When removed from the field and maintained under laboratory conditions, meadow voles exhibited significant change in body composition. Voles increased body mass due primarily to large gains in lipid mass combined with small losses in fat-free mass. Lipid deposition amounts increased as dietary fat was increased, and animals demonstrated a leveling of body mass instead of continuous unregulated obesity. When dietary fat content was changed, lipid deposition or utilization responded directly. Thus, meadow voles regulate overall body mass and body composition (lipid and fat-free mass) at levels that correspond to dietary quality (fat) and abundance in the laboratory, and they deposit considerably more lipid than do animals in the field. Our experiments demonstrate that food quality has a substantial effect on the body composition of wild-caught animals maintained in the laboratory.
Unangst, Edward T. Jr. and Wunder, Bruce A.
"Laboratory fattening and dietary-fat effects on meadow voles (Microtus pennsylvanicus),"
Western North American Naturalist: Vol. 63
, Article 12.
Available at: http://scholarsarchive.byu.edu/wnan/vol63/iss1/12