反刍动物胰液分泌调控与肠道胰酶稳态机制研究进展OA

In modern intensive farming,high-yield stress and changes in dietary composition often lead to relative insufficiency of pancreatic exocrine function in ruminants.Correspondingly,the small-intestinal starch digestibility only ranges from 35%to 60%.Fecal starch concentration shows a strongly negative linear correlation with total-tract starch digestibility with a maximum R2 value of 0.94;every 1-percentage-point rise in fecal starch reduces starch digestibility by approximately 1.25 percentage points,which substantially contributes to feed waste and abnormal hind-gut fermentation.This review firstly describes the complex regulatory network of ruminant pancreatic-juice secretion governed by neural path-ways,hormonal factors and the gut-pancreas axis.It further elaborates the subtle interactive mechanisms whereby dietary starch availability,functional amino acids and physical fiber properties modify pancreatic exocrine function,and summarizes existing nutritional strategies as well as their outcomes to improve pan-creatic performance.We propose that delayed cholecystokinin(CCK)responses resulting from low expres-sion of the cholecystokinin-B receptor(CCKBR)in pancreatic acinar cells serve as a species-specific trait distinguishing ruminants from monogastric animals.The recruitment and subsequent autolysis of pancreatic enzymes mediated by the T9SS secretion system of intestinal commensal Paraprevotella account for the major pathway for declining pancreatic-enzyme activity within the hindgut.We conclude that limitations from both secretion and degradation jointly restrict small-intestinal digestive capacity of ruminants.Accord-ingly,we put forward combinational interventions including precise diet formulation,targeted supplementa-tion of functional amino acids and exogenous enzyme provision.This work provides theoretical support for optimizing pancreatic function and feed-utilization efficiency via nutritional manipulation in ruminant pro-duction.