Isabelle Veissier

Assessment of positive emotions in animals to improve their welfare

It is now widely accepted that good welfare is not simply the absence of negative experiences, but rather is primarily the presence of positive experiences such as pleasure. However scientific investigation of positive emotions has long been neglected. This paper addresses two main issues: first, it reviews the current state of scientific knowledge that supports the existence of positive affective states in animals and, second, it suggests possible applications of this knowledge that may enhance quality of life under animal management conditions. In the first part of the paper, recent advances in psychology and neuroscience are reviewed to provide pragmatic frameworks based on cognitive processes (such as positive anticipation, contrast and controllability) for further investigations of positive emotions in animals. Thereafter, the neurobiological bases of positive emotions are highlighted in order to identify behavioral and physiological expressions of positive experiences in animals. Monitoring both the autonomic nervous system (via heart rate and its variability) and the immune system could offer relevant tools to better assess emotional states in animals, complementary to classical adrenocortical measures. In the second part of the paper, useful strategies for enhancing positive experiences (such as physical, social and cognitive enrichment or putative genetic selection) are outlined. Then this paper emphasizes practical applications for assessing and promoting positive emotions that may help in providing animals with a better quality of life. Play, affiliative behaviors and some vocalizations appear to be the most promising convenient indicators for assessing positive experiences in laboratory and farm animals under commercial conditions.

Heart rate variability as a measure of autonomic regulation of cardiac activity for assessing stress and welfare in farm animals : A review

Measurement of heart rate variability (HRV) is a non-invasive technique that can be used to investigate the functioning of the autonomic nervous system, especially the balance between sympathetic and vagal activity. It has been proven to be very useful in humans for both research and clinical studies concerned with cardiovascular diseases, diabetic autonomic dysfunction, hypertension and psychiatric and psychological disorders. Over the past decade, HRV has been used increasingly in animal research to analyse changes in sympathovagal balance related to diseases, psychological and environmental stressors or individual characteristics such as temperament and coping strategies. This paper discusses current and past HRV research in farm animals. First, it describes how cardiac activity is regulated and the relationships between HRV, sympathovagal balance and stress and animal welfare. Then it proceeds to outline the types of equipment and methodological approaches that have been adapted and developed to measure inter-beats intervals (IBI) and estimate HRV in farm animals. Finally, it discusses experiments and conclusions derived from the measurement of HRV in pigs, cattle, horses, sheep, goats and poultry. Emphasis has been placed on deriving recommendations for future research investigating HRV, including approaches for measuring and analysing IBI data. Data from earlier research demonstrate that HRV is a promising approach for evaluating stress and emotional states in animals. It has the potential to contribute much to our understanding and assessment of the underlying neurophysiological processes of stress responses and different welfare states in farm animals.

Exploration of the hypothalamic–pituitary–adrenal function as a tool to evaluate animal welfare

Measuring HPA axis activity is the standard approach to the study of stress and welfare in farm animals. Although the reference technique is the use of blood plasma to measure glucocorticoid hormones (cortisol or corticosterone), several alternative methods such as the measurement of corticosteroids in saliva, urine or faeces have been developed to overcome the stress induced by blood sampling itself. In chronic stress situations, as is frequently the case in studies about farm animal welfare, hormonal secretions are usually unchanged but dynamic testing allows the demonstration of functional changes at several levels of the system, including the sensitization of the adrenal cortex to ACTH and the resistance of the axis to feedback inhibition by corticosteroids (dexamethasone suppression test). Beyond these procedural aspects, the main pitfall in the use of HPA axis activity is in the interpretation of experimental data. The large variability of the system has to be taken into consideration, since corticosteroid hormone secretion is usually pulsatile, follows diurnal and seasonal rhythms, is influenced by feed intake and environmental factors such as temperature and humidity, age and physiological state, just to cite the main sources of variation. The corresponding changes reflect the important role of glucocorticoid hormones in a number of basic physiological processes such as energy metabolism and central nervous system functioning. Furthermore, large differences have been found across species, breeds and individuals, which reflect the contribution of genetic factors and environmental influences, especially during development, in HPA axis functioning. Usually, these results will be integrated with data from behavioral observation, production and pathology records in a comprehensive approach of farm animal welfare.

Emotions in farm animals: a new approach to animal welfare in applied ethology

One of the major topics of applied ethology is the welfare of animals reared by humans. Welfare can be defined as a state of harmony between an individual and its environment. Any marked deviation from this state, if perceived by the individual, results in a welfare deficit due to negative emotional experiences. In humans, verbal language helps to assess emotional experiences. In animals, only behavioural and physiological measurements help to detect emotions. However, how to interpret these responses in terms of emotional experiences remains an open question. The information on the cognitive abilities of farm animals, which are available but scattered, could help the understanding of their emotions. We propose a behavioural approach based on cognitive psychology: emotions can be investigated in farm animals in terms of the individuals appraisal of the situation. This evaluative process depends on: (a) the intrinsic characteristics of the eliciting event (suddenness, novelty, pleasantness); (b) the degree of conflict of that event with the individuals needs or expectations; and (c) the individuals coping possibilities offered by the environment. The result of such an evaluation determines the negative versus positive emotions. We propose an analysis of the emotional repertoire of farm animals in terms of the relationship between the evaluative process of the event on the one hand and the behavioural and physiological responses on the other hand.

On the way to assess emotions in animals: Do lambs (Ovis aries) evaluate an event through its suddenness, novelty, or unpredictability?

Appraisal theories provide a framework that gives insight into emotions and could allow comparisons across species. According to these theories, events are first evaluated on their suddenness, novelty, and unpredictability. The authors examined the ability of lambs (Ovis aries) to evaluate an event according to these 3 criteria through 3 tests. The lambs responded to suddenness with a startle response coupled with an increase in heart rate and to novelty with an orientation response coupled with an increase of vagal activity. There was no clear evidence that lambs can detect the predictability of an event. Those results support the usefulness of appraisal theories to assess emotion in animals.

The Welfare Quality® project and beyond: Safeguarding farm animal well-being

Abstract Welfare Quality® was the largest ever European research project on animal welfare. Here, we briefly describe some major achievements of Welfare Quality® and identify future research priorities, potential strategies and organisational structures to build on the outcomes. Achievements include: definition of principles and criteria of good welfare; development of standardised, primarily animal-based measures for each welfare criterion and their integration in an overall assessment model. Since Welfare Quality® could not answer all the questions we recommend: 1. Continued development and refinement of the assessment systems and extension to new species. 2. The development of automatic measures of welfare to reduce the duration of the assessment while still retaining its holistic nature. 3. Exploration of potential implementation strategies across food chain actors. 4. Establishment of an independent body to manage and update the assessment and information systems, support their implementation and inform and engage stakeholders.

Aggregation of measures to produce an overall assessment of animal welfare. Part 1: a review of existing methods.

Several systems have been proposed for the overall assessment of animal welfare at the farm level for the purpose of advising farmers or assisting public decision-making. They are generally based on several measures compounded into a single evaluation, using different rules to assemble the information. Here we discuss the different methods used to aggregate welfare measures and their applicability to certification schemes involving welfare. Data obtained on a farm can be (i) analysed by an expert who draws an overall conclusion; (ii) compared with minimal requirements set for each measure; (iii) converted into ranks, which are then summed; or (iv) converted into values or scores compounded in a weighted sum (e.g. TGI35L) or using ad hoc rules. Existing methods used at present (at least when used exclusively) may be insufficiently sensitive or not routinely applicable, or may not reflect the multidimensional nature of welfare and the relative importance of various welfare measures. It is concluded that different methods may be used at different stages of the construction of an overall assessment of animal welfare, depending on the constraints imposed on the aggregation process.

Nonnutritive oral activities and stress responses of veal calves in relation to feeding and housing conditions

Abstract This study assessed the extent to which eating solid foods and social contacts influence nibbling objects and improve the welfare of veal calves. Animals were fed milk replacer only vs. supplemented with solid foods and were housed in individual stalls vs. together in pens. Time budget, reactions to handling in a weighing machine, growth, health (length of medical treatments) and abomasal lesions were assessed. In addition, chronic activation of the hypothalamo–pituitary–adrenocortical axis was evaluated after ACTH and CRF challenges, and that of the sympathetic nervous system, through activities of catecholamine-synthesising enzymes. The provision of solid foods reduced time spent nibbling objects and being inactive in proportion to and at the time of the increase in time spent eating and chewing. The calves housed together in pens had higher basal cortisol levels and they reacted to weighing. Health and physiological indices of chronic stress did not vary with feeding or housing conditions. It is concluded that nibbling in veal calves derives at least in part from a lack of development of feeding behaviour appropriate to ruminants. There was no clear evidence of poorer welfare due to feeding on milk replacer only or individual housing, but calves reared in groups seemed more stressed by handling than calves reared in individual stalls.

Weaning in calves: Its effects on social organization

Abstract Two experiments were undertaken in order to determine the effects of late weaning on the social behaviour of calves. Control heifers that were still suckled were compared to heifers that were weaned and kept either alone (Experiment 1) or with other familiar cows (Experiment 2) and to heifers whose dams had cloth on the udders to prevent suckling (Experiment 1). Spatial repartition and social encounters were recorded at pasture from dawn to dusk. Weaned heifers gathered more and engaged in more social encounters between them than controls. These alterations were more striking when the heifers were kept alone after weaning and less striking when only suckling was prevented. Moreover, preventing suckling did not alter dam-young relationships (Experiment 1). Nevertheless, when the dams were returned to their young after a total 3-week separation, their attachment to their young seemed to have declined, whereas that of the calves to their dams had not (Experiment 2). It is concluded that the calf remains attached to its dam even after weaning and that the absence of this preferential social partner makes the young animal strengthen its bonds with other partners.

Ontogeny of social awareness in domestic herbivores

Abstract It is now well established that domestic animals construct responses to their environment that depend on experience and on integration of several features of the environment, including social partners. This ability to be aware of the environment is not fully developed at birth but improves and varies through the animals life. This topic is discussed on the basis of social processes in sheep and cattle. Social relationships of an animal with its conspecifics develop with age; they do not merely depend on pre-programmed behaviours but rely at least in part on learning of characteristics of the partners. Soon after birth, a strong preferential bond establishes with the dam then to a lesser extent, the young associates to other members of the flock, especially other young. The attractiveness of the group varies later in life due to external events or to physiological state: the abrupt separation from the dam at artificial weaning strengthens bonds between peers, whereas around parturition, females are less disturbed by isolation from the group. More recently, the awareness of social partners has been described in non-social contexts: the animal modifies its responses to events according to the presence of partners, and also to their emotional state and behaviour. The effects of partners seem to depend on their relationship with the animal and also on the social motivation of that animal, which both vary during its life. We recommend study of the ontogeny of awareness using the model of social influences.