The objective of this study was to investigate the relationship between the concentrations of the different
ketone bodies in milk and blood and to evaluate these concentrations for the detection of subclinical
ketosis. A total of 60 multiparous cows were used. Concentrations of
acetone,
acetoacetate, and
beta-hydroxybutyrate were analyzed quantitatively in blood and milk, and the Ketolac strip test was used for semiquantitative determination of
beta-hydroxybutyrate in milk. Cows were defined subclinically ketotic when their concentration of blood
beta-hydroxybutyrate was over 1200 micromol/L. High correlation coefficients were observed between blood
acetone and blood
acetoacetate, and between blood and milk
acetone. On the contrary, concentrations of milk and blood
beta-hydroxybutyrate were poorly correlated with the other concentrations of
ketone bodies. The Ketolac strip test overestimated the concentrations of
beta-hydroxybutyrate in milk. For the detection of subclinical
ketosis, the best sensitivity-specificity combination was obtained with the determination of
acetoacetate in blood or milk, with threshold concentrations of 125 and 50 micromol/L, respectively. Determination of
beta-hydroxybutyrate in the milk via an enzymatic analysis or via the Ketolac strip test provided valuable results, with threshold concentrations of 70 and 100 micromol/L, respectively. The simplicity of use of the Ketolac strip test makes it a valuable way to investigate subclinical
ketosis.