Abstract
It is urgent to develop effective antibiotic alternatives for the control of subclinical necrotic enteritis (NE) in chickens after in-feed antibiotics have been banned. The current study investigated the efficacy of drinking water supplemented with essential oils and organic acids mixtures (EOA) on growth performance and intestinal health of broilers challenged with necrotic enteritis (NE). A total of 360 one-day-old Arbor Acres male broilers were randomly divided into 5 treatment groups, including non-challenged control group (T0), challenged NE group (T1), and challenged NE chickens treated with 0.2 % EOA1 (T2) or 0.2 % EOA2 (T3) in drinking water, along with NE-challenged chickens treated with 45 mg/kg bacitracin methylene disalicylate (BMD) in the diet (T4). Results showed that drinking water supplemented with either EOA1 or EOA2 significantly decreased Clostridium perfringens load in ileal content (P < 0.05). EOA2 markedly reduced jejunal crypt depth, serum lipopolysaccharide (LPS) content, ileal IL-1β mRNA level and myeloperoxidase (MPO) activity, significantly increased Mucin-2 mRNA abundance in ileum of NE infected broilers (P < 0.05) when compared with single NE-infected group. The 16S sequencing analysis revealed that, compared with single NE-challenge group and the antibiotic BMD group, the addition of EOA1 in drinking water significantly increased the Shannon index and Simpson index of ileal microbiota in NE-infected broilers (P < 0.05), while drinking water supplemented with either EOA1 or EOA2 significantly decreased Streptococcus relative abundance of NE-infected broilers (P < 0.05). In summary, drinking water with EOA2 might alleviate the intestinal injury induced by NE challenge, and the gut health-improving effects of EOA2 were better than that of EOA1.