RESUMEN
Starting from 15 days of age the rats were transferred to formula feeding with liquid diet adapted to the rat milk composition in terms of the main parameters. It was shown that caseine exclusion from the rat diet during the early postnatal period of the development and its replacement by proteins of milk serum or by bovine serum albumin that are not capable of curdling leads to a 2- and 3-fold increase, respectively in the protein evacuation rate from the stomach. As a result, the nitrogen content in the chyme of the small intestine rises. One may think that observed accumulation of protein proteolysis products indicates both considerable intensity of cavitary digestion of proteins qualitatively different from caseine in the small intestine of rats in the early postnatal period of the development and its functional overloading as a result of which the protein proteolysis products formed fail to be absorbed.