance (ACP; N=19). Heart rate, the high frequency (HF) component of heart rate variability (HRV) as a measure of vagal activity and the ratio between the low frequency (LF) and HF components (LF/HF ratio) as a parameter of sympathetic nervous system activity were calculated. Heart rate and HRV parameters were presented as areas under the curves (AUC) for the following periods: 1) prepartum period (between 96h before the onset of calving restlessness and the onset of restlessness), 2) parturition (between the onset calving restlessness and delivery), and 3) postpartum period (during a 48-h period after delivery). Pain-related behaviors were recorded during parturition (i.e., the occurrence of vocalization and stretching the neck towards the abdomen) and during a 2-h observation period after calving (i.e., the occurrence of vocalization, stretching the neck towards the abdomen and the duration of standing with an arched back). Early maternal behavior was observed during the first 2h following calving as follows: 1) latency and duration of sniffing calf's head/body, and 2) latency and duration of licking calf's head/body. No difference was found across groups in autonomic function before the onset of calving restlessness. Area under the heart rate curve was higher in ACP cows during parturition (39.6±2.5beats/min×h) compared to UCG, UCI and ACA animals (AUC=13.1±0.9beats/min×h, AUC=22.3±1.4beats/min×h and AUC=25.0±2.1beats/min×h, respectively). Area under the heart rate curve did not differ across the UCG, UCI and ACA groups during the postpartum period (AUC=65.2±16.7beats/min×h, AUC=58.0±14.2beats/min×h and AUC=62.9±12.1beats/min×h, respectively) but it was higher in ACP cows compared to the former groups (AUC=269.1±36.3beats/min×h). During parturition, area under the HF curve reflected a lower vagal tone (AUC=-30.5±1.6n.u.×h) in cows with premature obstetrical assistance than in animals that calved individually without farmer assistance (AUC=2.7±0.4n.u.×h) or with appropriately timed assistance (AUC=3.2±1.2n.u.×h). During parturition, LF/HF ratio showed greater sympathetic activity in ACP cows than in animals from any other group. Area under the HF curve was similar across UCG, UCI and ACA cows (AUC=-232.1±42.0n.u.×h, AUC=-163.4±35.6n.u.×h and AUC=-331.4±56.2n.u.×h, respectively) during the postpartum period and was the lowest in ACP cows (AUC=-1025.6±44.2n.u.×h) reflecting a long-term stress load in the latter group. During parturition, both vocalization and stretching the neck towards the abdomen occurred more often in UCG cows than in cows from any other groups, and the incidence of both behaviors was statistically higher in ACP cows than in UCI and ACA animals. There were no significant differences across groups in these behaviors during the 2-h postpartum observation. UCG cows had a shorter latency and a longer duration of maternal grooming during the first 2h following delivery compared to any other groups. UCI and ACA dams spent more time with licking the calf within the 2-h period after calving and had a shorter latency to sniff and lick the offspring compared to cows that received premature assistance. Group calving is less stressful for cows than calving in an individual pen either with or without obstetrical assistance. Calving in a group or with appropriately timed farmer assistance supports the expression of early maternal behavior and lead to a rapid postpartum recovery of the autonomic nervous system. Premature obstetrical assistance means stress for cows during parturition, leads to a prolonged postpartum recovery of the autonomic nervous system and inhibits the expression of early maternal behavior.

Behavioural and physiological measures indicate subtle variations in the emotional valence of young pigs

In the study of animal emotions, emotional valence has been found to be difficult to measure. Many studies of farm animals' emotions have therefore focussed on the identification of indicators of strong, mainly negative, emotions. However, subtle variations in emotional valence, such as those caused by rather moderate differences in husbandry conditions, may also affect animals' mood and welfare when such variations occur consistently. In this study, we investigated whether repeated moderate aversive or rewarding events could lead to measurable differences in emotional valence in young, weaned pigs. We conditioned 105 female pigs in a test arena to either a repeated startling procedure (sudden noises or appearances of objects) or a repeated rewarding procedure (applesauce, toy and straw) over 11 sessions. Control pigs were also regularly exposed to the same test arena but without conditioning. Before and after conditioning, we measured heart rate and its variability as well as the behavioural reactions of the subjects in the test arena, with a special focus on detailed acoustic analyses of their vocalisations. The behavioural and heart rate measures were analysed as changes compared to the baseline values before conditioning. A limited number of the putative indicators of emotional valence were affected by the conditioning. We found that the negatively conditioned pigs showed changes that were significantly different from those in control pigs, namely a decrease in locomotion and an increase in standing. The positively conditioned pigs, however, showed a stronger increase in heart rate and a smaller decrease in SDNN (a heart rate variability parameter indicating changes in autonomic regulation) compared to the controls. Compared to the negatively conditioned pigs, the positively conditioned pigs produced fewer vocalisations overall as well as fewer low-frequency grunts but more high-frequency grunts. The low-frequency grunts of the negatively conditioned pigs also showed lower frequency parameters (bandwidth, maximum frequency, 25% and 50% quartiles) compared to those of the positively conditioned pigs. In any of the statistically significant results, the conditioning accounted for 1.5-11.9% of variability in the outcome variable. Hence, we conclude that repeated moderate aversive and rewarding events have weak but measurable effects on some aspects of behaviour and physiology in young pigs, possibly indicating changes in emotional valence, which could ultimately affect their welfare. The combination of ethophysiological indicators, i.e., the concurrent examination of heart rate measures, behavioural responses and especially vocalisation patterns, as used in the current study, might be a useful way of examining subtle effects on emotional valence in further studies.

Associations between Heart Rate Variability Parameters and Housing- and Individual-Related Variables in Dairy Cows Using Canonical Correspondence Analysis

We investigated the associations between heart rate variability (HRV) parameters and some housing- and individual-related variables using the canonical correspondence analysis (CCOA) method in lactating Holstein-Friesian dairy cows. We collected a total of 5200 5-min interbeat interval (IBI) samples from 260 animals on five commercial dairy farms [smaller-scale farms with 70 (Farm 1, n = 50) and 80 cows per farm (Farm 2, n = 40), and larger-scale farms with 850 (Farm 3, n = 66), 1900 (Farm 4, n = 60) and 1200 (Farm 5, n = 45) cows. Dependent variables included HRV parameters, which reflect the activity of the autonomic nervous system: heart rate (HR), the root mean square of successive differences (RMSSD) in IBIs, the standard deviation 1 (SD1), the high frequency (HF) component of HRV and the ratio between the low frequency (LF) and the HF parameter (LF/HF). Explanatory variables were group size, space allowance, milking frequency, parity, daily milk yield, body condition score, locomotion score, farm, season and physical activity (lying, lying and rumination, standing, standing and rumination and feeding). Physical activity involved in standing, feeding and in rumination was associated with HRV parameters, indicating a decreasing sympathetic and an increasing vagal tone in the following order: feeding, standing, standing and rumination, lying and rumination, lying. Objects representing summer positioned close to HR and LF and far from SD1, RMSSD and HF indicate a higher sympathetic and a lower vagal activity. Objects representing autumn, spring and winter associated with increasing vagal activity, in this order. Time-domain measures of HRV were associated with most of the housing- and individual-related explanatory variables. Higher HR and lower RMSSD and SD1 were associated with higher group size, milking frequency, parity and milk yield, and low space allowance. Higher parity and milk yield were associated with higher sympathetic activity as well (higher LF/HF), while individuals with lower locomotion scores (lower degree of lameness) were characterized with a higher sympathetic and a lower vagal tone (higher HR and LF/HF and lower RMSSD and SD1). Our findings indicate that the CCOA method is useful in demonstrating associations between HRV and selected explanatory variables. We consider physical activity, space allowance, group size, milking frequency, parity, daily milk yield, locomotion score and season to be the most important variables in further HRV studies on dairy cows.

Effects of Effortful Swallow on Cardiac Autonomic Regulation

Swallowing-induced changes in heart rate have been recently reported. However, it is not apparent the responses of heart rate variability (HRV) elicited by effortful swallow maneuver. We investigated the acute effects of effortful swallowing maneuver on HRV. This study was performed on 34 healthy women between 18 and 35 years old. We assessed heart rate variability in the time (SDNN, RMSSD, and pNN50) and frequency (HF, LF, and LF/HF ratio) domains and, visual analysis through the Poincaré plot. The subjects remained at rest for 5 min during spontaneous swallowing and then performed effortful swallowing for 5 min. HRV was analyzed during spontaneous and effortful swallowing. We found no significant differences for SDNN, pNN50, RMSSD, HF in absolute units (ms(2)). There is a trend for increase of LF in absolute (p = 0.05) and normalized (p = 0.08) units during effortful swallowing. HF in normalized units reduced (p = 0.02) during effortful swallowing and LF/HF ratio (p = 0.03) increased during effortful swallowing. In conclusion effortful swallow maneuver in healthy women increased sympathetic cardiac modulation, indicating a cardiac overload.

Cardiac autonomic activity has a circadian rhythm in summer but not in winter in non-lactating pregnant dairy cows

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 24h 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.