Impact of physico-chemical properties of dietary starch on digestive physiology in pigs

膳食淀粉是单胃物种的一种迷人的营养素。从低直链淀粉到高直链淀粉的淀粉，由于理化特性的变化，在上消化道中可快速消化，在下消化道中可发酵。因此，淀粉可以是葡萄糖或短链脂肪酸（SCFA）的来源。在猪营养学中，可发酵淀粉是一种负面的饮食因素，因为它对全身营养利用的发酵和抑制作用。相反，在人类营养中，可发酵或抗性淀粉由于其抑制营养吸收速率和刺激肠道健康而越来越受欢迎。存在于整个肠道中的将代谢从快速消化淀粉改变为可发酵淀粉的潜在机制知之甚少，但包括营养转运蛋白、化学传感器、肠道结构和通透性以及胰促肠激素信号传导的变化。为了阐明这些机制变化，将使用猪模型，包括1）远端回肠插管以收集回肠，2）门静脉插管以顺序采集血液，3）屠宰方法以收集肠组织和回肠，以及4）间接热量测定法。这种组合允许测量淀粉消化和全身能量和营养利用的总程度、速率和部位。最后，可以研究淀粉流对维持肠道结构的影响和未消化淀粉对微生物种群的影响。四种不同的猪研究模型和纯化膳食淀粉的可用性在其物理化学性质方面是独特的，并且是研究淀粉及其代谢物流动动力学及其对消化生理学的影响的强大工具。拟议的工作加强了我们将膳食碳水化合物与广泛的营养和生理变量联系起来的努力，并评估了碳水化合物对全身营养利用的负面和正面影响。这项工作对于更好地预测和管理猪的营养流具有重要意义。最后，这项工作促进了加拿大谷物和豆类中所含淀粉的破碎和表征，为加拿大农业食品工业创造了机会。

Dietary starch is a fascinating nutrient for monogastric species. Starches ranging from low to high amylose range from rapidly digestible in the upper gut to fermentable in the lower gut due to changes in physico-chemical characteristics. Starch can thus be a source of glucose or short-chain fatty acids (SCFA). In swine nutrition, the paradigm is that fermentable starch is a negative dietary factor due to its fermentation and suppressive effects on whole body nutrient utilization. In contrast, in human nutrition, fermentable or resistant starch is gaining popularity due to its suppression of the rate of nutrient absorption and stimulation of intestinal health. The underlying mechanisms that exist throughout the intestine to change metabolism from rapidly digestible starch to fermentable starch are poorly understood, but include changes in nutrient transporters, chemo-sensors, gut structure and permeability, and incretin signalling to the pancreas. To clarify these mechanistic changes, pig models including 1) distal ileum cannulation to collect digesta, 2) portal-vein catheterization to sequentially sample blood, 3) slaughter method to collect intestine tissue and digesta, and 4) indirect calorimetry will be used. This combination allows measuring of total extent, rate, and site of starch digestion and whole body energy and nutrient use. Finally, the effects of starch flow on maintenance of intestinal structure and of non-digested starch on microbial populations can be studied. The combination of four distinct pig research models and the availability of purified dietary starches ranging in their physico-chemical properties is unique and is a robust tool to study the kinetics of flow of starch and its metabolites, and their impact on digestive physiology. The proposed work strengthens our efforts to link dietary carbohydrates to a wide array of nutritional and physiological variables, and to assess negative and positive effects of carbohydrates on whole body nutrient utilization. The proposed work is important to better predict and manage nutrient flow in pigs. Finally, the work stimulates efforts to fractionate and characterize starch contained in Canadian cereals and pulses, creating opportunities for Canadian agri-food industries.