An Arg × infection interaction was noted for the expression of the GLP2 gene in the ileum (P = 0.045): C. perfringens infection increased the expression of the GLP2 gene at the lowest dietary Arg content (90% Lys), but not at the medium or highest Arg content (100% and 110% Lys, respectively) (Table 3). This evidence concerns the gene GCG and infection.