CONCENTRATIONS OF CITRATE AND KETONE BODIES IN COW´S RAW MILK
The milk composition of high-yielding dairy cows is highly related to their nutrition. The energy deficiency in dairy cows can cause subclinical or clinical ketosis. In ketotic state the concentration of ketone bodies (acetone, AC; acetoacetic acid, ACAC; and β-hydroxybutyric acid, BOHB) increases in the different body fluids and simultaneously, changes in concentration of other compounds are also expected. The authors´ hypothesis is that the members of the TCA-cycle, such as citric acid (CA) also change in association of increased formation of ketone body. To support this hypothesis the concentrations of ketone body components and CA were parallel measured and their relationship was studied in raw milk samples. Based on the AC concentration of the milk samples two groups were formed retrospectively: High Acetone (HA) Group (n=41) of AC concentration >0.4mM and Low Acetone (LA) Group (n=78) with the AC level ≤ 0.4 mM. In all samples very low ACAC level was found, which is a consequence of the spontaneous decarboxylation of ACAC to AC during the usual sample storage. Focusing on the results of HA Group the authors found significant relationship between CA and ketone bodies and a parallel drop of AC and CA during the metabolically crucial first 1-4 weeks of lactation. For this reason they suggest to introduce simple, easy, automated methods to determine AC and/or CA concentration in raw milk.