Immediately after sacrifice of experimental piglets, the distal ileal segments containing Peyer’s patches, that were macro- scopically evident, were obtained from approximately 5 cm before the ileocecal valve of each slaughtered piglet (total number of samples = 48). Peyer’s patches have been sampled because they are thought to play a role in the induction of the mucosal immune response (Burkey et al., 2009). The mucosal part of ileal wall that contained Peyer’s patches was gently separated from the remaining ileal wall. Approximately 10 mg of ileal mucosa containing Peyer’s patches were sampled, immediately stored in 1.5 mL cryovials with 0.9 mL of RNAlater solution (Invitrogen, Life Technologies Ltd., Paisley, UK) and frozen at −80◦C. Subsequently, the levels of interleukin (IL)-1