Wheel running of kangaroo rats, Dipodomys merriami, as related to food deprivation and body composition.

Kangaroo rats deprived of food ran themselves to death in 48 h in wheel cages. Despite the loss of 14.5% of body weight the ratio of water to protein was the same after the run as it was in control rats. Metabolic measurements at rest and in the running wheel and weight loss in the 48-h run were used to estimate fuels used and water expended. Two-thirds of the initial amount of fat and 9% of the protein were metabolized. The terminal mean percentage of body fat was about twice that observed in rats trapped in the spring of 1967, when seed production was low: death in the 48-h run could not have been due to depletion of body fat alone. The powerful activity drive seen in hungary kangaroo rats presumably is intensified in dry years when food is scarce and may deplete their reserves enough to result in death from starvation.