[Prandial stimulation of reticular movements in sheep: cephalic phase and oral reflex (author's transl)]

Acceleration of reticular contractions when chewing feed (oral reflex of the reticulum, ORR) has been well documented for many years. The aim of the present investigation was to study the evolution of this reflex throughout the meal period. A possible triggering effect of drinking water was also investigated. Reticular contractions and chewing movements were simultaneously recorded from four sheep by means of permanent reticular wire electrodes and foam rubber balloons fastened below the lower jaw. Records were drawn before and during presentation of feed, then during the meal which followed. Similar records were drawn while sheep were drinking during intervals between feeding periods. In every case, intensity of mastication decreases from beginning up to the end of the feeding period. This decrease is paralleled by a slope of reticular frequency, which is very high at the beginning of the meal. The significant correlation between the two phenomena suggests that the decrease of the ORR results from a lesser stimulation of oral mechanoreceptors. Reticular movements are obviously accelerated during isolated drinking periods. Existence of a true cephalic phase of prandial reticular stimulation is evidenced by a moderate acceleration on the sole presentation of feed.