Relation between average daily metabolic rate and resting metabolic rate of the mongolian gerbil (Meriones unguiculatus).

Some early reports have claimed that the Mongolian gerbil is a diurnal rodent, but we found it to be active both night and day, being more active at night. A circadian rhythm was found both in locomotory activity under laboratory conditions and in average daily metabolic rate (ADMR).The ADMR of the Mongolian gerbil observed at 20° C in our study was 2.921 ml O2/g·h which was near the value expected from Grodzinski's equation (ADMR=19.94 W-0.50).Both ADMR and RMR were found to be negatively correlated with ambient temperature, with the slope of the regression line for ADMR being less than that for RMR. These two lines intersected at 20° C, lower below 20° C.According to Grodzinski, the ADMR is usually lower than RMR, but in our study the ADMR was found to be lower than the RMR only below 20° C, which suggests that the ambient temperature acts differently on ADMR and RMR. The temperature-dependent variation of both ADMR and RMR as well as their differences should be taken into account in the estimation of the productivity of animal population.