Clemens E T, Stevens C E, Southworth M
J Nutr. 1975 Jun;105(6):759-68. doi: 10.1093/jn/105.6.759.
Twelve swine were used to assess the movement of fluid and particulate digesta through their gastrointestinal tracts and to determine the diurnal variations in organic acid levels for various segments of the tract. Animals were fed twice daily at 12-hour intervals. Fluid (polyethylene glycol and chromium-labeled ethylenediamine-tetraacetic acid) and particulate markers (2 mm OD, and 2 mm and 1 and 2 cm long) were administration of markers. The gastrointestinal tract was divided into 12 segments for measurements of markers, pH, volatile fatty acids (VFA), and lactic acid (LA) contents. The data indicated a rapid evacuation of the fluid and the smaller particles from the stomach and their relatively rapid passage through the small intestine and cecum. There was, however, prolonged retention of both fluid and particulate markers first in the ascending and then in the descending colon. Larger particles (2 cm) were retained in the stomach throughout much of the 60-hour experimental period. LA levels were observed 8 hours postfeeding. The highest levels of VFA in gastric contents averaged 20 mmoles/liter. Gastrointestinal pH values showed significant changes with time postfeeding only within the stomach, where they did not reflect the changes in LA of VFA concentrations. VFA constituted 92% of the organic acids present in the large intestine. Their concentrations varied markedly with time (150-230 mmoles/liter), but the VFA at all times constituted the major anions in the large intestinal contents. The results demonstrated that digesta can be retained for prolonged periods of time in that swine stomach and colon. The high concentrations of organic acids also indicated that substantial degrees of microbial digestion of carbohydrates occurred at both sites.
选用12头猪来评估液体和颗粒性食糜在其胃肠道中的移动情况，并确定胃肠道各段有机酸水平的昼夜变化。动物每天定时投喂两次，间隔12小时。通过给予液体（聚乙二醇和铬标记的乙二胺四乙酸）和颗粒性标志物（外径2毫米、长2毫米以及1厘米和2厘米）来进行标志物的施用。胃肠道被分为12个段，用于测量标志物、pH值、挥发性脂肪酸（VFA）和乳酸（LA）含量。数据表明，液体和较小颗粒从胃中迅速排空，并相对快速地通过小肠和盲肠。然而，液体和颗粒性标志物首先在升结肠，然后在降结肠中滞留时间延长。较大颗粒（2厘米）在60小时的实验期大部分时间内都滞留在胃中。在喂食后8小时观察到LA水平。胃内容物中VFA的最高水平平均为20毫摩尔/升。胃肠道pH值仅在胃内随喂食后时间发生显著变化，且这些变化并未反映VFA浓度的LA变化。VFA占大肠中存在的有机酸的92%。它们的浓度随时间显著变化（150 - 230毫摩尔/升），但VFA在任何时候都是大肠内容物中的主要阴离子。结果表明，食糜在猪的胃和结肠中可长时间滞留。高浓度的有机酸还表明，碳水化合物在这两个部位都发生了大量的微生物消化。
