Devaluation of low-quality food during early experience by sheep

CATANESE, F; FREIDIN, E; CUELLO, M; DISTEL, R

ANIMAL

CAMBRIDGE UNIV PRESS

Año: 2010

1751-7311

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) (Catanese et al. in press). A possibility is that ES might have devaluated the LQF through continuous comparisons against highly-quality food (HQF) supplements (sunflower meal and ground corn) that were simultaneously available during early experience. In the present 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 consumption of “unshift” subjects which receive LQF all throughout the SNC procedure. The magnitude of that difference 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=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 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 a SNC effect), which was not observed in IS. These results provided support for the devaluation of LQF by ES. We conclude that comparisons among foodstuffs in the early nutritional environment can affect how sheep value these foods in adulthood.