Movements of the stomach compartments of a young bull during sucking

1. Gastric motility was studied in a young bull and two sheep which had retained their sucking behaviour. Pressure tracings or electromyograms were recorded from all compart-ments of the stomach. 2. During the sucking of milk or water reticulum contractions either became more fre-quent but weak, or ceased altogether. After sucking, or after the introduction of fluid directly into the abomasum, reticulum contractions slowed down but retained their strength. The rumen and omasum were more fully inhibited than the reticulum. 3. It is concluded that the inhibitory response to sucking has two phases, a cephalic phase dependent upon the eagerness of sucking which mainly influences the strength of the contractions of the forestomach, and an abomasal phase dependent on the degree of distension of the abomasum which mainly affects the frequency of the contractions.