AJP - Regulatory, Integrative and Comparative Physiology, Vol 257, Issue 6 1328-R1334, Copyright © 1989 by American Physiological Society
Ambient temperature and food costs: effects on behavior patterns in rats
G. H. Collier, D. F. Johnson, J. Naveira and K. A. Cybulski
Department of Psychology, Rutgers, State University of New Jersey, New Brunswick 08903.
Eating, drinking, wheel running, and nesting were recorded continuously in
animals living in cages where they foraged for and consumed food by
completing operant bar-press requirements. The ambient temperature was
either 24 or 0 degrees C. Two food costs, that of initiating meals and that
of pellets within meals, were separately manipulated at each temperature.
Compared with room temperature, the cold temperature produced a doubling of
food and water intake and a greater than twofold increase in nesting time
each day. Running behavior was not altered. Regardless of temperature, the
cost of initiating meals influenced the frequency and size of meals but did
not affect total food intake or time spent feeding, and this cost had no
effect on any other activity. As the cost of pellets within meals
increased, the time spent feeding increased and there was a decline in
daily food intake. The change in intake was greater at the cold temperature
because in the cold the rats did not increase daily feeding time
sufficiently to maintain intake as pellet cost increased. Such an increase
in feeding time would have required that less time be spent in one of the
other activities.
