Dietary protein life-span, and physiological variables in female mice.

The 50% mortality of female C57BL/6J mice fed ad libitum a diet which contained 26% or 4% casein, was 23.5 and 28 mo., respectively. Significantly lower rectal temperatures and higher oxygen consumptions were observed in the animals offered the 4% compared to the 26% casein diet. Changes in body temperature and oxygen consumption could not account for the total increase in life-span brought about by feeding a low protein diet.