The role of the pylorus in the ingestive capacity of the ruminant

Abstract

The pylorus, which means door keeper, is a variable orifice with unknown influences on the abomasal outflow in ruminants. By means of echography, particles are seen ejected as successive spurts, the volume of which being dependant upon of the size of the orifice. The pressure gradient developed by the contractions, the degree of their coordination and the viscosity of the liquid phase are major factors involved in the velocity of the outflow. The role of the pyloric sphincter in voluntary intake is demonstrated by increase of intake following pylorectomy as well as pyloroplasty. Both gastrokinetic substances and rheologic properties of the chyme are able to facilitate gastric outflow.