Vol. 93, Issue 6, 2147-2154, December 2002
Validation of the DLW method in Japanese quail at different
water fluxes using laser and IRMS
R.
Van Trigt1,
E. R. T.
Kerstel1,
R. E. M.
Neubert1,
H. A. J.
Meijer1,
M.
McLean2, and
G. H.
Visser1,2
1 Centrum voor IsotopenOnderzoek, University of
Groningen, 9747 AG Groningen; and 2 Zoological
Laboratory, 9750 AA Haren, The Netherlands
In Japanese quail (Coturnix c.
japonica; n = 9), the doubly labeled water (DLW)
method (2H, 18O) for estimation of
CO2 production (l/day) was validated. To evaluate
its sensitivity to water efflux levels
(rH2Oe; g/day) and to assumptions of fractional evaporative water loss (x; dimensionless), animals were repeatedly fed a dry pellet
diet (average rH2Oe
of 34.8 g/day) or a wet mash diet (95.8 g/day). We simultaneously
compared the novel infrared laser spectrometry (LS) with isotope ratio
mass spectrometry. At low
rH2Oe, calculated
CO2 production rate exhibited little sensitivity to
assumptions concerning x, with the best fit being found at
0.51, and only little error was made employing an x value of
0.25. In contrast, at high
rH2Oe, sensitivities were much higher with the best fit at x = 0.32. Conclusions derived from isotope ratio mass spectrometry and LS were similar, proving the usefulness of LS. Within a threefold range of
rH2Oe, little error
in the DLW method is made when assuming one single x value
of 0.25 (recommended by Speakman JR, Doubly Labelled Water.
Theory and Practice. London: Chapman & Hall, 1997), indicating its
robustness in comparative studies.
isotope ratio mass spectrometry; laser spectrometry; doubly labeled
water; energy expenditure; water flux
