Partition of heat loss in resting and exercising winter- and summer-insulated reindeer
Folkow, L.P.; Mercer, J.B.
American Journal of Physiology 251(1 Pt 2): R32-R40
1986
ISSN/ISBN: 0002-9513 PMID: 3728709 Document Number: 269680
Partition of heat loss was made in resting (standing) and exercising (running; 9.2 km/h for 40 min) winter- (W) and summer-insulated (S) conscious reindeer (Rangifer tarandus tarandus) in a climatic chamber set to an ambient temperature (Ta) of -30 degrees , 0 degrees or 25 degrees C. Heat loss and production were estimated using indirect calorimetry. The relative importance of radiant heat loss was greatest during rest at low Ta, during winter and summer (44 to 58% at Ta -30 degrees and 0 degrees ). At high Ta, especially during exercise, a large proportion of total heat loss occurred through evaporation [45% at Ta 25 degrees during rest and 47% at Ta 0 degrees during exercise (W); 38% at Ta 25 degrees during exercise (S)]. The proportion of heat lost through convection during rest and exercise was 38 to 52 and 46 to 72%, respectively, depending on Ta and season. The legs were an important site of radiant heat loss, particularly in heat stress situations. Their importance for convective heat loss was even greater, especially during exercise.