Kinetics of Dietary Fibers in a Fat Sand Rat: The Importance of the Isolating Structures of the Digestive Tract and Food Quality

The passage of food through the digestive tract in an herbivorous rodent with a single-chamber semiglandular stomach, the fat sand rat Psammomys obesus, was studied by multiple marking of the food with inert plastic markers. The total mean retention time of markers in the digestive tract (DT), as well as in the stomach and caecum separately, was determined. The peculiarities of the digesta kinetics depending on the morphology of the digestive tract, diet, and the time of marker intake were clarified. The total time for removal of markers from the DT in the fat sand rat reaches 36 h. The mean retention time of markers in the DT was determined as a whole (17–18 h), as well as separately in the forestomach (7–9 h) and caecum (7–12 h). The uneven passage of feed has been revealed, which is considered as an important mechanism for maximizing the extraction of nutrients from plants, including microbial fermentation of structural carbohydrates of the food.