The blood of all mice (Se-deficient mice = 20; Se-adequate mice = 20) were collected and then the plasma were separated to measure concentration of MDA, activity of SOD,GSH-Px and CAT at day 0, 2,7,13,19,25 and 28p.i.. A, the concentration of MDA; B, the activity of SOD; C, the activity of GSH-Px; D, the activity of CAT. There were extremely significant difference between the two groups (p<0.01) in activity of SOD, GSH-Px, MDA and CAT at day 0, 2, 7,13,19,25 and 28p.i. However, there were no significant difference (p>0.05) between the two groups in the concentration of MDA at day 0 and 28p.i., extremely significant difference from day 7 to day 28 p.i. (p<0.01). Results are expressed as the mean concentration per group±standard deviation (SD).