Devaluation of low-quality food during early experience by sheep

Abstract

A ruminant's early experience with low-quality food (LQF) is expected to increase its acceptance and preference in adulthood. Contrarily, we found that experienced sheep (ES) exposed to mature oat hay early in life ate less of this LQF than inexperienced sheep (IS). A possibility is that ES might have devaluated the LQF through continuous comparisons against high-quality food (HQF) supplements (sunflower meal and ground corn) that were simultaneously available during early experience. In this study, we tested the devaluation hypothesis with a successive negative contrast (SNC) procedure. In a consummatory SNC procedure, 'shift' subjects are unexpectedly changed from HQF to LQF, and their consumption is then compared against the consumption of 'unshift' subjects that receive LQF all throughout the SNC procedure. The magnitude of the difference in consumption between preshift and postshift is regarded as a measure of the degree to which both foods (HQF and LQF) are perceived to differ hedonically. When sheep from our previous study were 300 days old, both ES and IS were randomly assigned to either shift (ES-S and IS-S) or unshift conditions (ES-U and IS-U; n 5 6 in each group). Groups ES-S and IS-S were fed HQF (alfalfa hay) during the preshift phase, and then suddenly changed to LQF (oat hay) in the postshift phase. Groups ES-U and IS-U (controls) were fed only LQF throughout the SNC procedure. Subjects in ES-S showed a significantly lower intake of LQF than those in ES-U in the first postshift session (i.e. they showed an SNC effect), which was not observed in IS. These results agree with ES subjects having devalued LQF during early experience. We discuss the possibility that high levels of nutrient supplementation can result in devaluation of LQF (i.e. decrease in preference and acceptance), whereas restricted levels of supplementation may promote a positive experience with LQF.Keywords: early experience, food valuation, low-quality food, sheep, successive negative contrast ImplicationsEarly experience with specific foods can improve their acceptance and preference later in life. However, our past and present results with sheep suggest that mere exposure to foods in early life may not be sufficient to attain that outcome. Behaviour towards a food source and learning about its consequences depend not only on the food's intrinsic properties but also on the alimentary context in which it is presented. Current results can be interpreted as showing that the use of high levels of nutrient supplementation can cause a negative experience with LQF (i.e. a decrease in the preference and acceptance), whereas restricted levels of supplementation (a more typical scenario) may promote the opposite result (i.e. enhanced experience with LQF). IntroductionEarly food experience has the potential to increase food acceptance (voluntary intake of a given food) and preference (choices among food alternatives) in ruminants (Provenza and Balph, 1987;Distel and Provenza, 1991;Distel et al., 1994). Moreover, preference for low-quality f...

Translational Assessment of Reward and Motivational Deficits in Psychiatric Disorders

“…Accordingly, motivated behavior may be affected by disruptions in reward valuation. Reward valuation is highly conserved across species and has been observed in mice (Crombag et al , 2010; Hilario et al , 2007), rats (Balleine and Dickinson, 1992), sheep (Catanese et al , 2011), monkeys (Burke et al , 2014; West et al , 2011), and humans (Klossek et al , 2008). …”

Assessing the impact of supplements, food aversions, and silica on medusahead (Taeniatherum caput-medusae (L.) Nevski) use by sheep

“…It is likely that in these studies the sequence of presentation of palatable and unpalatable feeds (i.e., molasses applied directly to medusahead) led to a "simultaneous negative contrast" as opposed to an induction effect. A simultaneous negative contrast occurs when as a result of comparisons made among foods of different quality, animals show an exaggerated decrease in the intake of the lower quality options (Flaherty, 1996;Catanese et al, 2011).…”

A reappraisal of successive negative contrast in two populations of domestic dogs

“…Many mammals will show a reduction in instrumental or consummatory responses when they experience an unexpected shift from a higher to a lower quality and/or quantity of reward, relative to a control group that is exposed only to the lower-level reward (Papini et al 1988 ; Flaherty 1999 ; Mustaca et al 2000 ; Bergvall et al 2007 ; Catanese et al 2011 ). If the responses of the ‘downshifted’ subjects fall below those of animals who have only ever received the less preferred reward (‘unshifted’ subjects), the phenomenon is known as a successive negative contrast (SNC) effect (see Flaherty 1999 , for review).…”

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