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

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When exposed to novel food during food transitions, growing pigs often elicit a neophobic response that is responsible for decreased food consumption. Flavour preference conditioning may represent an interesting way to reduce neophobia and improve food intake in growing pigs. The present series of experiments investigated the pig's conditioned preference for a flavoured beverage added with different carbohydrates and sweeteners and the possible transition of those beverage-induced preferences to flavoured solid food. In Experiment 1A, nine juvenile pigs were given three two-day conditioning sessions: they received a flavoured beverage added with 1.125% sucrose (F + S 1.125) and a second flavoured beverage with no additive (F−). In Experiment 1B, nine juvenile pigs were given six two-day conditioning sessions: they received a flavoured beverage added with 10% sucrose (F + S 10) and a second flavoured beverage with no additive (F−). In subsequent two-choice drinking tests, the pigs exhibited no clear-cut preference for F + S 1.125, whereas F + S 10 was preferred compared to F− ( P < 0.05) but only during the first subsequent two-choice drinking tests, suggesting that pigs developed a short-term preference for the flavour previously paired with 10% but not 1.125% sucrose. The Experiment 2 was conducted to assess the independent effects of visceral (caloric intake) and gustative (sweet taste) reinforcement in flavour preference conditioning. Nine juvenile pigs were subjected to four three-day conditioning sessions: they received flavoured beverages added with 2.25% maltodextrin (F + m, caloric intake), 0.37% saccharin (F + s, sweet taste), or no additive (F−). During further two-choice drinking tests, no clear-cut preference emerged, but the consumption of F + m was 107% and 35% higher than that of F− and F + s, respectively. Despite pigs exhibited some conditioned flavour preferences during two-choice drinking tests in Experiments 1B and 2, no clear-cut preference was observed during two-choice feeding tests with flavoured solid food. Overall, these findings highlight the importance of the combination and/or synergy between gustative and visceral reinforcements for conditioned flavour preference and suggest that a visceral reinforcement via maltodextrin might be sufficient to condition such a preference. Moreover, the absence of clear-cut preference during two-choice feeding test illustrates the difficulty to transpose a flavour preference acquired via a sweet beverage to solid food. Further studies are needed to investigate the failure of saccharin-conditioned preference in pigs.