Emulsified essential oil-organic acid mixtures in drinking water reduce Salmonella Typhimurium infection and improve intestinal health in broilers

Dietary supplementation with essential oil-organic acid mixtures (EOA) has been reported to effectively control Salmonella infection. However, it has been shown that the antibacterial efficacy of EOA is closely related to processing technology, addition level as well as delivery route. The current study compared the preventive efficacy of adding emulsified EOA (EOA1) and non-emulsified EOA (EOA2) to broiler drinking water separately on Salmonella Typhimurium (ST)-infected broiler chickens. A total of 384 one-day-old Arbor Acres male broilers were randomly divided into 4 treatment groups, including the non-infected control group (A), the positive infection group (B) infected with ST, and ST-infected broilers treated with 0.2 % EOA1 (C) or 0.2 % EOA2 (D) in drinking water. Results showed that adding either EOA1 or EOA2 to drinking water significantly improved feed conversion ratio (FCR) in the earlier and the whole phases (P < 0.05); greatly blocked Salmonella colonization and invasion (P < 0.05); notably up-regulated the mRNA expression of Occludin, ZO-1, Mucin-2 and FABP-2 in the ileum (P < 0.05) of the infected broilers compared with the single ST-infected broilers. Moreover, supplementation of EOA1 in drinking water also notably (P < 0.05) increased ileal villus height (VH) and the ratio of VH to CD along with Butyricicoccus relative abundance in the cecum, but significantly (P < 0.05) reduced crypt depth (CD), TLR-4 mRNA expression level in the ileum as well as Salmonella infection signaling pathway (P < 0.05) in the cecum. In conclusion, drinking water supplemented with emulsified EOA was more effective than non-emulsified EOA in controlling Salmonella infection and improving gut health in broilers.