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The flavour preferences of piglets, or how to combat food refusals during weaning

Food transition periods can be problematic for young animals. To facilitate the acceptance of new foods, INRA scientists have shown that it is possible to condition the eating behaviour of piglets towards a flavour.Associating a flavour with a sweet taste and calorie intake – gustatory and caloric reinforcement – can induce food preferences in animals. This positive effect obtained with beverages opens new perspectives for the formulation of feeds that could favour the well-being and growth of piglets.

Porcelets de race Bayeux. © WEBER Jean
Updated on 02/12/2013
Published on 10/04/2012

The introduction of new foods into the daily ration of animals often causes them to refuse to eat (neophobia). This situation is notably encountered among piglets during weaning. This refusal, which in piglets can lead to weight loss and a deterioration in health, can have significant economic consequences for livestock breeders, related to delayed animal growth and the possible emergence of diseases on farms.

During previous studies, it had been shown that the eating preferences and choices of animals result from learning processes that allow them to preferentially consume foods with beneficial effects on their development and/or pleasure, and to avoid potentially toxic substances. Animals build their food preferences by memorising the sensory characteristics of foods (flavour, odour, texture, appearance) and associating them with post-ingestive consequences (e.g. satiation and satiety, etc.). The animals thus develop a series of food preferences and aversions, also known as a food repertoire, which will allow them to adjust their eating responses to new foods throughout their life.

Based on this ability of animals to build up a repertoire of positive or negative food signals, the INRA researchers wanted to determine whether it was possible to induce flavour preferences in the piglet using a flavoured beverage, in order to favour the transition to new solid foods. To induce this food conditioning, the researchers compared several learning strategies using beverages that:

  • Associated flavours with a sweet taste using a sweetener, saccharine (gustatory reinforcement)
  • Associated flavours with a calorie intake using maltodextrin, a polysaccharide without a sweet taste (caloric reinforcement)
  • Associated flavours with a calorie and sugar intake using sucrose, a caloric polysaccharide with a sweet taste (energy and gustatory reinforcement).

The scientists showed that a strategy coupling gustatory and caloric reinforcements was the most effective in inducing flavour preferences in piglets. Caloric reinforcement alone seemed to be able to induce a preference, but these results were less clear. The pigs did not display any interest in saccharine, which suggests the poor palatability of this sweetener in pigs rather than the impossibility of mere gustatory reinforcement to induce food preferences.

The scientists also observed that it was difficult to transpose a preference acquired via a beverage to a food, because the texture, taste and odour specific to the solid food could disturb or modify the flavour perception learnt by the animal. Retro-olfaction (perception of odours and aromas when the food is in the mouth) is crucial to perceiving a complete sensory image of a food. Further studies are necessary to identify the best way to condition a preference for a flavour that could be used as a food additive to facilitate transitions.

Additional studies involving brain imaging are ongoing to observe the brain areas that are stimulated by gustatory and/or caloric reinforcements, or by exposure to a preferred flavour. This will help the team to understand the neural mechanisms that underlie food preferences in pigs, and in the future will facilitate evaluations of the efficacy of a food formulation by observing the animal's brain areas that are stimulated by the food.

This work was carried out in the context of Caroline Clouard's thesis project, jointly supervised by D. Val-Laillet (ADNC) and M.C. Meunier-Salaün (PEGASE) and funded by INRA and the Brittany Regional Council.

Scientific contact(s):

  • Marie-Christine Meunier-Salaün (+ 33 (0)2 23 48 50 57) UR1348 PEGASE Physiologie, Environnement, Génétique pour l’Animal et les Systèmes d’Elevage
  • David Val-Laillet (+33(0)2 23 48 50 72) UR1341 ADNC Alimentation & Adaptions Digestives, Nerveuses et Comportementales

Find out more

  • Clouard, C. ; Meunier-Salaün, M.C.; Val-Laillet, D. Food preferences and aversions in human health and nutrition: how can pigs help the biomedical research? Animal. 2012, 6 (1) : 118-136
  • Clouard, C.; Chataignier, M.; Meunier-Salaün, M.C.; Val-Laillet, D. 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 pig; Applied Animal Behaviour Science. 2012, 136 (1) : 26-36
  • Clouard, C.; Meunier-Salaün, M.C.; Val-Laillet, D. The effects of sensory functional ingredients on food preferences, intake and weight gain in juvenile pigs. Applied Animal Behaviour Science. 2012, xxx (xxx) : Sous presse
  • Clouard, C; Jouhanneau, M.; Meunier-Salaün, M.C.; Malbert, C.H.; Val-Laillet, D. Exposures to conditioned flavours with different hedonic values induce contrasted behavioural and brain responses in pigs. PLoS ONE (accepted with modifications).