[Effects of a diet with various protein contents on the life span of rats]

A study was made of the effects of 3 food diets containing 22, 12 and 12% of protein (the latter diet included hydrolysates) on the lifespan of old animals. Protein metabolism was studied concurrently from excretion of nitrogenous metabolism products with urine, from the level of free amine acids in the tissues, the content of proteins and its fractions in the blood serum, and urea in the tissues. The biological value of the diets proposed was estimated in experiments on young animals. The mean lifespan of old animals was found to decrease if the animals were fed the diet containing protein hydrolysates.