Fig. 2

Mean optical density of the occludin protein in cecum determined by immunohistochemistry. A MOD = IOD/Area. MOD, mean optical density; IOD, integrated optical density, which is the cumulative optical density in positively stained areas. The area in the formula MOD = IOD/Area refers to the mucosal layer pixel area. mRNA levels of cytokines in cecal tissue. At 7 dpi, the mRNA levels of IL-1β (B), IL-6 (C), IL-4 (D), and IFN-γ (E) in the cecal tissues of chickens (n = 3) in each group were quantified by qRT‒PCR. GAPDH was used as a reference gene. The data are expressed as the means ± SDs (n = 3). *, P < 0.05; **, P < 0.01; ***, P < 0.001; ns, no significant difference. Effects of eugenol essential oil on serum MDA, SOD, CAT, and GSH-Px concentrations in broilers. Note: (F): Serum MDA activity in each group; (G): Serum SOD level in each group; (H): Serum CAT activity in each group; (I): Serum GSH-Px level in each group. *, P < 0.05; **, P < 0.01; *** P < 0.001; ns, no significant difference. HD, high dose of eugenol essential oil; MD, medium dose of eugenol essential oil; LD, low dose of eugenol essential oil; HC, healthy control group (nontreated and noninfected); DC, decoxyquinate treatment control; IC, infected control group (untreated and infected with E. tenella)