Abstract Background: Phytogenic additives would be helpful to mitigate the detrimental impact of Campylobacter jejuni (C. jejuni) on broiler chickens. Objective: The experiment aimed to assess the effects of cinnamon, rosemary, and oregano powder on physiological responses of broiler chickens challenged with C. jejuni from 0 to 42 days of age. Methods: A total of 192 one-day-old male broiler chickens were divided into 6 treatment groups. The treatments included: negative control (NC; basal diet without additives and no C. jejuni challenge), positive control (PC; basal diet with C. jejuni challenge), PC with cinnamon, rosemary, or oregano powder (3g/kg each), and PC with Erythromycin (55mg/kg). Except for the NC group, all chicks were orally challenged with 2×108 cfu/mL C. jejuni daily from days 21 to 25. Feed intake (FI), Body weight gain (BWG), feed coversion ratio (FCR), energy efficiency ratio (EER), and protein efficiency ratio (PER) were assessed during the rearing period (0-42 days). On day 42 of age, fresh excreta samples were collected from each pen to determine apparent DM digestibility and excreta microbiota. In addition, at the end of the experiment, blood samples were collected to evaluate blood profile, and liver enzyme activities. Results: C. jejuni challenge (PC treatment) decreased BWG, EER, and PER, while increasing FCR of broiler chickens (p < 0.05), while, rosemary, oregano, and Erythromycin improved these performance parameters akin to NC. PC diet showed negative effect in ileal morphology, alleviated by additives except cinnamon (p < 0.05). Dietary additives successfully reduced Campylobacter levels and increased Lactobacilli counts in the PC. Rosemary and oregano lowered plasma total cholesterol (p < 0.05). Alanine aminotransferase (ALT) elevation by C. jejuni challenge in the PC group was prevented by rosemary, oregano, and Erythromycin (p < 0.05). Conclusions: Oregano and rosemary alleviate the impact of C. jejuni challenge.
