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Acceptability of the food

In livestock production, pigs exposed to stressors during sensitive periods (weaning, peripartum) may depress their eating behaviour.  Improving the acceptability of the novel food by sensory functional ingredients might be a way to modulate the appetite,  food intake, and preferences, possibly counteracting neophobic responses or the development of food aversion during food transitions in farm animal, or human eating disorders related to medical treatment such as chemo- or radiotherapy, as well as  in the elderly.

Ethological methods and functional brain imaging techniques

The behavioural and neurobiological mechanisms underlying the hedonic modulation of food intake in juvenile pigs was studied through paradigms of conditioned food preferences and aversions, using behavioural conditioning and feed choice methods, and functional brain imaging approaches (thesis C. Clouard). The development of a pig model of conditioned food aversion using food flavours related to LiCl injection has been validated. Only a sweet and caloric reinforcement, such as saccharose (10%), induced a food preference conditioning in pigs.

Using brain imaging techniques, both exposure to food flavours with contrasted hedonic values and combined oral and duodenal sucrose sensing triggered differential activation in brain networks known in humans and rodents to be involved in the recognition and hedonic evaluation of sensorial stimuli, motivation, reward processes, and memory.
Significant similarities between brain responses in pigs and humans to the hedonic modulation of food intake were validated.

Increase knowledge of the process exacerbated food choices

Further studies are needed to investigate to what extent some factors of variation related to the animals (age, sex) or to the experimental paradigms may have influenced the expression of conditioned food preferences and aversions. These studies will allow a better understanding of the hedonic value of sensory additives in food and their impact on the development of aversions and/or preferences during food transitions in pigs. They also open the way to clinical applications , particularly to understand how exacerbated preferences or further addiction to sugar, are establishing in young individuals.

For further information

Clouard, C., Loison, F., Meunier-Salaün, M.-C., Val-Laillet, D. (2013). An attempt to condition flavour preference induced by oral and/or postoral administration of 16% sucrose in pigs. Physiology and Behavior, 124C, 107-115. (DOI)
Clouard, C. et al. 2012. Food preferences and aversions in human health and nutrition: How can pigs help the biomedical research? Animal 6, 118-136. (DOI)
Clouard, et al. 2012. Flavour preference acquired via a beverage-induced conditioning and its transposition to solid food: Sucrose but not maltodextrin or saccharin induced significant flavour preferences in pigs. Appl. Anim. Behav. Sci. 136, 26-36. (DOI)
Clouard, C. et al, 2012. Exposures to conditioned flavours with different hedonic values induce contrasted behavioural and brain responses in pigs. PLoS ONE 7, e37968. (DOI)

Contact

Marie-Christine Meunier-Salaün, UMR PEGASE, équipe SysPorc (Marie-Christine.Salaun[at]rennes.inra.fr)
David Val-Laillet, UR ADNC (david.val-laillet[at]rennes.inra.fr)