The possible relationships between trace elements, oxidative stress and subclinical ketosis during transition period were evaluated in dairy cows. Blood samples were obtained by jugular venipuncture at four times: 3 and 1 week before and 1 and 3 weeks after calving. The highest concentration of MDA and BHB was observed on the week 1 after calving. In contrast, the serum values of copper, zinc, albumin, uric acid and TIBC decreased after calving. After calving, zinc concentration showed a significant negative correlation with MDA concentration (P<0.005). The concentrations of MDA after calving showed a positive correlation with BHB (P<0.005), while zinc showed a negative correlation with BHB at this time (P<0.05). The results of logistic regression test showed that the decreased concentration of zinc in the weeks 1 before and 1 after calving increased the occurrence of subclinical ketosis. Moreover, an increase in MDA concentration at the week 1 after calving increased the risk of subclinical ketosis. The results of the present study showed that cattle with insufficient concentrations of trace elements are prone to oxidative stress and subclinical ketosis and cattle with increased oxidative stress are subclinical ketosis-prone.

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