Meeting Abstract
P3.83 Monday, Jan. 6 15:30 The energetics of communal torpor in Siberian hamsters JEFIMOW, M.*; DYLEWSKA, E.; BORATYNSKI, J.S.; WOJCIECHOWSKI, M.S.; Nicolaus Copernicus Univ., Torun, Poland; Nicolaus Copernicus Univ., Torun, Poland; Nicolaus Copernicus Univ., Torun, Poland; Nicolaus Copernicus Univ., Torun, Poland jefimow@umk.pl
Huddling may bring about significant benefits in terms of animal’s energy expenditure. We tested whether living in groups and huddling affect the costs of daily torpor and the costs of rewarming in winter-acclimated Siberian hamsters (Phodopus sungorus). Study animals were housed singly, in pairs, and in groups of 3 or 4 siblings and were acclimated to winter-like conditions (short photoperiod L8:D16 and cold 10°C) for 3 months to induce daily torpor. Hamsters were implanted intraperitoneally with miniature data loggers to record body temperature (Tb) throughout the experiment. At the time of maximum torpor frequency we measured their metabolic rate (MR) for ~24 hours at 10°C using indirect calorimetry. Half of animals measured singly and more than half measured in groups entered torpor during MR recordings. Additionally, in 8 trials we recorded spontaneous arousals. Data were analyzed using GLM procedure. We found that mean torpor bout duration and Tb in torpor were similar in single and grouped hamsters. Compared to resting MR, MR during steady-state torpor was reduced by ~64% in grouped hamsters and by ~82% in singles. MR during steady-state torpor (at the duration: 239.8 min, and body mass, mb = 28.6 g) was similar in grouped and in single hamsters (0.18 ± 0.02 vs. 0.20 ± 0.03 W). However, the total cost of arousal per individual, at mean mb = 28.9 g, was 21.61 ± 5.09 W in grouped animals and 30.17 ± 5.09 W in solitary hamsters. When grouped-housed hamsters were measured individually, the cost of arousal increased to the level recorded in the single-housed animals. These results indicate that communal torpor in the Siberian hamsters does not affect MR during steady-state torpor but this behavior may reduce the cost of arousal.
