[The effect of the protein content of the diet on the resting and fasting oxygen consumption of albino rats].

The influence of the dietary protein concentration on the resting and fasting oxygen consumption (RNSV) was investigated on 71 male Wistar rats, at an environmental temperature of 28 degrees C. At the beginning of the first experiment the animals were either one, three or eight months old and weighed approximately 100, 300 or 500 g. They received a purified diet, containing a crude protein concentration of either 7 or 20%, for eight weeks; the protein carrier was wheat gluten. In the second experiment, carried our directly after the first one, only the animals weighing 500 g received Altromin stock diet for three weeks. Experiments on growing animals with different dietary protein concentrations, lead to considerable weight differences. Since the RNSV depends on the body mass, the experiments must be conducted in such a manner that the animals are of the same age, the same weight, and have been adapted to the diet for at least two weeks at the time the RNSV is measured. The experiments have shown that quantitative protein deficiency causes a greater reduction of the RNSV, the lighter or younger the animals are. On the other hand they have shown that the intraspecific relation between RNSV and body mass depends on the protein concentration of the diet. Consequently, this causes the value of the intraspecific body mass exponent to grow with a decrease in the dietary protein concentration, which in turn limits the animals growth. The results of this investigation cannot be explained by diet induced thermogenesis (DIT) of proteins. However, they support the hypothesis that quantitative protein deficiency decreases the calorigenic action of the thyroid gland.