The infection of C. perfringens increased the concentration of MDA (P < 0.01), decreased the activity of CAT (P < 0.01), and had a downward tendency on the activity of SOD (0.05 < P < 0.10) in jejunal mucosa of broilers, whereas adding EA to diet declined the concentration of MDA (P < 0.01), while heightened the activities of SOD and CAT (P < 0.01). Here, SOD1 is linked to infection.