Resveratrol as a botanical feed additive for the prevention and treatment of Eimeria tenella infection in chicks

Coccidiosis causes substantial losses in poultry production, a challenge further exacerbated by the rising resistance to anticoccidial drugs. Eimeria tenella is recognized as the most pathogenic species; however, effective alternative interventions remain scarce. Resveratrol, a natural polyphenol, exerts antioxidant, anti-inflammatory, and immunomodulatory effects in livestock and poultry; however, its efficacy against E. tenella infection in chicks remains insufficiently characterized. This study evaluated the anticoccidial efficacy of resveratrol in both in vitro and in vivo models. In vitro, the inhibitory effects of resveratrol at varying concentrations on the sporulation of freshly isolated, unsporulated E. tenella oocysts were evaluated. In vivo, 180 chicks were randomly allocated to uninfected and infected control groups, a diclazuril-treated group, and resveratrol-treated groups (200, 400, and 600 mg/kg), and subsequently challenged with 2.0 × 10⁴ sporulated oocysts on day 14. Assessments included growth performance, lesion scores, oocyst count per gram, the anticoccidial index, histopathological evaluation, serum biochemical parameters, oxidative stress markers, and cecal gene expression. Resveratrol inhibited E. tenella oocyst sporulation in vitro in a dose-dependent manner. Resveratrol supplementation improved body weight gain, reduced lesion severity and oocyst output, enhanced antioxidant enzyme activities, upregulated tight junction-associated gene expression, suppressed pro-inflammatory cytokine expression, and mitigated cecal tissue damage. The 400 mg/kg resveratrol group exhibited the most pronounced therapeutic efficacy. In conclusion, resveratrol demonstrated prophylactic and therapeutic efficacy against E. tenella-induced pathology in chicks, supporting its potential as a botanical feed additive for preventing and controlling avian coccidiosis.