Véronique Deiss

Measuring judgement bias and emotional reactivity in sheep following long-term exposure to unpredictable and aversive events

Animal welfare research is now starting to measure the cognitive component of affective states in an effort to improve welfare assessments of animals. Twenty-six Romane ewe lambs were trained to a spatial location task previously demonstrated to test for judgement bias in sheep. This required a go/no-go response according to the location of a bucket in a pen, with one location being positively reinforced (with a feed reward) and the other negatively reinforced (with a fan-forced blower). While training in the judgement bias arena continued, half of the sheep (n=13) were subjected to a chronic, intermittent treatment that consisted of stressful events common to production systems. After 3 weeks of treatment, all sheep were tested for biases in judgement by placing the bucket in ambiguous locations between the two learnt reference locations. The emotional reactivity, as characterised by behavioural and physiological responses, of all sheep to events that were unexpected, novel or sudden was then tested. A significant treatment × bucket location interaction was seen on day 3 with Stressed sheep approaching the bucket locations less than Control sheep (p=0.007). This may reflect a bias in judgement, however it is also possibly a treatment-induced difference in learning. Cardiac data did not indicate treatment differences, however the RMSSD of Control sheep in novel and unfamiliar situations was always higher than the Stressed animals. No meaningful treatment differences in emotional reactivity behaviours were evident. This paper provides further evidence that affective states exist and can be measured in animals.

Behavioural and physiological reactions of cattle in a commercial abattoir: relationships with organisational aspects of the abattoir and animal characteristics.

Behavioural, physiological and metabolic reactions of cattle to handling and slaughter procedures were evaluated in a commercial abattoir, from arrival until slaughter. Different genders or breeds were not subjected to the same procedures due to abattoir equipment or organisational aspects of the abattoir. Reactions to similar slaughter procedures varied according to animal characteristics and could have consequences for subsequent handling procedures. Factors that appeared to cause handling problems and vocalisation were excessive pressure during restraint, and distractions in the corridor such as noise, darkness, seeing people and activity. Post-mortem muscle metabolism depended on slaughter procedures. Following stunning or halal slaughter, some animals showed head rising movements despite the abolition of the corneal reflex, suggesting that head rising is not always indicative of consciousness. Overall, this study presents concrete data on how different types of cattle may react to slaughter procedures with a direct interest for the abattoir itself but also for scientific purposes.

Long-term exposure to unpredictable and uncontrollable aversive events alters fearfulness in sheep.

Numerous studies have investigated the emotional effects of various acute, potentially alarming events in animals, but little is known about how an accumulation of emotional experiences affects fearfulness. Fearfulness is a temperament trait that characterizes the propensity of an individual to be frightened by a variety of alarming events. The aim of this study was to investigate a putative alteration of fearfulness in sheep repeatedly exposed to various aversive events. Forty-eight 5-month-old female lambs were used. Over a period of 6 weeks, 24 of them (treated group) were exposed daily to various unpredictable and uncontrollable aversive events related to predatory cues, social context and negative handling that can occur under farming conditions. The other 24 lambs (control group) were housed in standard farming conditions (predictable food distribution and group handling). Fearfulness (behavioural and physiological responses) was assessed before and after the treatment period by subjecting the lambs to three standardized tests: individual exposure to suddenness and then to novelty in a test arena, and group exposure to a motionless human in the home pen. As biomarkers of stress, leukocyte counts, heart rate and cortisol concentrations were measured in the lambs in their home pens. Before the treatment, the emotional responses of the groups did not differ. After the treatment, treated lambs approached the human less often, had less contact with the novel object and vocalized more than controls in individual tests, suggesting that long-term exposure to unpredictable and uncontrollable aversive events increases subsequent fearfulness in sheep. In addition, treated lambs had lower leukocyte counts, heart rate and cortisol levels, pointing to a chronic stress state. These findings suggest that increased fearfulness may be used as a sign of chronic stress in farm animals.

Effects of feed deprivation on behavioral reactivity and physiological status in Holstein cattle.

The present study evaluated whether feed deprivation can increase reactivity to stressful events, such as those that can occur at slaughter. Therefore, effects of 30 h of feed deprivation on behavior, including reactions to psychological stressors, and physiological status in cattle were determined. Sixteen Holstein cows (Exp. 1) and 32 Holstein heifers (Exp. 2) were either fed (FE) or 30-h feed deprived (FD). Throughout the first day of feed deprivation and during evening feed distribution to control animals, FD heifers and cows were more active than controls (P < 0.05). In Exp. 1, during a feeding test, in response to a sudden air blast arising from the bucket from which the cow was feeding, FD cows showed a longer latency to return to feed (P = 0.0002), spent less time in the bucket air blast zone (P = 0.008) and less time motionless (P = 0.03), and tended to withdraw over a longer distance (P = 0.07) than FE cows. In Exp. 2, during a reactivity test, FD heifers spent more (P = 0.0001) time motionless in response to social isolation than FE heifers. In Exp. 2, one-half of the FE and FD heifers were subjected to an additional physical and psychological stressor just before the reactivity test by driving them for 5 min through a labyrinth. Within heifers subjected to the additional stressor, FD heifers were less accepting of being detained (P = 0.05) and stroked (P = 0.003) by a familiar stockperson in a corner of the test arena. Compared with FE animals, FD heifers and FD cows had greater plasma cortisol concentrations (P < 0.05). Feed-deprived cows also had reduced β-hydroxybutyrate concentrations (P = 0.02) compared with FE cows. Thus, in cattle, FD influenced some of the classical indicators of energy metabolism and exacerbated reactivity to sudden events. In addition, when additional stressors were applied, FD cattle were more reluctant to accept handling. Results indicate that a multifactorial origin of stressors during the slaughter period may synergistically increase psychological stress of cattle.

An assessment of the impact of rumenocentesis on pain and stress in cattle and the effect of local anaesthesia

Rumenocentesis is commonly used to collect rumen fluid to screen for acidosis. This study was designed to investigate whether rumenocentesis induced pain and stress and, if so, whether local anaesthesia could limit this. Twenty-four dairy cows were assigned to one of three treatments: (1) rumenocentesis with local anaesthesia (AR); (2) rumenocentesis without local anaesthesia (R); and (3) local anaesthesia only (A). Treatments were performed in a restraining cage. The cows were placed in the cage on three consecutive days and anaesthesia and/or rumenocentesis was performed on the second day. Blood samples for cortisol determination and heart rate were recorded from 0.25 h before treatment until 4h after. Behaviour was noted while the cows were caged. Feed intake and milk production were measured the week before treatment, on the day of treatment, and the day after. With all three treatments, cortisol concentrations and heart rate were increased while cows were in the cage. Cortisol, cardiac and behavioural responses were not significantly higher in the R and AR treatments than the A group. Cortisol concentrations and heart rate did not change between days. Feed intake and milk production were unaffected by the treatments. It was concluded that rumenocentesis does not appear more stressful than local anaesthesia or handling.

Consciousness, unconsciousness and death in the context of slaughter. Part II. Evaluation methods

This second review describes indicators of consciousness and unconsciousness that can be used in the abattoir. These indicators evaluate different aspects of cerebral functioning, but only indirectly. It is therefore necessary to monitor several indicators. Animals are considered unconscious if signs of consciousness are absent, and signs of unconsciousness are present. Given that the unconscious state may be reversible it is further necessary to monitor these indicators until the end of bleeding. The techniques used to diagnose brain death in humans cannot be used in the slaughterhouse. Under field conditions, at the end of bleeding, the absence of breathing and of brainstem reflexes and the adequacy of the exsanguination are verified. If these three aspects are confirmed, in the context of the slaughterhouse and at this stage of the slaughter process the loss of vital functions is irreversible and the animal can be considered dead.

Consciousness, unconsciousness and death in the context of slaughter. Part I. Neurobiological mechanisms underlying stunning and killing

This review describes the neurobiological mechanisms that are relevant for the stunning and killing process of animals in the abattoir. The mechanisms underlying the loss of consciousness depend on the technique used: mechanical, electrical or gas stunning. Direct exsanguination (without prior stun) causes also a loss of consciousness before inducing death. The underlying mechanisms may involve cerebral anoxia or ischemia, or the depolarisation, acidification and/or the destruction of brain neurons. These effects may be caused by shock waves, electrical fields, the reduction or arrest of the cerebral blood circulation, increased levels of CO2 or low levels of O2 in the inhaled air, or the mechanical destruction of neurons. The targeted brain structures are the reticular formation, the ascending reticular activating system or thalamus, or the cerebral hemispheres in a general manner. Some of the techniques, when properly used, induce an immediate loss of consciousness; other techniques a progressive loss of consciousness.

Hedonism as a predictor of attitudes of young French women towards meat

Iron-deficient young women who are at risk of anaemia should be advised to eat red meat, a good food source of iron. However, red meat is known to elicit negative attitudes among young women, which could lead to low meat consumption. Several factors can contribute to meat attitudes. We therefore hypothesised that a good predictor of attitudes towards meat could be a positive affective component, for example, the pleasure of eating meat. In our study, 77 women with a mean age of 30.5 were surveyed. They were first asked about four hedonism variables (overall, eating, red meat and white meat hedonism) and ethical and nutritional concerns. Secondly, they were asked to express their attitudes of like/dislike towards meat by way of meat pictures, odours and taste. Red meat hedonism was first highly correlated with a liking of raw red and white meat pictures (0.41< or =r< or =0.68), followed by a liking of cooked red and white meat pictures (0.27< or =r< or =0.62). To a lesser extent, red meat hedonism was correlated with a liking of meat odours (0.29< or =r< or =0.38) and beef taste (r=0.32). Finally, red meat hedonism was the best predictor for most of the likings for red and white meat images. Thus, red meat images were pleasant for people who already like meat and did not encourage meat consumption among low meat-eating women.

Origins of movements following stunning and during bleeding in cattle

At slaughter, after stunning, the absence of certain physical signs such as eye movements/reflexes or rhythmic breathing helps determine whether the loss of consciousness was actually achieved. Cattle frequently show movements of neck and/or legs during the post-stun period. We evaluated 1) the origins of these movements in stunned unconscious cattle and 2) relationships with presence of ocular signs or breathing and shot characteristics. In stunned unconscious cattle, movements appear to be reflex-like, generated in the brain stem and/or spinal cord. First, in stunned unconscious cattle, movements could continue until 3 min after the start of bleeding. Second, severing the spinal cord in stunned unconscious cattle did not influence amount of movements. Third, in reaction to the skin cut and sticking, some unconscious animals showed a nociceptive withdrawal reflex. In bulls, following longer stun-stick delays, this response was weaker. Shot placement, post-stun movements and initial bleeding efficiency seemed related but the underlying mechanisms remain to be elucidated.

Comprendre la manière dont l’animal perçoit et évalue son environnement pour réduire son stress en abattoir : exemple chez les bovins

L’abattage démarre dès la préparation de l’animal en élevage pour le départ à l’abattoir et s’achève avec la mort de l’animal. C’est une période complexe : au cours des différentes étapes de l’abattage, des sources de stress d’origine physique, émotionnelle, sociale et cognitive interviennent. Alors que celles d’origine physique sont bien connues, les autres le sont moins. Elles ont pourtant un impact significatif sur l’état de stress des bovins. En effet, les perturbations sociales, l’exposition à des événements nouveaux et/ou soudains, les manipulations par l’homme ainsi que l’environnement visuel, sonore et olfactif sont autant de facteurs potentiellement stressants qui s’ajoutent et interagissent avec les contraintes physiques. Un certain nombre de conseils pratiques relatifs aux équipements et à la gestion des bovins permettent de limiter ces sources de stress. Associés à des observations du comportement des animaux au cours des différentes procédures de la période d’abattage, ils peuvent permettre de réduire considérablement le stress des bovins.