Harmon D L
Department of Animal Science and Industry, Kansas State University, Manhattan 66506.
J Anim Sci. 1992 Apr;70(4):1290-301. doi: 10.2527/1992.7041290x.
Because of the unique features of the ruminant digestive system, variations in diet composition and intake produce dramatic changes in ruminal fermentation. Optimizing nutritional management requires an understanding of how these variations and changes influence digestion and metabolism. Although the pancreas plays a central role in digestion and subsequent nutrient metabolism, relatively little is known about pancreatic adaptation to nutritional changes in the ruminant. Increasing starch intake has been suggested to increase pancreatic alpha-amylase; however, recent work suggests that dietary energy per se may drive these changes, and interactions with other nutrients, such as protein, may exist. Studies describing the influence of altered protein and lipid intakes on pancreatic adaptation in ruminants are lacking. Pancreatic secretion of both insulin and glucagon respond to the intravenous infusion of VFA in a dramatic fashion; however, feeding studies suggest that the influence of VFA on insulin and glucagon may be more subtle. Interactions exist between stimulatory signals and physiological state, such as lactation. Assessment of pancreatic endocrine secretion is further complicated by a variable removal of insulin and glucagon by hepatic tissues. These studies point out that pancreatic hormone secretion is controlled by integrated and complex mechanisms. Studies of these controlling mechanisms should consider the entire array to more fully understand hormone secretion.
由于反刍动物消化系统的独特特征，日粮组成和采食量的变化会引起瘤胃发酵的显著变化。优化营养管理需要了解这些变化如何影响消化和代谢。尽管胰腺在消化及后续营养物质代谢中起着核心作用，但关于反刍动物胰腺对营养变化的适应性却知之甚少。有人提出增加淀粉摄入量会增加胰腺α-淀粉酶；然而，最近的研究表明，日粮能量本身可能驱动这些变化，并且可能存在与其他营养素（如蛋白质）的相互作用。缺乏描述蛋白质和脂质摄入量改变对反刍动物胰腺适应性影响的研究。胰岛素和胰高血糖素的胰腺分泌对静脉输注挥发性脂肪酸（VFA）有显著反应；然而，饲喂研究表明，VFA对胰岛素和胰高血糖素的影响可能更为微妙。刺激信号与生理状态（如泌乳）之间存在相互作用。肝脏组织对胰岛素和胰高血糖素的可变清除进一步使胰腺内分泌分泌的评估变得复杂。这些研究指出，胰腺激素分泌受综合且复杂的机制控制。对这些控制机制的研究应考虑整个体系，以便更全面地了解激素分泌。
