Modifications de la sensibilité émotionnelle et des capacités cognitives et sociales induites par le développement d'états affectifs durables chez les animaux d'élevage – EmoFarm

Farm animal welfare is one of the present societal concerns throughout the livestock production chain. Farm animal welfare concern results from the acceptance that animals are sentient beings, which means that they are capable to experience emotions and longer emotional states. In laboratory animals, it is well known that negative emotions are able to transiently alter cognitive processes such as perception, attention and memory, which can in turn change emotional states. However, while recent studies have started in farm animals to elucidate emotional reactions to various acute events, little is known of the persistent emotional changes occurring after repeated exposure to stressors. Moreover, despite a growing number attempts to enrich living conditions in livestock, the behavioural processes that underlie the quality of life need still to be elucidated. Therefore, using a conceptual framework originally developed in human psychology, EmoFarm project aims to study in farm animals: i) the effects of repeated exposure to stressors before their puberty on their subsequent emotional, cognitive and social abilities, and the consequences for their welfare, and ii) the effect of supposedly positive events on positive emotions in order to improve animal welfare. The project is running along 3 years. It will be carried out on sheep as a model of farm animals, and to a lesser extent on two genetic divergent lines of quail selected on their emotional sensitivity (i.e. high vs. low reactive). A first stage aims to study the effects of repeated stress on emotional state and cognitive ability. Repeated and unpredictable exposures to aversive events would induce a depressive state due to altered emotional reactivity, learning deficits and a negative perception of ambiguous events. Lambs will be exposed to repeated unpredictable aversive events for six weeks. After the end of stress treatment the animals will be tested with a battery of behavioural tests to assess their emotional reactivity and cognitive performances. The same procedure will be engaged on the quail lines to determine the influences of the emotional sensitivity on the development of a chronic stress. A pharmacological approach will be also carried out on sheep to distinguish between the emotional and the cognitive influences on behavioural reactions measured in tests. Finally a neurobiological approach will evaluate the functional changes in some subcortical structures (PVN, amygdala and hippocampus) following the chronic stress. The model of chronic stress will be then defined to be used in next two stages. A second stage aims to investigate the effects of emotional and cognitive disturbances induced by chronic stress on the social skills of animals, and more particularly on their relationships with flock-mates, sexual partners, offspring and humans. The approach will be conducted on the two animal models. The stress-induced effects on social behaviours should be more pronounced in quail selected for a high emotional reactivity. A third stage of EmoFarm will investigate whether the behavioural alterations of a chronic stress during ontogenesis may be alleviated by a chronic pharmacological antidepressant treatment or by repetitive positive emotional experiences. Tricyclic imipramine will be daily administered in lambs subjected or not to chronic stress in order to define the alleviating effects. Then, a behavioural strategy to alleviate stress-induced alterations will be tested on the two animal models. Referring to our conceptual framework, positive emotional experiences should be amplified by offering the possibility to the animals to predict rewards' venue (i.e. positive anticipation). Food delivery, access to a clean litter and introducing familiar play companions will be used as main rewards. The expected alleviation of the stress-induced alteration on the emotional and cognitive abilities should be more pronounced in animals trained with positive expectations (i.e. cognitive enrichment). EmoFarm is thus an integrative and multidisciplinary approach (ethology, neurophysiology, psychopharmacology and neurobiology) to study the emotional processes underlying welfare in farm animals. Results should help to understand how persistent maladaptive behaviours are developed after a long period of stress. In addition to the analytical approach, expected systematic emotional and/or cognitive changes induced by stress could be useful indicators to identify reduced welfare in farm animals. Likewise, if we found that a cognitive enrichment in the housing conditions alleviates stress-induced alterations, such approach could be promoted to improve animal management in livestock.