Changes of milk fatty acid composition in four lipid classes as biomarkers for the diagnosis of bovine ketosis using bioanalytical Thin Layer Chromatography and Gas Chromatographic techniques (TLC-GC)

Abstract The aim of this study was to extend the limited research available on the association between the concentration of milk fatty acids and the elevated plasmatic value of β-hydroxybutyrate (BHB) in early lactation of dairy cows. Fifty-four Holstein Friesian dairy cows were enrolled in the study. All animals were classified on the basis of their blood BHB concentration: BHB ≥ 1.0 mmol/L (BHB-1, sick group) and BHB ≤ 0.99 mmol/L (BHB-0, healthy group). Using Thin Layer Chromatography (TLC), four lipid classes (cholesterol esters -CE-, phospholipids -PL-, free fatty acids -FFA- and triacylglycerols -TAG-) were separated, and then the fatty acid (FA) composition was determined by High Resolution Gas Chromatography coupled with Flame Ionization Detector/Mass Spectrometer (HRGC-FID/MS). The FA profiles were used to investigate the diagnostic potential value of milk fatty acids for the correct classification of cows with BHB concentration above the established threshold (BHB