Influence of Benzoic Acid and Oregano Essential Oil on Intestinal Histomorphology, Lesion Scores, and Tight Junction Gene Expression in Mixed Eimeria -Challenged Broiler Chickens

The study evaluated the efficacy of dietary benzoic acid (BA) and oregano essential oil (OEO) as alternatives to a commercial coccidiostatic drug in broiler chickens challenged with Eimeria spp. A total of 252 one-day-old broiler chicks (Cobb-500™) were randomly assigned to six treatments, each with six replicates (n = 42 per treatment): (i) negative control (NC); (ii) positive control, coccidia-challenged and untreated (PC); (iii) supplemented with salinomycin at 60 mg/kg of feed and challenged (Sal); (iv) BA at 500 mg/kg of feed and challenged (BA); (v) OEO at 500 mg/kg of feed and challenged (OEO); and (vi) BA at 500 mg/kg plus OEO at 500 mg/kg of feed and challenged (B&O). The study demonstrated that supplementation with BA and OEO, either individually or in combination, improved intestinal villus morphology, particularly in the jejunum, and mitigated the adverse effects of Eimeria infection. The combined supplementation of BA and OEO reduced infectivity and faecal scores to levels comparable to those observed with salinomycin treatment. Moreover, the combined treatment ameliorated gut structural damage and restored growth performance to near that of the non-infected control group by 21 days post-infection (DPI). The study demonstrated that combined supplementation with benzoic acid (BA) and oregano essential oil (OEO) reduced Eimeria infectivity and improved faecal scores comparable to salinomycin, while enhancing intestinal integrity, and jejunal morphology. These effects, accompanied by increased expression of Zonula occludens-1 and Claudin-1, support the potential of BA and OEO as natural anticoccidial alternatives in broiler chickens.