Regulation of pancreatic exocrine secretion in ruminants: a review.

Mechanisms regulating ruminant pancreatic exocrine function differ in some respects from those in nonruminants. This may affect the post-ruminal digestion of certain dietary nutrients such as starch. Ruminants do not exhibit clearly defined cephalic and gastric phases of pancreatic regulation, a likely consequence of the continuous nature of digesta flow from the rumen. Local neural reflexes and secretin-mediated exocrine responses may be more important than stimulation by cholecystokinin. Additionally, the ruminant pancreas may be stimulated by short-chain fatty acids produced in the rumen. A "ruminal phase" of pancreatic exocrine regulation has been proposed. The failure of cattle to digest efficiently starch in the small intestine may result from an asynchrony between delivery of starch to the intestines and pancreatic amylase release.