Validation of the measurement of glucose appearance rate with [6,6-2H2]glucose in lactating dairy cows.
The aim of this study was to validate the measurement of glucose appearance rate using [6,6-2H2]glucose i.v. infusion in lactating dairy cows. Sample enrichments were analysed by gas chromatography/mass spectrometry. Linearity (enriched solutions) and specificity (enriched plasma) were good: for enrichments ranging between 1.6 and 6.3 mol% excess, the slopes were about 1 and the ordinates at the origin were not different from zero. For a plasma enriched at 3.74 mol% excess, repeatability and long term intralaboratory reproducibility coefficients of variation were 1.31 and 1.90%, respectively. The appearance rates were calculated by two models. The values provided by the steady-state model were not different from those provided by the non-steady-state Steele model. Both models can be used because the treatment effects were similarly discriminated regardless of the model. In our experiments analysing the nutritional effects on Ra in mid-lactating cows, the precision of the method (1.90%) was not the limiting factor to detect a significant difference in Ra compared to the statistical precision obtained with the experimental scheme (4 x 4 and 5 x 5 Latin square design). We conclude that in lactating dairy cows, the measurement of glucose fluxes with this method is relevant and minimally invasive for the animals.
Lemosquet
Sophie
S
Unité mixte de Recherches sur la Production du Lait, INRA, 35590 Saint-Gilles, France. lemosque@st-gilles.rennes.inra.fr
Thibault
Jean Noël
JN
Thomas
Agnès
A
Debras
Elisabeth
E
Hurtaud
Catherine
C
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D002417:Cattle / Q000378:metabolism / Q000502:physiology*; D003903:Deuterium; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry / Q000662:veterinary; D005947:Glucose / Q000493:pharmacokinetics*; D007262:Infusions, Intravenous / Q000662:veterinary; D007774:Lactation / Q000378:metabolism*; D008954:Models, Biological; D011897:Random Allocation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D001786:Blood Glucose; D003903:Deuterium; D005947:Glucose