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

Year: 2011

Authors: Turbill, C; Ruf, T; Mang, T; Arnold, W

Title: Regulation of heart rate and rumen temperature in red deer: effects of season and food intake.

Source: J Exp Biol. 2011; 214(Pt 6):963-970



Authors Vetmeduni Vienna:

Arnold Walter
Ruf Thomas
Turbill Christopher

Vetmed Research Units
Research Institute of Wildlife Ecology


Project(s): Food and winter hypometabolism of red deer


Abstract:
Red deer, Cervus elaphus, like other temperate-zone animals, show a large seasonal fluctuation in energy intake and expenditure. Many seasonal phenotypic adjustments are coordinated by endogenous signals entrained to the photoperiod. The cues determining variation in the resting metabolism of ungulates remain equivocal, however, largely because of the confounding effects of food intake and thus the heat increment of feeding. To distinguish endogenous seasonal and environmental effects on metabolism, we subjected 15 female red deer to two feeding treatments, 80% food restriction and low/high protein content, over two winter seasons in a cross-over design experiment. We used rumen-located transmitters to measure heart rate and rumen temperature, which provided indices of metabolism and core body temperature, respectively. Our mixed model (R²=0.85) indicated a residual seasonal effect on mean daily heart rate that was unexplained by the pellet food treatments, activity, body mass or air temperature. In addition to an apparently endogenous down-regulation of heart rate in winter, the deer further reduced heart rate over about 8 days in response to food restriction. We found a strong correlation between rumen temperature and seasonal or periodic variation in heart rate. An effect of lowered rumen (and hence core body) temperature was enhanced during winter, perhaps owing to peripheral cooling, which is known to accompany bouts of hypometabolism. Our experimental results therefore support the hypothesis that a reduction in body temperature is a physiological mechanism employed even by large mammals, like red deer, to reduce their energy expenditure during periods of negative energy balance.

Keywords Pubmed: Analysis of Variance
Animals
Body Temperature/physiology*
Circadian Rhythm/physiology
Deer/physiology*
Feeding Behavior/physiology*
Female
Heart Rate/physiology*
Linear Models
Rumen/physiology*
Seasons*


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