Gestational programming of olfactory-based behaviors by odor positive reinforcement – HAPPYSMELLING

In captive and production animals, housing conditions are often impoverished and monotonous, they restrict the expression of natural behaviors, impairing various indicators of welfare and markers of health and increasing public concern for animal welfare. Environmental enrichments have been proposed as strategies to complexify and dynamize environment, so that animals could develop improved repertoires of natural behavior. Odors have been recognized as good and easy-to-implement candidates for environmental positive enrichments to sustain behaviors and welfare, but their use is still largely overlooked. Yet, odors could benefit to both captive and farm animals, improving well-being, food intake and cognitive performances in adulthood. However, controversial and/or non-lasting effects are observed when these odors are associated with the maternal environment. This suggests that the robustness of behavioral effects may rely on the gestational context in which odor is learned, which has been poorly studied in positive contexts, mostly to modulate food preferences, but never evaluated for other important behavioral traits, such as the ingestive or the socio-emotional behavior, both factors that obviously participate to a positive welfare assessment. Finally, the long-term consequences of a maternal odor exposure on brain development and functioning, investigating the role of epigenetics as an intergenerational inheritance mechanism for transmission of innate odor-based behaviors, remain to be deciphered. The HAPPYSMELLING project examines the impact of a positive reinforcement associated to a gestational odor exposure on the programming of offspring’s eating and socio-emotional behaviors in two important periods of stress, namely birth and weaning. The project is conducted in parallel on two complementary animal models, mice and pigs, two altricial species with perinatal brain maturation, favoring complementary scientific questioning and methodologies, thus offering obvious cross benefits to this challenge. Indeed, in mice, the project combines behavioral investigations on food intake and social interactions with molecular analyses on structures related to odor perception to identify new regulatory genes and pathways supporting neurodevelopmental plasticity in a reinforced context, with a focus on DNA methylation as an important epigenetic contributor to behavioral disturbances. In parallel, in a translational perspective, the feasibility of a prenatal odor learning is conducted in pig, a species often raised in impoverished environment, where odor exposure could act on stress and food intake, thus providing new and easy-to-implement strategies to improve welfare in conventional farming conditions. As the welfare state of a sentient animal is a very complex affair and cannot be embraced by any single scientific discipline, this multidisciplinary project will integrate animal behavior and welfare with ethology, neurochemistry, epigenetics and physiology approaches.