[Milk protein digestion in the stomach at an early age]

In the mucosa and gastric contents of young rats proteolytic activity was investigated. The pepsinogen content in the mucosa and proteolytic activity of the gastric contents does not change over a period from the 1st till the 11th day and then abruptly increase. A change-over from milk to mixed nourishment in the period from 12 to 20 days of life is attended by a growing pepsinogen content and a drastically reduced prorennin content in the gastric mucosa. The change-over from mixed to a definitely fixed nutrition after 20 days of life is accompanied by an intensive discharge into the gastric content of HCl and pepsin.