Correlation of whole blood concentrations of acetoacetate, beta-hydroxybutyrate, glucose and milk yield in dairy cows as studied under field conditions.

The whole blood concentrations of acetoacetate (AA concn), β-hydroxybutyrate (BHB concn) and glucose (gluc concn) of 662 Ayrshire and Friesian dairy cows were measured and their milk yield during the indoor-housing period was recorded. Simple correlations among these parameters were evaluated. The correlation between the AA concn and the BHB concn (r = 0.869) was statistically highly significant (P < 0.001), as were the correlations of the logarithmic value of the AA concn with the gluc concn (r = —0.471) and with the milk yield (r = 0.259), and the correlation between the BHB concn and the glue concn (r = —0.288). The milk yield was found also to be associated with the BHB concn and the glue concn (P< 0.001). The associations between each pair of blood parameters were highly significant, too (P < 0.001). The AA concn was taken to be at least as good an indicator of the energy status of dairy cows as the BHB concn and the gluc concn. The AA concn is not diet-derived like the BHB concn and not as stress-sensitive as the blood concentration of free fatty acids and its diurnal variation is not as wide as the BHB concn and the gluc concn in subclinically ketotic cows. Thus the AA concn may be used as a proxy of the energy status and the ketotic stage of dairy cows under field conditions.