Candidate prebiotics available for human consumption and animal nutrition represented a numerous and diverse group of substances with different amount of bifidogenic oligosaccharides (20-90% of dry matter). The application of prebiotic preparation caused a decrease in the energy value of diets, however the body weight gain of an animal remained unchanged with increased diet intake. One of the effects of oligosaccharide addition to a diet is an increase in the amount of digesta in the gastrointestinal tract, including caecum, which in turn lowers concentration of major products of oligosaccharide fermentation - short-chain fatty acids in fresh caecal digesta. Therefore, total SCFA pool in the whole caecum (converted into 100 g of body weight of rats) is a better indicator of the intensity of oligosaccharide fermentation in the large bowel. The content of probiotic preparations in a diet differentiates the activity of microbial enzymes (mainly α-and β-lactosidase as well α- and β-glucosidase) in the caecal digesta.