The following Arg × infection interaction was noted for the activity of AST and SOD in the blood of turkeys (both P < 0.001): C. perfringens infection increased the activity of the above enzymes at the lowest and medium Arg content (Arg90 and Arg100, respectively), but not at the highest Arg content (Arg110). This evidence concerns the gene SOD1 and infection due to clostridium perfringens.