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

膳食淀粉对于单胃物种来说是一种令人着迷的营养物质。由于理化特性的变化，淀粉的种类从低直链淀粉到高直链淀粉不等，从上部肠道可快速消化到下部肠道可发酵。因此，淀粉可以作为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饲粮因素，因为它的发酵和对全身养分利用的抑制作用。相比之下，在人类营养学中，可发酵或抗性淀粉因其抑制营养吸收速度和刺激肠道健康而越来越受欢迎。存在于整个肠道的将新陈代谢从快速消化的淀粉改变为可发酵的淀粉的潜在机制还知之甚少，但包括营养转运体、化学感应器、肠道结构和通透性的变化，以及向胰腺发出的胰岛素信号。为了阐明这些机制的改变，将使用1)远端回肠插管收集消化，2)门静脉插管顺序采集血液，3)屠宰法收集肠道组织和消化，4)间接量热法。这种组合可以测量淀粉消化的总程度、速度和位置，以及全身能量和营养的利用。最后，可以研究淀粉流动对维持肠道结构的影响以及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不同理化性质的精制饲料淀粉的可用性相结合是独特的，是研究淀粉及其代谢物流动动力学及其对消化生理影响的强大工具。拟议的工作加强了我们的努力，将膳食碳水化合物与一系列广泛的营养和生理变量联系起来，并评估碳水化合物对全身营养利用的消极和积极影响。这项拟议的工作对于更好地预测和管理猪的营养流动具有重要意义。最后，这项工作促进了对加拿大谷物和豆类中所含淀粉进行分级和表征的努力，为加拿大农业食品行业创造了机会。

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.