To date, most studies on animal emotions have focused on the assessment of negative emotional states, and there is a lack of approaches to characterising positive emotional states. The aim of this ...investigation was to measure differences in ear and tail postures in sheep exposed to situations likely to induce states of negative, intermediate and positive emotional valence.
Nineteen female sheep were observed in emotion-eliciting situations in two experiments. In the home-pen experiment, ear and tail postures were observed during separation from group members (negative situation), during rumination (intermediate), and while feeding on fresh hay (positive situation). In the fodder experiment, individual sheep were conditioned to anticipate the delivery of standard feed. Once familiar with this experimental condition, they were offered either the standard feed (control treatment), unpalatable wooden pellets (negative treatment), or energetically enriched feed mixed with preferred feed items (positive treatment). Ear and tail postures of sheep were recorded during the final 6
min preceding feed delivery (anticipation phase) and for 6
min during feed delivery (feeding phase). Data were analysed using linear mixed-effect models.
In the home-pen experiment, sheep separated from group members showed a high number of ear-posture changes and a high proportion of forward ears compared to hay feeding, during which ears were mainly passive. In the fodder experiment, the total number of ear-posture changes was generally high during the anticipation phases, slightly lower during delivery of the wooden pellets, and clearly reduced during the delivery of standard and enriched feed. A higher proportion of passive ear postures occurred when standard feed and enriched feed were offered compared to the delivery of wooden pellets. The proportion of asymmetric and axial ear postures was influenced by the sequence of testing of the different feeding treatments, with a higher proportion of asymmetric and a lower proportion of axial ear postures during the first exposure to either the wooden pellets or the enriched feed. A high proportion of the sheep's tails being raised was only observed during separation from group members.
In both experiments, frequent ear-posture changes were most clearly associated with situations inducing negative states, and a high proportion of passive ear postures with situations likely to induce positive emotional states. Unfamiliarity influenced emotional reactions towards a more negative appraisal. A raised tail only appears to occur in specific situations, and was not useful for distinguishing emotional valence. Apart from the need for further validation, observations of ear-posture changes seem to be a promising approach for assessing emotional reactions in sheep.
In a semi-natural environment, a lot of the daily activity of pigs is spent in exploratory and foraging behaviour. Providing enrichment material attractive to the pigs both over the short and long ...term is therefore important in intensive housing systems. This study aimed to investigate the effect of four types of point-source enrichment materials and four types of litter on the behaviour of finishing pigs. In experiment 1, pigs were offered cut straw or cut straw enriched with maize kernels as litter on the lying area, as well as a cylindrical dispenser filled with a compressed straw block or a straw rack filled with cut straw. In experiment 2, chopped straw or chopped Miscanthus giganteus was provided as litter on the lying area, along with a straw-pellet dispenser or bark compost in a trough. In both experiments, 96 finishing pigs with undocked tails were housed in groups of six pigs in pens with partly-slatted floors. Half of the groups were fed restrictively, the other half ad libitum. Every three weeks, the enrichment materials were replaced. Exploratory behaviour directed towards the enrichment material, the pen equipment and pen mates was videorecorded and analysed by means of one-minute focal-scan sampling on the second and eighteenth day after provision of a new enrichment material. Data were analysed using linear mixed-effect models.
In both experiments, the frequency with which the enrichment material was explored was influenced by the interaction of type of material and day (p<0.001). On the second day after provision of enrichment, the favoured material was cut straw enriched with maize kernels in experiment 1, and the straw-pellet dispenser in experiment 2. On day 18, straw as litter with or without maize, the straw rack, chopped straw, chopped Miscanthus giganteus and the pellet dispenser were used with a similar, and still relatively high, frequency. The least-explored materials were the straw block and bark compost. In both experiments, pigs fed ad libitum explored the materials less than half as frequently as those fed restrictively (p<0.001). Manipulation of the pen showed a pattern inverse to that of manipulation of the material, but a similar pattern with respect to feeding regime. Materials had no discernible influence on the manipulation of pen mates. In conclusion, our results indicate that both the point-source enrichment and the litter materials provided constituted adequate enrichment for small groups of finishing pigs.
Confined goats spend a substantial part of the day feeding. A poorly designed feeding place increases the risk of feeding in nonphysiological body postures, and even injury. Scientifically validated ...information on suitable dimensions of feeding places for loose-housed goats is almost absent from the literature. The aim of the present study was, therefore, to determine feeding place dimensions that would allow goats to feed in a species-appropriate, relaxed body posture. A total of 27 goats with a height at the withers of 62 to 80 cm were included in the study. Goats were tested individually in an experimental feeding stall that allowed the height difference between the feed table, the standing area of the forelegs, and a feeding area step (difference in height between forelegs and hind legs) to be varied. The goats accessed the feed table via a palisade feeding barrier. The feed table was equipped with recesses at varying distances to the feeding barrier (5–55 cm in 5-cm steps) at angles of 30°, 60°, 90°, 120°, or 150° (feeding angle), which were filled with the goats' preferred food. In 18 trials, balanced for order across animals, each animal underwent all possible combinations of feeding area step (3 levels: 0, 10, and 20 cm) and of difference in height between feed table and standing area of forelegs (6 levels: 0, 5, 10, 15, 20, and 25 cm). The minimum and maximum reach at which the animals could reach feed on the table with a relaxed body posture was determined for each combination. Statistical analysis was performed using mixed-effects models. The animals were able to feed with a relaxed posture when the feed table was at least 10 cm higher than the standing height of the goats' forelegs. Larger goats achieved smaller minimum reaches and minimum reach increased if the goats' head and neck were angled. Maximum reach increased with increasing height at withers and height of the feed table. The presence of a feeding area step had no influence on minimum and maximum reach. Based on these results, the goats' feeding place can be designed to ensure that the animals are able to reach all of the feed in the manger or on the feed table with a relaxed posture, thus avoiding injuries and nonphysiological stress on joints and hooves. A feeding area step up to a maximum of 20 cm need not be taken into account in terms of feeding reach. However, the feed table must be raised at least 10 cm above the standing area to allow the goats to feed in a species-appropriate, relaxed posture.
The behaviour shown by an animal at any one time is the consolidated output of its behavioural control mechanism. Moreover, what animals “want” is viewed as (the most) important component for ...individual welfare. Accordingly, studying the motivation of animals helps understanding basic mechanisms and welfare related needs. However, studying wants of animals is notoriously difficult and many previous studies on the preferences of animals have been restricted in the sense that only two choice options were presented in an artificial test environment. Here, an extended approach, the “Small World” is presented, in which the choices of animals between eight ecologically relevant resources can be observed in a long‐term test to reach conclusions with respect to everyday moment‐to‐moment decisions. In this sense, the system offers a quasi‐natural environment. The approach was tested in three experiments with observations of individual female rats, small groups of female rats (Long Evans, Rattus norvegicus) and small groups of female chickens (Lohmann Brown, Gallus gallus domesticus). The animals oriented themselves quickly in the system and it was possible to collect multifaceted data on the use of the resources. These data included the faecal and urinary markings in the Small World cages, the daily frequency and duration of visits to these cages, the sequential analyses of the choices for and decisions among the resources, and the synchrony of the animals in the groups. Given the richness of these data and the lack of a stress response in the tested animals, the use of the Small World approach seems to be highly promising as an extension to previously used procedures. To further improve the approach and more directly reflect the subjective value of the different resources from the animals' point of view, the distances between the resources in a quasi‐natural landscape shall be manipulated in future studies.
In three pilot studies, rats and hens were studied in a Small World system. This approach allows the investigation of everyday moment‐to‐moment decisions under experimentally manipulable but ecologically meaningful conditions. These decisions are relevant for basic understanding proximate behavioural control mechanisms and behavioural needs in relation to questions of animal welfare.
•Sheep were confronted repeatedly with stimuli thought to elicit emotional reactions.•Activity, ear movements and postures, and frontal cortical activation were observed.•There was little systematic ...change with presumed valence of the stimuli.•Within- compared to between-sheep variability was much larger.•Valence and personality seemed to have been of little importance in this data set.
There is an increasing interest in affective states in applied animal behaviour science, because these states are thought to reflect welfare from the perspective of the animals. Also, it can be expected that individuals differ in how they consistently react to emotional challenges. Recently, we conducted three experiments in which the same sheep were repeatedly confronted with either physical, social or thermal stimuli that presumably varied in their valence. These sheep had been housed in either unpredictable, stimulus-poor or predictable, stimulus-rich housing conditions in order to manipulate their long-term mood. When the sheep were exposed to the stimuli, we measured general activity, ear movements, ear postures and frontal cortical haemodynamic changes as indicator variables for their emotional reaction. In the meta-analysis presented here, we searched for effects of the presumed valence and mood state on the indicator variables. Furthermore, we investigated the unexplained between- versus within-subject variability as an indicator of personality. Deoxy- HHb and oxy-haemoglobin concentrations O2Hb as well as general activity showed weak linear relationships with presumed valence. Sheep from the unpredictable, stimulus-poor housing conditions were generally more active and showed more ear movements, higher absolute HHb, more transverse ears and less left-forward ears than sheep from the predictable, stimulus-rich housing conditions. However, these differences were small. The ratio of between- to within-individual variability was very low indicating little consistency in individual reactions. In conclusion, we found only weak evidence that presumed valence had a consistent effect on the indicator variables for emotional reactions in a given sheep, and these reactions were not modulated by presumed mood. Also, there was little indication that the sheep reacted in a way reflecting an individualised personality.
Musculoskeletal disorders have been a main concern in milkers for many years. To improve posture, a formula was developed in a previous study to calculate ergonomically optimal working heights for ...various milking parlor types. However, the working height recommendations based on the formula for the herringbone 30° parlor were broad. To clarify the recommendations for the optimal working height, we investigated the effect of working height on upper limb and shoulder muscle contraction intensities. We evaluated 60 milking cluster attachment procedures in a herringbone 30° milking parlor in 7 men and 9 women. Specifically, we examined the effect of working height on muscle contraction intensity of 4 arm and shoulder muscles bilaterally (flexor carpi ulnaris, biceps brachii, deltoideus anterior, and upper trapezius) by using surface electromyography. The working heights (low, medium, and high), which reflect the ratio of the subject's height to the height of the udder base, were used in the milking health formula to determine and fit individual depth of pits. Data were evaluated for each muscle and arm side in the functions holding and attaching. Statistical analysis was performed using linear mixed effects models, where muscle contraction intensity served as a target variable, whereas working height coefficient, sex, subject height, and repetition were treated as fixed effects, and repetition group nested in working height nested in subject was considered a random effect. Contraction intensities decreased with decreasing working height for the deltoideus anterior and upper trapezius, but not for the flexor carpi ulnaris or the biceps brachii muscles in both holding and attaching arm functions. We found that milking at a lower working height reduced muscle contraction intensities of the shoulder muscles. Women showed higher contraction intensities than men, whereas subject height had no effect. The study demonstrated that a lower working height decreased muscular load during milking. These lower working heights should be used within the recommendations made by the milking health formula for the herringbone 30°. Working heights could be adjusted effectively for milkers of varying body height. Future studies should therefore use the milking health formula as a tool to objectively compare and improve the accuracy of the working height coefficients.
The affective state of an animal, which is thought to reflect its welfare, consists of both short-term emotional reactions and long-term general mood. Because this state is generated and processed by ...the brain, we used non-invasive measurement of such brain activity as a novel indicator variable and investigated the interplay of mood and short-term emotional reactions in animals. We developed a wireless sensor for functional near-infrared spectroscopy (fNIRS), which assesses cortical perfusion changes, and consequently neuronal activity. Mood differences were induced by barren and enriched housing in a total of nine sheep and we observed their brain reaction in response to the positive situation of being groomed. We detected a decrease in cerebral oxyhaemoglobin concentration (O2Hb) which persisted during grooming. The localisation of the decrease in the brain did not depend on the site where the stimulus was applied. Also, the intensity of the response did not depend on the intensity of the grooming stimulus and a sham stimulus did not evoke an O2Hb response as seen with a grooming stimulus. Thus, we conclude that the observed haemodynamic brain response was unlikely to reflect pure somato-sensory information. We then found that the amplitude of the O2Hb response was larger if sheep were in a supposedly more negative mood. This contradicts the common assumption that negative mood generally taints reactions to emotional stimuli. Our results also demonstrate the potential of fNIRS for assessing affective states in freely moving animals.
► This is the first study measuring affective brain states in unrestrained animals. ► Wireless functional near-infrared spectroscopy (fNIRS) assessed this brain activity. ► A novel in-vivo fNIRS device measured brain responses in freely moving sheep. ► Responses to a pleasurable grooming stimulus depended on the sheep's mood.
Dairy heifers are confronted with a number of changes in their environment before their first parturition. In this study, we examined the influence of an early exposure to a calving pen 4 weeks ...prepartum, combined with increased human–animal contact, on behavior around calving and avoidance distance of heifers. Data were collected on 65 Brown Swiss heifers on five Swiss dairy farms. On each farm heifers were randomly assigned to two treatment groups. Thirty-four treated heifers were singly housed for 24h in the calving pen 4 weeks before expected calving, a procedure that also involved handling by a human. Heifers of the control group (n=31) were housed for the first time in the calving pen on the days before and during parturition. Lying behavior was recorded using data loggers, and a human avoidance test involving a familiar and an unfamiliar person was conducted 4 weeks prepartum and 1 week postpartum. Additionally, interventions during parturition were logged. Neither the proportion of time spent lying observed for either 48 or 12h around birth nor the number of lying bouts observed for 48 around birth differed significantly between treated and control heifers (all P>0.20). In the period of 6h before to 6h after calving, the number of lying bouts decreased with number of days that heifers had spent in the calving pen before parturition for the treated heifers and increased for the control heifers (interaction P=0.019). The avoidance distance was higher for the unfamiliar than for the familiar person (P<0.001), tended to decrease from before to after calving (P=0.07), and did not differ between treated and control heifers (P=0.14). There was no significant difference in the risk of an intervention between treated and control heifers (P=0.24). In conclusion, these results do not provide evidence that an early exposure of dairy heifers to the calving pen had a positive effect on their lying behavior around parturition and avoidance distance. However, additional time in the calving pen pre-partum seemed to have a calming effect as reflected by the number of lying bouts in the treated but not the control heifers.
•Heifers were exposed to the calving pen and human handling prior to calving.•Lying behavior at calving did not differ between exposed and control heifers.•Avoidance distances towards humans did not differ between the two groups of heifers.•The risk for an intervention during parturition was not lower for exposed heifers.•Early exposure to the calving pen did not have effects on behavior at calving.
Animal welfare concerns have raised an interest in animal affective states. These states also play an important role in the proximate control of behaviour. Due to their potential to modulate ...short-term emotional reactions, one specific focus is on long-term affective states, that is, mood. These states can be assessed by using non-verbal cognitive judgement bias paradigms. Here, we conducted a spatial variant of such a test on 24 focal animals that were kept under either unpredictable, stimulus-poor or predictable, stimulus-rich housing conditions to induce differential mood states. Based on functional near-infrared spectroscopy, we measured haemodynamic frontal brain reactions during 10s in which the sheep could observe the configuration of the cognitive judgement bias trial before indicating their assessment based on the go/no-go reaction. We used (generalised) mixed-effects models to evaluate the data. Sheep from the unpredictable, stimulus-poor housing conditions took longer and were less likely to reach the learning criterion and reacted slightly more optimistically in the cognitive judgement bias test than sheep from the predictable, stimulus-rich housing conditions. A frontal cortical increase in deoxy-haemoglobin HHb and a decrease in oxy-haemoglobin O2Hb were observed during the visual assessment of the test situation by the sheep, indicating a frontal cortical brain deactivation. This deactivation was more pronounced with the negativity of the test situation, which was reflected by the provenance of the sheep from the unpredictable, stimulus-poor housing conditions, the proximity of the cue to the negatively reinforced cue location, or the absence of a go reaction in the trial. It seems that (1) sheep from the unpredictable, stimulus-poor in comparison to sheep from the predictable, stimulus-rich housing conditions dealt less easily with the test conditions rich in stimuli, that (2) long-term housing conditions seemingly did not influence mood—which may be related to the difficulty of tracking a constant long-term state in the brain—and that (3) visual assessment of an emotional stimulus leads to frontal brain deactivation in sheep, specifically if that stimulus is negative.
•Sheep discriminated video sequences of social interactions differing in valence.•Highest attentiveness was detected with videos of agonistic interactions.•fNIRS measurements showed highest cortical ...deactivation when sheep watched agonistics.•Housing conditions influenced the reaction of the animals towards stimulus valence.•Frontal cortical activity may depend on the perceptual channel used by the sheep.
Mood, as a long-term affective state, is thought to modulate short-term emotional reactions in animals, but the details of this interplay have hardly been investigated experimentally. Apart from a basic interest in this affective system, mood is likely to have an important impact on animal welfare, as bad mood may taint all emotional experience. In the present study about mood – emotion interaction, 29 sheep were kept under predictable, stimulus-rich or unpredictable, stimulus-poor housing conditions, to induce different mood states. In an experiment, the animals were confronted with video sequences of social interactions of conspecifics showing agonistic interactions, ruminating or tolerantly co-feeding as stimuli of different valences. Emotional reactions were assessed by measuring frontal brain activity using functional near-infrared spectroscopy and by recording behavioral reactions. Attentiveness of the sheep decreased from videos showing agonistic interactions to ruminating sheep to those displaying co-feeding sheep. Seeing agonistic interactions was also associated with a deactivation of the frontal cortex, specifically in animals living under predictable, stimulus-rich housing conditions. These sheep generally showed less attentiveness and locomotor activity and they had their ears in a forward position less often and in a backward position more often than the sheep from the unpredictable, stimulus-poor conditions. Housing conditions influenced how the sheep behaved, which can either be thought to be mediated by mood or by the animals’ previous experience with stimulus-richness in their housing conditions. Frontal cortical activity may not depend on valence only, but also on the perceptual channel through which the stimuli were perceived.
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