Effect of oregano essential oils and probiotics supplementation on growth performance, immunity, antioxidant status, intestinal microbiota, and gene expression in broilers experimentally infected with Eimeria

•Supplementation of oregano oil and probiotics improved broiler performance challenged by Eimeria.•A mixture of oregano oil and probiotics supported the immune-oxidant status.•Adding oregano oil with probiotics increased gene expression of MUC2 and CAT-1. The poultry industry has several disease challenges; coccidiosis is considered one of the most dangerous parasitic diseases. Six-hundred Ross 308 male broiler chicks (average initial body weight 41.5 g) were allocated to six groups: negative control uninfected (NCO); positive control infected with Eimeria (PCO); or positive control supplemented with diclazuril (0.2 g/kg diet, DIC); two-strains probiotic (2 g/ kg diet, PRO); oregano essential oil (300 mg/ kg diet, OEO); a combination of 2 g probiotic and 300 mg oregano essential oil (POE). At day 15, all groups except NCO were inoculated via oral gavage with oocysts of mixed Eimeria spp. Our results indicated that the infected chickens with mixed Eimeria (PCO) exhibited lower growth performance, higher mortality rate, and increased oocyst shedding (P< 0.05), in addition to deterioration of immune-oxidative status in broilers on 35 d. On the contrary, Eimeria-infected chickens fed on a diet supplemented with DIC, PRO, OEO, and POE showed improved growth performance (P< 0.05) and decreased mortality and oocyst shedding. Moreover, feeding chickens on POE enhanced body weight gain, feed conversion ratio, crude protein digestibility, and dressing. Furthermore, POE supplements supported immunity and antioxidant status by increasing IgA, IgG, IL-10, and SOD levels (P< 0.05) and reducing IL-6 and MDA levels. Additionally, adding POE altered the gut microbiota structure via an increasing Lactobacillus count and decreasing C. perfringens, E. coli, and Coliforms count. Notably, POE supplements also reduced oocyst shedding and lesion scores. Moreover, the up-regulated nutrient transporters, including the expressions of cationic amino acid transporter-1 (CAT-1) and mucin-2 (MUC-2) were up-regulated (P < 0.05) in the POE group compared to other groups. Therefore, our study concluded that a combination of probiotics and oregano essential oils was preferred as an effective choice for protecting broilers against coccidiosis.