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Selected Publication:

Type of publication: Journal Article
Type of document: Full Paper

Year: 2004

Authors: Arnold, W; Ruf, T; Reimoser, S; Tataruch, F; Onderscheka, K; Schober, F

Title: Nocturnal hypometabolism as an overwintering strategy of red deer (Cervus elaphus).

Source: Am J Physiol Regul Integr Comp Physiol. 2004; 286(1):R174-R181



Authors Vetmeduni Vienna:

Arnold Walter
Reimoser Susanne
Ruf Thomas
Schober Franz
Tataruch Frieda

Vetmed Research Units
Research Institute of Wildlife Ecology


Project(s): Impact of stress and energy metabolism of red deer and roe deer


Abstract:
Herbivores of temperate and arctic zones are confronted during winter with harsh climatic conditions and nutritional shortness. It is still not fully understood how large ungulates cope with this twofold challenge. We found that red deer, similar to many other northern ungulates, show large seasonal fluctuations of metabolic rate, as indicated by heart rate, with a 60% reduction at the winter nadir compared with the summer peak. A previously unknown mechanism of energy conservation, i.e., nocturnal hypometabolism associated with peripheral cooling, contributed significantly to lower energy expenditure during winter. Predominantly during late winter night and early morning hours, subcutaneous temperature could decrease substantially. Importantly, during these episodes of peripheral cooling, heart rate was not maintained at a constant level, as to be expected from classical models of thermoregulation in the thermoneutral zone, but continuously decreased with subcutaneous temperature, both during locomotor activity and at rest. This indicates that the circadian minimum of basal metabolic rate and of the set-point of body temperature regulation varied and dropped to particularly low levels during late winter. Our results suggest, together with accumulating evidence from other species, that reducing endogenous heat production is not restricted to hibernators and daily heterotherms but is a common and well-regulated physiological response of endothermic organisms to energetically challenging situations. Whether the temperature of all tissues is affected, or the body shell only, may simply be a result of the duration and degree of hypometabolism and its interaction with body size-dependent heat loss.

Keywords Pubmed: Acclimatization/physiology*
Animal Feed
Animals
Body Temperature Regulation/physiology
Circadian Rhythm*
Cold Temperature*
Deer/metabolism*
Energy Metabolism
Heart Rate/physiology
Hot Temperature
Motor Activity/physiology
Seasons*


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