Metabolic Rate is Most Stable at Thermoneutral Zone

Austin Foxworth, John Clymer, Michael Cobbs


We are testing the effect of different temperatures on mice’s metabolic rate based off of CO2 and O2 consumption levels. The amount of food consumed and activity level depends on the animals’ metabolic rates, which may or may not be affected by temperature. Metabolizing cells perform bodily functions using the energy that the cells receive from food. At changing rates, this energy can be spent rapidly (Hoefnagels 664). Previous work has failed to address the change in O2 and CO2 as the temperature decreases and increases. It is important to note that mice, like most organisms, have upper and lower critical temperatures. Upper critical temperature, or critical thermal maximum, is the maximum body temperature that can be tolerated by an organism, most animal’s upper critical point lies between 30°C and 45°C ( We decided to control the temperature of the mice’s thermal surroundings and measure their O2 intake and CO2 production. Mice are also endotherms. We performed this experiment by placing the mice in temperature chambers and using O2 and CO2 probes to measure the levels in order to find their metabolic rates. We found that the animals are most stable in their thermal neutral zone, at room temperature. Small nocturnal rodents face a problem in temperature regulation in cold environments because of their large surface to volume ratio and associated higher metabolic rate (Vickery 1981). 

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