title: Validation of the DLW method in Japanese quail at different water fluxes using laser and IRMS.
abstract: In Japanese quail (Coturnix c. japonica; n = 9), the doubly labeled water (DLW) method ((2)H, (18)O) for estimation of CO(2) production (l/day) was validated. To evaluate its sensitivity to water efflux levels (r(H(2))O(e); g/day) and to assumptions of fractional evaporative water loss (x; dimensionless), animals were repeatedly fed a dry pellet diet (average r(H(2))O(e) 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 r(H(2))O(e), calculated CO(2) 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 r(H(2))O(e), 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 r(H(2))O(e), 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.
authors.affiliation: Centrum voor IsotopenOnderzoek, University of Groningen, 9747 AG Groningen, The Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Van Trigt
authors.forename: E R T
authors.initials: ER
authors.lastname: Kerstel
authors.forename: R E M
authors.initials: RE
authors.lastname: Neubert
authors.forename: H A J
authors.initials: HA
authors.lastname: Meijer
authors.forename: M
authors.initials: M
authors.lastname: McLean
authors.forename: G H
authors.initials: GH
authors.lastname: Visser
mesh_terms: D000821:Animal Feed; D000818:Animals; D001835:Body Weight; D002245:Carbon Dioxide / Q000378:metabolism; D003370:Coturnix; D003903:Deuterium; D004734:Energy Metabolism / Q000502:physiology*; D007201:Indicator Dilution Techniques; D007834:Lasers; D008297:Male; D013058:Mass Spectrometry / Q000379:methods* / Q000592:standards; D010103:Oxygen Isotopes; D013055:Spectrophotometry, Infrared / Q000379:methods* / Q000592:standards; D014867:Water / Q000378:metabolism*
chemical_list: D010103:Oxygen Isotopes; D014867:Water; D002245:Carbon Dioxide; D003903:Deuterium