Association between methylated fatty acids and early pregnancy outcomes in dairy cows: a plasma GC‒MS assay

Early conception failure is a major contributor to infertility in dairy cows. Fatty acids (FAs) play critical roles in maintaining normal reproductive function. This study aimed to determine Long Chain Fatty Acids (LCFAs) and their derivatives in plasma and to explore their association with early pregnancy outcome in high producing dairy cows. Blood samples were collected from 36 inseminated cows at 30 days post-insemination (dpi). Pregnancy was diagnosed at both 30 dpi and 45 dpi. Plasma LCFA levels were quantified via gas chromatography-mass spectrometry (GC-MS). Cows that experienced conception failure or early embryonic death (before 45 dpi; n = 25) had significantly higher concentrations (P < 0.05) of oleic acid (OA), palmitic acid (PA), stearic acid (SA), and linoleic acid (LA) than cows carrying viable embryos at 45 dpi (n = 11). Methylated LCFAs were detected only in the plasma of cows with healthy embryos at 45 dpi. The plasma OA: PA and LA: PA ratios exceeded 1 in cows with conception failure. Principal component analysis indicated that a component including LA and methylated FAs differed between cows that failed to conceive from those with viable embryos at 45 dpi. These findings reveal the composition of LCFAs and their derivatives in the cattle plasma and suggest an association between LCFAs and their methylated derivatives with early conception outcomes in dairy cows.