Hyperphagia induced by pylorectomy in sheep.

In the hay-fed sheep, gastric (abomasal) contents are delivered continuously into the duodenal bulb at a mean flow rate of 210 ml per hour. The pylorus could behave as the site of origin of a feedback satiety signal by acting as a distal stomach sphincter limiting the abomasal emptying rate. This ability of the pyloric sphincter was confirmed by enhancement of abomasal outflow following either pylorectomy or pyloroplasty. In both cases, the subsequent reduction of the mean residence time of digesta in the abomasum was accompanied by an increase in the voluntary intake. The increase by 48% of food intake persisted several weeks after pylorectomy and was not only compensatory for the lower intake during recovery from surgery. Such an hyperphagia, obtained by removal of the ruminant herbivore pylorus, suggests the suppression at the antroduodenal junction level of a regulating factor affecting voluntary food intake by modulating the mean residence time of digesta in the abomasum.