Before challenge, the MDLP group exhibited an up-regulated expression (P < 0.05) of occludin and zonula occluden 1 (ZO-1), whereas the LDLP group showed only an increased expression (P < 0.05) of occludin, with respect to those in the CONT group. At 24 h after ETEC challenge, the expression of all the TJ-associated proteins was down-regulated, and the ETEC group achieved lower claudin-1 and occludin levels than those in the CONT group (P < 0.05). However, the difference among the CONT, LDLP, and MDLP groups was not significant (P > 0.05). At 144 h after challenge, the expression of claudin-1 and occludin in all groups was not significant (P > 0.05). The expression of ZO-1 in ETEC and HDLP groups was down-regulated (P < 0.05) compared to CONT group (Figure 5).