title: Estimating resting metabolic rate by biologging core and subcutaneous temperature in a mammal.
abstract: Tri-axial accelerometry has been used to continuously and remotely assess field metabolic rates in free-living endotherms. However, in cold environments, the use of accelerometry may underestimate resting metabolic rate because cold-induced stimulation of metabolic rate causes no measurable acceleration. To overcome this problem, we investigated if logging the difference between core and subcutaneous temperatures (ΔTc-s) could reveal the metabolic costs associated with cold exposure. Using implanted temperature data loggers, we recorded core and subcutaneous temperatures continuously in eight captive rabbits (Oryctolagus cuniculus) and concurrently measured their resting metabolic rate by indirect calorimetry, at ambient temperatures ranging from -7 to +25°C. ΔTc-s showed no circadian fluctuations in warm (+23°C) or cold (+5°C) environments implying that the ΔTc-s was not affected by an endogenous circadian rhythm in our laboratory conditions. ΔTc-s correlated well with resting metabolic rate (R(2)=0.77) across all ambient temperatures except above the upper limit of the thermoneutral zone (+25°C). Determining ΔTc-s could therefore provide a complementary approach for better estimating resting metabolic rate of animals within and below their thermoneutral zone. Combining data from accelerometers with such measures of body temperature could improve estimates of the overall field metabolic rate of free-living endotherms.
authors: Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg 2193, South Africa; Université de Lyon, Laboratoire de Biométrie et Biologie Evolutive, CNRS-UMR 5558 Université Lyon 1, 43 Bvd 11 Novembre 1918, F-69622 Villeurbanne Cedex, France. Electronic address: benjamin.rey@univ-lyon1.fr.
authors: Benjamin
authors: B
authors: Rey
authors: Department of Life Sciences, University of Roehampton, Holybourne Avenue, London SW15 4JD, United Kingdom.
authors: Lewis G
authors: LG
authors: Halsey
authors: Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg 2193, South Africa.
authors: Robyn S
authors: RS
authors: Hetem
authors: Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg 2193, South Africa.
authors: Andrea
authors: A
authors: Fuller
authors: Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg 2193, South Africa.
authors: Duncan
authors: D
authors: Mitchell
authors: Université de Lyon, Ecologie des Hydrosystèmes Naturels et Anthropisés, CNRS-UMR 5023 Université Lyon 1, 43 Bvd 11 Novembre 1918, F-69622 Villeurbanne Cedex, France.
authors: Jean-Louis
authors: JL
authors: Rouanet
mesh_terms: D000818:Animals; D001481:Basal Metabolism / Q000502:physiology*; D001831:Body Temperature; D002940:Circadian Rhythm; D003080:Cold Temperature; D005260:Female; D008322:Mammals / Q000502:physiology*; D011817:Rabbits; D013696:Temperature
keywords: Biologging; Energy expenditure; Oryctolagus cuniculus; Thermal conductance; Thermogenesis