Reprod. Nutr. Dev. 44 (2004) 17-27
DOI: 10.1051/rnd:2004012

Validation of the measurement of glucose appearance rate with [6,6-²H₂]glucose in lactating dairy cows

Sophie Lemosquet^a, Jean Noël Thibault^b, Agnès Thomas^c, Elisabeth Debras^d and Catherine Hurtaud<sup>a

a</sup>  Unité mixte de Recherches sur la Production du Lait, INRA, 35590 Saint-Gilles, France
^b  Unité mixte de Recherches sur le Veau et le Porc, INRA, 35590 Saint-Gilles, France
^c  Unité de Recherches sur les Ruminants, INRA de Theix-Clermont-Ferrand, 63122 Saint-Genès-Champanelle, France
^d  Unité d'Etude du Métabolisme Azoté, INRA de Theix-Clermont-Ferrand, 63122 Saint-Genès-Champanelle, France

(Received 4 December 2002; accepted 13 November 2003)

Abstract - 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 × 4 and 5 × 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.

Key words: dairy cows / glucose metabolism / GC-MS / [6,6-²H₂]glucose / validation

Corresponding author: Sophie Lemosquet lemosque@st-gilles.rennes.inra.fr

© INRA, EDP Sciences 2004