Using a laboratory colony we demonstrated that the body mass (BM) and reproductive organ mass (ROM) of Brandt's voles vary in response to photoperiod and temperature. Male Brandt's voles from 25 days of age were housed under long (14L) or short (10L) photoperiod, which corresponds to seasonal changes in their natural environment. Under 10L, animals housed for the first 7 weeks at 10°C were significantly lighter than those housed at 20°C. This effect was not observed under 14L. However, a change from an initial 10L photoperiod to the 14L photoperiod for the following 9 weeks could compensate the effects of low temperature on BM. Changes in BM in response to photoperiod and/or temperature exposure appeared to be primarily as a result of the deposition or loss of fat-free dry mass and water. For Brandt's voles, ROM was regulated significantly by photoperiod but not by temperature. Taken together, the results suggest that BM and ROM for male Brandt's voles respond selectively to photoperiodic information and temperature. We propose that a compensatory relationship between photoperiod and temperature should be considered in animal physiology research.
©2010 by Walter de Gruyter Berlin New York