Validation of the Doubly Labeled Water Technique in Small Insectivorous Bats by Comparison with Indirect Calorimetry

Abstract

The doubly labeled water technique (DL W) tor the measurement of free-living energy expenditure was validated by comparison with indirect calorimetry for nine small « 1a g) insectivorous bats (n = 7. Pipistrellus pipistrellus: n = 2. Plecotus auri tus) over a fivefold range of daily metabolism. The DL W estimates were consistentlv greater than the indirect calorimetry estimates. The mean algebraic difference was +9.5% with the Lifson and :YtcClintock equation. +5.1 % with the Coward et al. equa tion. and-+-3..+% with the Schoeller et al. equation. These differences were not siznifi. . = cant SInce the range at errors was large. Mean absolute deviation was 13.5%. 13.7%. and 14.5% for the three respective equations. The assumption of a constant respira tory quotient (RQ) did not introduce significant error. The overestimate of enerzv =, I This work was supported by NERC grant GR3i 5155. We are grateful to Drs. D. M. Bryant and P. Tatner for help in development of the technique in its application to bats and to Dr. A. E. Fallick and T. Donnelly for help in processing samples at the Scot tish Universities Research and Reactor Centre. East Kilbride. We thank A. Masson for technical assis tance and S. Forrest, who typed the manuscript. We are grateful for the helpful comments of Prof. D. A. Schoeller and Drs. D. M. Bryant and P. Tatner on earlier drafts and this paper.

Heart rate as a predictor of metabolic rate in heterothermic bats

“…A study on two small insectivorous bat species showed that a 5-fold range of average energy metabolism measurements could be generated using this method, when bats employed torpor to differing degrees (Speakman and Racey, 1988). Here, we show that regardless of torpor bout length there is a strong correlation between f H and V · O 2 across a complete torpor bout and at rest, consistent with the potential for the f H method to reliably measure field energy expenditure.…”

Male Weasels Decrease Activity and Energy Expenditure in Response to High Ambient Temperatures

“…In the calculations we assumed a fixed evaporation of 25% of the water flux (equation 7.17 [25]). Eighty-nine percent of final blood samples were obtained within three hours of a 24 h interval from the initial blood sample, which controlled for circadian rhythms of activity (max  =  7.2 h from 24 h interval [27], [28]). The average body mass of weasels, based on values obtained at the beginning and end of the DLW technique, was used in all analyses.…”

Limits to sustained energy intake. X. Effects of fur removal on reproductive performance in laboratory mice

“…This method has been previously validated by comparison to indirect calorimetry in a range of small mammals (e.g. Speakman and Racey, 1988a) and provides an accurate measure of DEE over periods of several days (Speakman and Król, 2005b). Dayto-day variability in estimated energy metabolism suggests measurements spanning multiple 24·h periods may give a superior representation of energy metabolism (Speakman et al, 1994;Berteaux et al, 1996).…”