Abstract Food administration is followed by the appearance of a small intestinal pattern of irregular contractions. Studies on the relationship between intestinal motor activity, transit and absorption have yielded contradictory results. Since previous studies have shown that casein and casein hydrolysate led to a decrease of small intestinal motor activity and transit, the aim was to evaluate the effect of these nutrients on small intestinal motility and D‐Xylose absorption. Studies were performed in five dogs with a duodenal fistula; motility was recorded by means of six infused catheters and external transducers. Three test solutions with the same osmolality, lactulose, casein and casein hydrolysate, were continuously infused through the duodenal cannula. D‐Xylose was injected in the duodenum and plasma levels determined at regular intervals. Absorption of D‐Xylose was greatest during the administration of casein hydrolysate, the lowest levels were seen with lactulose and intermedia