Mechanisms of intake induction of a low-nutritious food in sheep (Ovis aries)

FREIDIN, E.; CATANESE, F.; DIDONÉ, N.; DISTEL, R.A.

BEHAVIOURAL PROCESSES

ELSEVIER SCIENCE BV

Año: 2011 vol. 87 p. 246 - 252

0376-6357

Intake induction refers to the phenomenon in which animals increase the consumption of a less-valued meal when followed by a highly-preferred food than when followed by no food or the same less-preferred food. In the Training phase of the present experiment, we assessed the induction effect in sheep using a within-subject design where learning could be tested while controlling for digestive state. Results showed that, once consumption reached stability, subjects ate more oat hay (low-nutritious food) when followed than when preceded by soybean meal (preferred food), supporting the learning hypothesis. The second, Revaluation, phase of the experiment had the goal of exploring the associative mechanism of induction, for which we paired gastric malaise caused by lithium chloride intoxication with consumption of soybean meal or a control food. Despite subjects partially rejecting soybean meal relative to controls after the aversive conditioning protocol, oat hay consumption seemed unaffected by soybean meal devaluation. We conclude that intake induction in sheep may rely on changes in hedonic properties of the low-nutritious food based on its association with post-ingestive feedback from the preferred food (hedonic hypothesis), but not on an explicit anticipation of the latter (signalling hypothesis).