Abstract # 921 Poster # 181:

Scheduled for Friday, August 19, 2005 07:00 PM-09:00 PM: (Cambridge/Oxford Room) Poster Presentation

Energy Expenditure Resulting from Physical Activity is Similar in Female Rhesus Monkeys (Macaca mulatta) Housed in Group Pens vs. Single Cages

E. L. Sullivan1,2, F. H. Koegler1 and J. L. Cameron1,2
1Oregon National Primate Research Center, 505 NW 18th Avenue, Beaverton, Oregon 97006, USA, 2Department of Physiol & Pharmacol, Oregon Health Sciences University
     To test the difference in energy expenditure resulting from physical activity in single-caged versus group housed monkeys, we measured physical activity by accelerometery in adult female rhesus monkeys housed in single cages (n = 17) and group pens (n = 12, 3.66m x 3.66m x 4.27m, with 1-4 other monkeys). Accelerometers were mounted on collars. We found no difference in activity in monkeys living in single cages (281,000 activity counts/day) versus group pens (324,000 activity counts/day, P = 0.53). As activity is increasingly recognized as an important variable in the regulation of body weight, we further calibrated the accelerometers to determine the energy expenditure represented by each activity count. Monkeys housed in single cages were placed for a day in a metabolic cage and energy expenditure was measured by indirect calorimetry. Energy expenditure due to activity was calculated by subtracting basal metabolic rate from total energy expenditure at two times during the day, 2-3 PM and 6-7 PM. Energy expenditure due to physical activity per kilogram of body weight was calculated as 0.71 + 0.003*activity counts/hour. Results were similar at both times of day. Monitoring physical activity will be of interest to an increasing number of scientists as it is affected by many variables (sex, reproductive status, dominance rank, season), and its influence on an increasing number of physiological systems, including brain function, is becoming evident.