Abstract: This study was designed to research the effects on serum trace elements of Holstein cows with subclinical ketosis.40 Holstein cows with subclinical ketosis in 1 to 15 d postpartum, through the application of atomic absorption spectrometry, we measured Cu, Fe, Mn, Zn, Se, Co contents in serum, determined GSH-Px, T-AOC, T-SOD activities and MDA content in serum by using spectrophotometer and colorimetric.Cu, Zn, Se, Co contents in serum of positive group were extremely significantly lower than that of control group in the whole testing process (P＜0.01)；Mn concentrations in serum of positive group in the 1st, 5th days detection were significantly lower than the control group (P＜0.05), 10th, 15th day were extremely significantly lower than the control group (P＜0.01)；Fe contents in serum of positive group and control group were not significantly different (P＞0.05), GSH-Px, T-SOD, T-AOC activities in serum of positive group were extremely significantly lower than the control group (P＜0.01),MDA content in serum of positive group was extremely significantly higher than the control group (P＜0.01).Subclinical ketosis had direct impact on GSH-Px, T-AOC, T-SOD activities of cows antioxidant system, indirect effect on serum trace elements Cu, Mn, Se, Zn contents；vitamin B₁₂ had the influence on Co content in serum，so Co content in serum significantly decreased in subclinical ketosis cow；the liver and oxidases of subclinical ketosis cow were damaged, resulting in the Fe content in serum had no significant changes.

Key words:

Holstein cows; subclinical ketosis; trace elements