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Behavioural and neurobiological mechanisms underlying the establishment of food preferences and aversions in pigs: Applications in animal and human health and nutrition

Sweet (saccharose 10%) and caloric reinforcement is an efficient stimulus for food preference conditioning in pigs. Exposure to food flavours with contrasted hedonic values and combined oral and duodenal sucrose generated differential activation in brain networks known in human and rodents to be involved in the recognition and hedonic evaluation of sensorial stimulation, motivation, reward processes and memory.

3D Visualisation of a pig brain made on the SENAH medical imaging platform in Rennes. © INRA, RUELLE Chantal
Updated on 06/26/2014
Published on 12/18/2013

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 feeding choice methods, and functional brain imaging techniques (Thesis of C. Clouard). A pig model of conditioned food aversion using food flavours related to aversive effect (Licl injection) has been validated. Only sweet (saccharose 10%) and caloric reinforcement is an efficient stimulus for food preference conditioning in pigs. Exposure to food flavours with contrasted hedonic values and combined oral and duodenal sucrose generated differential activation in brain networks known in human and rodents to be involved in the recognition and hedonic evaluation of sensorial stimulation, motivation, reward processes and memory.

In livestock production, pigs exposed to stressors during sensitive periods (weaning, peripartum) may depress their feeding behaviour.  Improving the acceptability of the novel food by sensory functional ingredients would be a way to modulate the appetite and food intake and preferences and thus counteract neophobic responses or the development of food aversion during food transitions in farm animal, or in humans related to medical chemo or radiotherapy or in the hospitalized elderly.

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.

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

 

Publications/presentations: International Ethological Conference 2011, Congrès Société Française du Comportement Animal 2011, Journées de la Recherche Porcine 2012

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references

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.

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.

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.