Effects of fiber on nutrient digestion in the intestine of sheep nourlished by intragastric infusion

本研究旨在探讨影响灌胃营养绵羊下肠道淀粉、蛋白质和矿物质消化利用的因素。试验一将四种不同水平的纤维素注入皱胃，研究肠道中淀粉和蛋白质的消化以及氮和矿物质在动物体内的滞留。试验二研究了不同挥发性脂肪酸(VFA)组成和不同VFA灌注量对淀粉和蛋白质消化及氮存留率的影响。结果：(1)蛋白质表观消化率较小。肠道氮随纤维素输入量的增加而减少，这是因为高纤维输入量增加了内源肠道氮的含量。(2)蛋白质在小肠和大肠的消化率不受VFA组成和VFA水平的影响，但高丙酸比例的VFA混合物提高了氮的存留率。(3)淀粉在小肠中的消化率不受纤维素水平的影响，但受VFA混合物的影响。灌注量与小肠淀粉消化率呈显著正相关。(4)钙、镁和无机磷对粪便排泄量、血清滞留率和血清浓度的影响不受纤维素水平的影响。

The purpose of this study is to elucidate factors affecting the digestion and the utilization of starch, protein and minerals in the lower gut of sheep nourished by intragastric infusions. In experiment 1, four levels of cellulose were infused into the abomasum to investigate the digestion of starch and protein in the intestine, and the retentions of nitrogen and minerals in the animals. In experiment 2 the effects of volatile fatty acid (VFA) composition and VFA infusion levels on the digestion of starch and protein and the nitrogen retention were investigated. Results: (1) The protein apparent digestibility in the small. intestine decreased with the increase of infused cellulose, since the endogenous intestinal nitrogen increased in the high cellulose infusion level. (2) The protein digestibility in the small and large intestine was not influenced by VFA composition or VFA level, but the nitrogen retention increased during the infusion of VFA mixtures of high propionic acid ratio. (3) The starch digestibility in the small intestine was not influenced by the cellulose levels, but influenced by the VFA mixtures. There is a significant positive correlation coefficient between the quantity of infused acetic acid and the starch digestibility in the small intestine. (4) Calcium, magnesium and inorganic phosphorus on the fecal excretion, the retention and the concentration of blood serum were not influenced by the cellulose levels.