From the pig's olfactory capacities to environmental enrichment

The aromatic substances contained in the foods and beverages of the mother's diet can reach the foetus via the amniotic fluid or placental bloodstream. Foetuses are thus able to perceive, memorize and associate these chemosensory signals with the mother's emotional states, assigning them a positive or negative valence. In pigs, exposure to an odour during foetal life will influence olfactory preferences for the same stimulus after birth. It also promotes food intake and growth, and reduces deleterious social behaviors during odor recall at weaning. Associating a gestational odour to a positive reinforcement for the mother could thus optimize the benefits observed on the offspring, by reducing weaning stress and, more generally, enhancing long-term animal welfare in conventional farms. Conventional husbandry systems are often characterized by poor and monotonous environments, which offer little sensory stimulation to the animals. This leads to boredom and frustration, with deleterious consequences for the well-being of the animals and their offspring .

Development of an odor-based prenatal enrichment strategy

Currently, little is known on the impact of positive prenatal olfactory learning on the offspring's socio-emotional and cognitive responses to odour recall, and on the neurobiological mechanisms underlying the hedonic processing of this learned odour. Therefore, the aim of this thesis project is to generate knowledge on the effectiveness of prenatal olfactory enrichment in improving the welfare of sows and their piglets, and to identify the underlying brain mechanisms.
To achieve this, we will use two animal experimental set-ups to expose pregnant sows to an odour in a positive context, and to evaluate the effects of recall of this odour on the behavioural and cerebral responses of their offspring. The first experimental set-up will consist in pairing the ingestion of the odour to a positive environment by providing sows with regular access to a "recreation room" featuring a variety of enrichments, such as areas with peat and straw beddings to forage in, brushes, odorized ropes and jute bags to chew on, music broadcasting, aerial diffusion of the odour, sweet odorised rewards. The second system will consist in exposing sows to the odour directly in their living environment by offering them sweet odorized rewards daily with positive contacts with the experimenters. The effects of the positive prenatal olfactory learning on the piglets will then be assessed by submitting piglets to a variety of behavioural tests and measurements, and to functional brain imaging (fMRI).

Emmanuelle Briard is working on this thesis subject since December 2023 for 3 years within the Welfare team of the Pegase research unit. She is supervised by Céline Tallet and Caroline Clouard.

Contact

Emmanuelle Briard (doctorante) : emmanuelle.briard[at]inrae.fr
Céline Tallet (Directrice de thèse) : céline.tallet[at]inrae.fr
Caroline Clouard (Co-directrice de thèse) : caroline.clouard[at]inrae.fr