AJP - Regulatory, Integrative and Comparative Physiology, Vol 251, Issue 1 32-R40, Copyright © 1986 by American Physiological Society
Partition of heat loss in resting and exercising winter- and summer-insulated reindeer
L. P. Folkow and J. B. Mercer
Partition of heat loss was performed in resting (standing) and exercising
(running; 9.2 km . h-1 for 40 min) winter- (W) and summer- (S) insulated
conscious reindeer (Rangifer tarandus tarandus) in a climatic chamber set
to an ambient temperature (Ta) of -30, 0, or 25 degrees C. Heat loss and
production were determined using indirect calorimetry. The relative
importance of radiant heat loss was greatest during rest at low Ta's, both
during winter and summer (44-58% at Ta's -30 and 0 degrees C). At high
Ta's, especially during exercise, a large proportion of total heat loss
occurred through evaporation [45% at Ta 25 degrees C during rest and 47% at
Ta 0 degrees C during exercise (W); 38% at Ta 25 degrees C during exercise
(S)]. The proportion of heat lost through convection during rest and
exercise was 38-52 and 46-72%, respectively, depending on Ta and season.
The legs were found to represent an important avenue for radiant heat loss,
particularly in heat stress situations. Their importance for convective
heat loss was even greater, especially during exercise.
