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

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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.