Interpretation of behavioural reactions of sheep towards fear-eliciting situations

Behavioural reactivity testing in sheep indicates the presence of multiple temperament traits

Temperament in sheep is commonly presented as unidimensional, with a 'nervous' temperament indicative of fear and reactivity towards humans and novel environments. However, temperament is multidimensional, with some traits expressed only under certain conditions (context-specific). There is evidence that a common temperament test in sheep, the isolation-box (IB), measures level of activity and not fearfulness as intended, and that behaviours measured in the IB test are indicative of different traits. To investigate this, 16 behavioural responses to a human, to being startled, and to confinement (IB test) were measured in 89 lambs, twice, three months apart. Our results agree with previous studies that vocalisations in all tests and locomotion in two, show high repeatability over time. A principal component analysis identified that vocalisations are domain-general, and are indicative of the trait 'sociability', however locomotion is context-specific' and captures the traits 'exploration-avoidance', 'boldness-shyness' and 'general activity'. A cluster analysis identified four behavioural profiles that indicate the trait 'boldness-shyness' captures reactivity towards humans. This suggests the IB test, which measures 'general activity', is unsuitable for measuring reactivity towards humans in sheep, and that when studying the impact of temperament on other factors, multiple conditions should be used when identify temperament traits.

Intranasal oxytocin affects the stress response to social isolation in sheep

Oxytocin (OT) is a neuropeptide hormone that modulates several social behaviors and can affect the anxiety and stress response. The aim of this study was to determine if administration of intranasal OT affects the stress response to social isolation in sheep. Twenty adult Merino ewes were assigned to two groups; 1) Control group (CG, n = 10), which received an intranasal administration of isotonic saline and 2) Oxytocin-treated group (OTG, n = 10), which received an intranasal administration of OT (24 IU) 40 min before the animals were placed in the social isolation test. During the social isolation test (10 min), the behavior of the sheep was recorded, and blood samples were obtained before and after the test for the determination of cortisol, glucose and serum proteins, and heart rate and surface temperature were recorded. The OTG ewes had a higher cortisol concentration (P = 0.04) after social isolation, tended to vocalize more (P = 0.06) during isolation, and tended to have lower globulin concentrations (P = 0.10) than the CG ewes. Contrary to what we expected, the administration of intranasal OT increased the stress response to social isolation in ewes, which was evidenced by endocrine (greater increase in cortisol concentration), physiological (a tendency to present lower concentration of globulins in blood) and behavioral (a tendency to vocalize more) indicators. This study suggests that the administration of intranasal OT increased the stress response to isolation possibly by strengthening the social bond among ewes.

Impact of shearing sheep on feeding and behaviour during the pre-embarkment feedlot phase of live export

Context Shearing is a management procedure that can induce stress, and is one that sheep often undergo on-farm and/or at registered premises during the pre-embarkation phase of live export. Aim As inanition is one of the largest causes of death during sea transport and can result from sheep experiencing stress, whether shearing results in behavioural changes and stress before boarding a vessel needs to be determined. Methods A total of 600 merino wethers sourced from one farm were housed at registered pre-embarkment premises, where they were split between two adjacent pens. The wethers were further split into the six treatment groups (unshorn, and sheep shorn on Days 1, 2, 3, 4 or 5) with 50 sheep per treatment, per pen. All wethers were fitted with radio frequency identification tags that were used to record animal presence at feed and water troughs, and coloured ear tags to visually identify their treatment group. Temperature and humidity sensors were placed on the outside of each pen to record environmental conditions throughout the 13-day study. Body condition scores for each wether were recorded at the beginning and end of the study. Four portable cameras were placed at a corner of each pen, allowing behaviour states (standing, lying or locomotion) of the wethers to be recorded on Days 1, 2, 3, 4, 5 and 13 of the study. Key results Shorn treatment groups were observed to spend more time standing (F5,5 = 6.63, P = 0.029) and less time lying (F23,23 = 2.48, P = 0.017). The control group spent more time at water troughs from Day 4 to 12 (F5,55 = 3.98, P < 0.01), whereas all groups were recorded as spending more time at the feed trough on Day 5 (F5,55 = 2.78, P < 0.001). Conclusions A lack of variation in behavioural states between the treatments and no change in time spent feeding throughout the study suggest that the procedure of shearing within the first 5 days at the pre-embarkation facility had no impact on behaviour of these sheep. Implications These results assist the industry in ensuring best management practices are implemented.

Stress-Induced Immunomodulation in Low and High Reactive Sheep

Simple Summary

Proper functioning of the immune system is fundamental to maintain animal health; however, several factors can modulate an animal’s immune system, including stress. Farm animals can experience multiple stressors throughout their lifetime, therefore there is a need to know how stress can impact their immune response. Moreover, temperament can affect how an animal responds to a stressor, both behaviorally and physiologically. CarLA is a protective antigen against gastrointestinal nematodes; we wanted to evaluate if there was a relationship between stress and temperament on the CarLA response in ewes. We found that both a 0.5 h and 23 h stressor appeared to have an immunosuppressive effect on CarLA IgA but not total IgA concentrations in ewes and there was some indication that CarLA concentrations were also affected by ewe temperament. More research is needed to understand what these immunosuppressive effects of stress on CarLA IgA concentrations mean in relation to sheep immunity to parasitism using farm relevant stressors.

Abstract

The objective of this study was to investigate the relationship between stress and temperament on the humoral immune response of ewes. Eighty ewes were allocated to one of four treatment groups in a 2 × 2 factorial design (n = 20 ewes/treatment): low (LR) and high (HR) reactive ewes were either exposed to no stress (CON) or were visually isolated (STRESS). Ewes remained in treatment pens for 23 h: heart rate was measured continuously, and saliva samples were collected prior to testing and at 0.5 h and 23 h for measurement of cortisol, CarLA IgA and total IgA concentrations. After the first 0.5 h, heart rate was elevated, and cortisol concentrations tended to be higher, whereas CarLa IgA concentrations were lower in STRESS than CON ewes. Similarly, after 23 h, cortisol concentrations remained elevated and CarLA IgA concentrations remained lower in STRESS than CON ewes. Interestingly, total IgA concentrations were not influenced by a 0.5 h or 23 h stressor. Overall, CarLA IgA concentrations were lower in HR than LR ewes at 0.5 h, but there was no significant stress × temperament interaction. Therefore, stress appears to have an immunosuppressive effect on CarLA IgA but not total IgA concentrations in ewes.

Thermography as a Non-Invasive Measure of Stress and Fear of Humans in Sheep

Simple Summary

The ability to non-invasively measure fear is an essential component of animal welfare assessment. Infrared thermography (IRT) was used to obtain images from five Sarda breed ewes during restraint and immediately after two voluntary animal approach (VAA) tests. Our preliminary results suggest that IRT, combined with behavioral data, is a non-invasive technique that can be useful to assess stress and infer about negative emotions in sheep.

Abstract

No data have been published on the use of infrared thermography (IRT) to evaluate sheep emotions. We assessed whether this technique can be used as a non-invasive measure of negative emotions. Two voluntary animal approach (VAA) tests were conducted (and filmed) on five ewes before and after being restrained. The restraining process was performed by a handler for five minutes. IRT was used during restraint and the VAA tests. The lacrimal caruncle temperature was significantly higher during restraint and in the VAA test after the restraint compared with the VAA test before the restraint (Wilcoxon’s test; p = 0.04). The latency period until first contact was longer in the second VAA test (132 s) than in the first one (60 s). Our preliminary results suggest that IRT, combined with behavioral data, is a non-invasive technique that can be useful to assess stress and infer about negative emotions in sheep.

First evidence of neuronal connections between specific parts of the periaqueductal gray (PAG) and the rest of the brain in sheep: placing the sheep PAG in the circuit of emotion

The periaqueductal gray (PAG) is a mesencephalic brain structure organised in subdivisions with specific anatomical connections with the rest of the brain. These connections support the different PAG functions and especially its role in emotion. Mainly described in territorial and predatory mammals, examination of the PAG connections suggests an opposite role of the ventral and the dorsal/lateral PAG in passive and active coping style, respectively. In mammals, the organisation of PAG connections may reflect the coping style of each species. Based on this hypothesis, we investigated the anatomical connections of the PAG in sheep, a gregarious and prey species. Since emotional responses expressed by sheep are typical of active coping style, we focused our interest on the dorsal and lateral parts of the PAG. After injection of fluorogold and fluororuby, the most numerous connections occurred with the anterior cingulate gyrus, the anterior hypothalamic region, the ventromedial hypothalamic nucleus and the PAG itself. Our observations show that the sheep PAG belongs to the neuronal circuit of emotion and has specific parts as in other mammals. However, unlike other mammals, we observed very few connections between PAG and either the thalamic or the amygdalar nuclei. Interestingly, when comparing across species, the PAG connections of sheep were noticeably more like those previously described in other social species, rabbits and squirrel monkeys, than those in territorial species, rats or cats.

A protocol of human animal interaction to habituate young sheep and goats for behavioural studies

Animal habituation is key to obtain reliable data on behavioural studies but detailed procedures to achieve it are scarce. This study designed a set of actions to habituate sheep and goats to human observers. Pelibuey sheep (n = 15) and Criollo goats (n = 10) were classified as (a) avoider, flight from human interaction, or (b) follower, seek human interaction. Habituation was measured by the reduction of flight distance by avoiders, or number of followers in the presence of observers. The habituation protocol consisted of a gradually increased series of five manoeuvres, either challenge (for avoiders) or evasion (for seekers), performed first inside a pen and subsequently in a grass paddock. Habituation was considered successful when animals could be observed from a 1-m distance without flight or following the observer. In the pen, habituation took 12 and 13 days for sheep and goats, respectively. Meanwhile, in the grass paddock habituation took 10 days, for both species. The number of challenge and evasion series was negatively correlated with the flight distance in sheep and with the number of followers in goats. This protocol is simple and practical to implement and enables animal habituation for behavioural studies.

Using Longitudinal Assessment on Extensively Managed Ewes to Quantify Welfare Compromise and Risks

Simple Summary

Sheep managed extensively can be exposed to several welfare challenges during the year, and the risk of some diseases can increase in warmer and wetter seasons. In this study, the welfare of Merino ewes was examined over a calendar year. The welfare of these animals, kept on a single farm with consistent management, varied substantially. Overall, the largest number of ewes experienced compromise and risk to welfare at weaning, indicating that this was the most vulnerable time. The main welfare issues identified were under and over feeding, ewe mortality, lameness, ecto-parasites (flystrike) and mastitis, all of which could be improved by modifying management practices, such as improved nutritional management and monitoring and better tail docking procedures. Future research must consider that significant variation in the on-farm welfare of ewes occurs during a calendar year, which needs to be accounted for when conducting on-farm assessments.

Abstract

This study examined variation in the welfare of extensively managed ewes and potential welfare risks. A total of 100 Merino ewes (aged 2–4 years) were individually identified and examined at three key stages: pregnancy, lactation and weaning. Eight animal-based welfare measures were used to assess welfare: flight distance, body condition score (BCS), fleece condition, skin lesions, tail length, dag score, lameness and mastitis. Data were analysed by ANOVA and McNemar’s statistics. Overall, the average BCS of the group was in agreement with industry recommendations. However, a number of animals were classified with inadequate condition (either too thin or too fat) across the three observation periods. The presence of heavy dags was greatest at mid-lactation (87%, P < 0.0001), lameness was greatest at weaning (14%, P = 0.01), clinical mastitis was 1% annually, and five ewes were lost from the study. Ewes had better health at mid-pregnancy compared to mid-lactation and weaning. The main welfare issues identified were under and over feeding, ewe mortality, lameness, ecto-parasites (flystrike) and mastitis, all of which have the potential to be reduced with improved management practices. Future welfare assessment programs must consider that significant variation in on-farm welfare will occur in extensively managed systems and this needs to be accounted for when evaluating farms.

Social stress as a cause of diseases in farm animals: Current knowledge and future directions

Over the past 50 years, biomedical research has established a strong linkage between psychosocial stress and disease risk in humans, which has transformed the understanding of stress and the role it plays in human lives. This research has led to personalized medicine where a reduction in daily life stress is a main goal for many people with debilitating illnesses. This review describes the supporting evidence that social stress also plays a critical role in farm animal disease prevention, and may be a mediator by which common management practices can increase disease risk. There is evidence that social factors, including deprivation of social contact ('social isolation'), reducing space allowance ('crowding') and disturbing social order ('social instability') trigger physiological and behavioral indicators of stress in livestock. Less research exists, however, linking management practices that trigger social stress with higher disease risk. Suggestions are offered for future research opportunities, and practical, evidence-based recommendations are made for reducing the negative effects of social isolation, instability and crowding. The current evidence that social factors contribute to disease risk in farm animals is not as convincing as the human literature, but remains a promising and important area for future research.

Frontal Brain Activity and Behavioral Indicators of Affective States are Weakly Affected by Thermal Stimuli in Sheep Living in Different Housing Conditions

Many stimuli evoke short-term emotional reactions. These reactions may play an important role in assessing how a subject perceives a stimulus. Additionally, long-term mood may modulate the emotional reactions but it is still unclear in what way. The question seems to be important in terms of animal welfare, as a negative mood may taint emotional reactions. In the present study with sheep, we investigated the effects of thermal stimuli on emotional reactions and the potential modulating effect of mood induced by manipulations of the housing conditions. We assume that unpredictable, stimulus-poor conditions lead to a negative and predictable, stimulus-rich conditions to a positive mood state. The thermal stimuli were applied to the upper breast during warm ambient temperatures: hot (as presumably negative), intermediate, and cold (as presumably positive). We recorded cortical activity by functional near-infrared spectroscopy, restlessness behavior (e.g., locomotor activity, aversive behaviors), and ear postures as indicators of emotional reactions. The strongest hemodynamic reaction was found during a stimulus of intermediate valence independent of the animal's housing conditions, whereas locomotor activity, ear movements, and aversive behaviors were seen most in sheep from the unpredictable, stimulus-poor housing conditions, independent of stimulus valence. We conclude that, sheep perceived the thermal stimuli and differentiated between some of them. An adequate interpretation of the neuronal activity pattern remains difficult, though. The effects of housing conditions were small indicating that the induction of mood was only modestly efficacious. Therefore, a modulating effect of mood on the emotional reaction was not found.

Identification of QTLs for behavioral reactivity to social separation and humans in sheep using the OvineSNP50 BeadChip

Background

Current trends in sheep farming practices rely on animals with a greater level of behavioral autonomy than before, a phenotype that actively contributes to the sustainability of animal production. Social reactivity and reactivity to humans are relevant behavioral traits in sheep, known for their strong gregariousness and weak tolerance to handling, which have previously been reported with moderate to high heritabilities. To identify loci underlying such behaviors, we performed a genome study in Romane lambs.

Results

The experiment was carried out on 934 male and female lambs allocated into 9 half-sib families (average of 103 lambs per family) and reared outside. After weaning, all the lambs were individually exposed to 4 standardized behavioral tests combining social isolation, exposure to humans or handling, confinement and novelty (i.e. arena test, corridor test, isolation box test, shearing test). A broad range of behaviors including vocalizations, locomotion, vigilance and flight distance, as well as the cortisol response to handling, were collected. All lambs were genotyped using the Illumina OvineSNP50 BeadChip. QTL detection was performed by linkage, association and joint linkage and association analyses using the QTLmap software. Five main QTL regions were identified on sheep chromosomes (Ovis Aries Region, OAR) 12, 16, 19, 21 and 23 among many other QTLs with small to moderate effects. The QTLs on OAR12, 16 and 21 showed significant associations with social reactivity. The QTLs on OAR19 and 23 were found to be associated with reactivity to humans. No overlapping QTLs were identified for the different traits measured in the behavioral tests, supporting the hypothesis that different genetic factors influence social reactivity and tolerance to humans.

Conclusion

The results of this study using ovine SNP data suggest that in domestic sheep the behavioral responses to social separation and exposure to humans are under polygenic influence. The most relevant QTLs reported in the present study contain interesting candidate genes previously described to be associated with various emotional and social behaviors in mammals.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-778) contains supplementary material, which is available to authorized users.

Multidisciplinary approaches and assessment techniques to better understand and enhance zoo nonhuman animal welfare

Nonhuman animal welfare is a complex concept that encompasses an animal's biological functioning, emotional states, and opportunities to experience a natural life, including the performance of natural behaviors. Further, animal welfare can be viewed as quality of life from the perspective of the animal and thus must consider the animal's subjective experiences. Therefore, assessing and enhancing animal welfare should include multidisciplinary, scientific ventures that strive to create a complete picture of how animals' bodies and minds respond to both aversive and pleasant situations. Practical assessment of animal welfare should include outcome-based measures from the animal that provide information about the individual's welfare as well as resource-based measures that can help identify causes of or risk factors for poor welfare. Increasingly, scientists are examining the emotional states of animals as well as the impact of pain, pleasure, and consciousness on animal welfare. This article discusses approaches such as preference testing, instrumental learning, examination of space and resource use, and qualitative assessments of animal welfare that might be useful and practical for assessing and enhancing welfare in zoo settings.

Maternal influence on feeding site selection of male and female lambs

We conducted an experiment to determine whether early-life social learning of feeding site selection in lambs was sex-specific. Sixteen ewes and their new born lambs were used in a controlled experiment. Eight ewe-lamb pairs included a male lamb and the remaining eight a female lamb. All pairs were individually exposed to an experimental arena containing a safe and unsafe artificial feeding site (SFS, UFS) each consisting of nine bowls which contained either ground Bermuda grass hay (SFS) or ground alfalfa hay (UFS). The bowls in UFS were surrounded by bright orange traffic cones (visual cues). Half the ewes were trained with controlled electric shock to avoid UFS. Thus, pairs were randomly assigned to: (1) shock aversion training (SAT) to mothers of male lambs (MS); (2) SAT to mothers of female lambs (FS); (3) no aversion training (NAT, control) to mothers of male lambs (MC); and (4) NAT (control) to mothers of female lambs (FC). None of the lambs were subjected to SAT. During training, testing, extinction, and retraining ewe-lamb pairs were exposed to the arena together. Ewes were then removed from the experiment and two additional extinction phases were conducted with weaned lambs alone. Fear conditioning elicited UFS avoidance of both the trained ewes (means±s.e.m. % times observed in UFS during testing phase: FC=95.3±1.70; MC=94.4±4.87; FS=1.6±1.63; MS=0 ±0; P<0.01) and their naïve lambs (FC=83.8±6.07%; MC=76.6±6.56%; FS=30.4±7.90%; MS=33.9±9.23%; P<0.01). UFS avoidance in lambs occurred regardless of sex and tended to persist after weaning (% times observed in UFS during 1st post-weaning extinction phase: FC=92.6±4.50%; MC=89.8±6.09%; FS=45.1±10.57%; MS=43.5±10.42%; P=0.06). Fear conditioning in mothers appeared to alter sex-related differences in mother-infant behavioral synchrony by increasing and decreasing feeding synchrony of male and female lambs, respectively (FC: r=0.52, P<0.01; MC: r=-0.02, P=0.86; FS: r=0.14, P=0.26; MS: r=0.46, P<0.01). During the extinction phase mothers of ram lambs were observed feeding more often (FC=85.0±2.33%; MC=92.7±1.45%; FS=47.3±8.81%; MS=72±5.68%; P=0.02) and standing less often than ewes with daughters (FC=7.3±2.40%; MC=2.7±0.83%; FS=39.3±9.04%; MS=18.0±5.29%; P=0.06). This study suggests that social conditioning at an early age could be a viable tool to induce learning of feeding site avoidance in female and male lambs alike.

The valence of the long-lasting emotional experiences with various handlers modulates discrimination and generalization of individual humans in sheep

Between-farm variation in animal reactions to humans can reflect different management styles and behavioral tendencies among farmers. Animals are well known to discriminate among humans, but less clear is the key issue of whether they more or less easily generalize their experience from specific humans to others depending on management style. Here, we chose 2 contrasted management styles by known handlers: "gentle" management, that is, long-lasting exposure to positive human interactions (with limited negative interactions), and "aversive" management including long-lasting exposure to various negative human interactions (with only food delivery considered a positive interaction) and aversive events. Over a period of 19 wk, 15 female lambs were exposed to the gentle management treatment ("gently treated" group) and another 15 lambs ("aversively treated" group) were exposed to the aversive management treatment. To facilitate discrimination by animals, experimenters wore white clothes for aversive events and green clothes for farming handling (positive handling and feeding for the gently treated group and only feeding for the aversively treated group). Sheep perception of the human was assessed after the management period by submitting lambs from each group to 2 standardized tests: 1) the presence of a stationary human (familiar human in white vs. familiar human in green vs. unknown human) and 2) the presence of a moving human (familiar human in white vs. familiar human in green vs. unknown human). As expected, during the stationary human test, aversively treated lambs spent less time in the human zone (P<0.0001), showed greater latency to approach the human (P=0.05), and had fewer contacts with the human (P=0.05) than gently treated lambs. During the moving human test, aversively treated lambs also showed a greater escape distance from humans than gently treated lambs (P<0.0001). Aversively treated lambs showed the same fear responses towards familiar and unknown humans and tended to generalize their aversive experiences with one handler to all humans. In contrast, gently treated lambs seemed to discriminate familiar humans from unfamiliar humans. Different management styles could modulate farm generalization to humans in farm animals.

Development of affinity to the stockperson in lambs from two breeds

The interactions between genetic and environmental factors on the development of lamb affinity to humans was assessed on 48 animals from two breeds (Gentile di Puglia and Comisana) and two treatments (Gentled and Not Gentled) producing 4 groups (GPg, GPng, Cg, Cng, respectively). The Gentile di Puglia and Comisana gentled animals were subjected to a period of training consisting of gently handling each lamb for 5 min three times a day for the first week and then twice a week for three additional weeks. The gentling procedure included both tactile and visual/auditory interactions. At 30-32 days of age lambs were subjected to three arena tests conducted in a novel environment: i) isolation test (each animal was exposed to a novel environment, and isolated from tactile and visual contact with conspecifics for 5 min), ii) stationary human test (as previously but a human sitting in a corner of the pen), and iii) pen-mates' test (each animal was tested in the presence of 2 pen-mates whose behaviour was not recorded). During the 13 training sessions lambs exhibited an increasing number of contacts with the human and a decreasing number of bleats (P<0.001), although Gentile di Puglia lambs interacted more with the human (P<0.001) and tended to bleat less (P<0.10) than Comisana lambs. Lambs vocalised more and climbed more when tested in isolation as compared with lambs tested either with the human or with the pen-mates (P<0.01) and they vocalised more in the presence of the human than with the pen-mates (P<0.001). A higher number of contacts with the human stimulus was observed in gentled animals (P<0.05). However, differences between gentled and not gentled animals were only significant in Gentile di Puglia subjects (P<0.01). GPng lambs displayed the longest ambulatory activity during the isolation test (P<0.05) and exhibited more climbing attempts during the isolation test as compared with the human or the pen-mates' tests (P<0.001). A higher cortisol level was shown by GPng lambs in comparison with Cng subjects during the stationary human test (P<0.01), whereas no differences were detected between the two gentled groups. Gentling determined an improvement of the quality of human animal relationship in more reactive breeds such as Gentile di Puglia sheep.

Multiple exposures to familiar conspecific withdrawal is a novel robust stress paradigm in ewes

Paradigms used so far to study the effects of social isolation in sheep confound the effects of social isolation with those of other stressors (e.g. new environment) and showed contradictory effects after multiple social isolations. We propose here to characterize and examine the repeatable effects of social isolation induced by the familiar conspecific withdrawal (FCW). This latter test consists of socially isolating the ewe by the removal of group mates from the room test for 3 h. Behavioral and endocrine responses of adult ovariectomized-estradiol implanted ewes were compared 90 min before and 90 min after FCW, which was applied three times every fourteen days. We observed that each FCW induced significant increases in plasma cortisol level, in the number of vocalizations, foot pawing, circling attempts and a significant decrease in time spent lying down. An increase in plasma cortisol levels and decrease in duration of maintenance behaviors were significantly lower after the third FCW than after the first one. These differences could be explained by higher plasma cortisol levels and lower duration of maintenance behaviors before the third FCW than before the first FCW suggesting an anticipation of the social isolation period. These data indicate that social isolation is sufficient to induce distress with stable stressful responses after multiple exposures to familiar conspecific withdrawal.

Associations between open-field behaviour and stress-induced hyperthermia in two breeds of sheep

In sheep (Ovis aries) and other farm animals, routine husbandry procedures can cause negative emotions, such as fear, which are generally considered to reduce animal welfare. The open-field test (OFT) is the most widely used test to measure fearfulness in animals. The induction of psychological stress is often accompanied by an elevation of core body temperature, referred to as stress-induced hyperthermia (SIH) and both OFT and SIH were used in this study to measure fearfulness in sheep: the aim being to examine associations between behaviour in the OFT and the SIH response, using data from two breeds of sheep tested repeatedly over time. Twentyfour ewes from two breeds, Lacaune and Ripollesa, were tested for 10 min with all behaviours recorded throughout. Rectal temperature was measured immediately prior to the start of the test (T1) and 10 min after its completion (T2). SIH was measured as the difference between T2 and T1. Sheep were tested over three periods of three experimental days each. Ewes of both breeds showed consistent changes in behaviour in the OFT and a clear SIH response. Bleats and visits to the water bucket showed a clear pattern between rounds. Differences between T1 and T2 were found, T2 was higher than T1 suggesting that exposure to a novel arena caused SIH. Breed differences were found whereby T2 was 0.12°C higher in Ripollesa than Lacaune. These findings have implications for selection programmes, creating the possibility of selecting less fearful animals that will cope better with handling procedures that may induce fear. Further, they also demonstrate the importance of using both behavioural and physiological variables to evaluate fear.

Effect of perphenazine enanthate on open-field test behaviour and stress-induced hyperthermia in domestic sheep

The open-field test (OFT) and stress-induced hyperthermia (SIH) have been used to measure individual differences in fear. The present study has been designed as a pharmacological validation of OFT and SIH as indicators of fear in sheep using perphenazine enanthate (PPZ), a long-acting neuroleptic. Twenty four ewes of two breeds, Lacaune and Ripollesa, were tested in an arena measuring 5mx2.5m. Treatment group received one dose of 1.5mg/kg of PPZ and control group received sterile sesame oil. All animals were tested for 10min and behaviours were recorded. Rectal temperature was measured at the beginning (T1) and at the end (T2) of the test. SIH was defined as the difference between T2 and T1. Sheep were tested on days 1, 2, 3, 4, 7 and 9 after PPZ injection. Variables were analysed using a mixed model. PPZ decreased bleats on days 2, 3, 4 and the SIH response on days 2 and 3. Breed differences were observed. Treated animals showed positive correlations between SIH and bleats; squares entered; attempts to escape and negative correlation between SIH and visits to the food bucket. Our results suggest that behaviour and SIH on the OFT are useful measures of fear in sheep.

Temperament in preweanling horses: development of reactions to humans and novelty, and startle responses

The purpose of this study was to investigate the development and the stability across situations and over time of three temperament traits in young foals: propensity to react to humans, propensity to react to novelty, and propensity to react to suddenness. In a comparative study, we examined the reactions of animals in three independent groups (N = 27) tested at 3, 12, and 24 weeks of age, respectively. We observed that human avoidance and novel object approach behaviors are quasi inexistent in the group tested at 3 weeks, but are more and more present in the groups tested at subsequent ages. In a longitudinal study, we tested 48 foals successively at 3, 6, 12, and 24 weeks of age. Since reactions appear progressively with time, no stability over time or across situations was found. However, once a foal manifests a behavioral reaction at a given age, it will always reproduce this reaction subsequently.