Abstract
The purpose of this experiment is to explore the effects of dietary supplementation of benzoic acid, Enterococcus faecium, and essential oil complex (BEC) on coccidia and Clostridium perfringens challenge in laying hens. A total of 80 Lohmann gray laying hens (35 wk old) were allocated to 4 treatments in a 2 × 2 factorial arrangement with the main effects of Clostridium perfringens type A (CP) and coccidia challenge (with or without challenge) and 2 BEC levels (0 and 1,000 mg/kg). The total experimental period was 6 wk. The results showed that: the challenge group significantly decreased the laying rate and average daily feed intake (ADFI) of laying hens (P(Challenge) < 0.01). The BEC + challenge group significantly increased the laying rate and decreased the feed conversion ratio (FCR) of laying hens (P(BEC) < 0.05). The challenge significantly decreased the thickness, strength, and relative weight of eggshell (P(Challenge) < 0.05). The BCE + challenge group significantly increased the relative weight and strength of the eggshell (P(BEC) < 0.05). The challenge significantly increased the crypt depth of the duodenum, jejunum and ileum, and decreased the villus-to-crypt ratio (V/C) (P(Challenge) < 0.01). The BEC + challenge group decreased the crypt depth of the duodenum and jejunum, and increased the V/C of the duodenum (P(BEC) < 0.01). The pathological scores of duodenum and jejunum of the challenge group were significantly higher than other groups (P(Challenge) < 0.01), while the BEC + challenge group had lower pathological scores of jejunum (P(BEC) < 0.01). The challenge significantly decreased the mRNA expression of Occludin, Mucin-2, Zonula occluden-1 (ZO-1) (P(challenge) < 0.05); whereas the BEC group significantly increased the expression of Occludin, Mucin-2, and Claudin-1 mRNA (P(BEC) < 0.05). The challenge significantly increased the level of interleukin 1β (IL-1β) in the jejunum (P(Challenge) < 0.05). Taken together, adding BEC to the diet can improved production performance and egg quality of layers, by protecting intestinal health against Clostridium perfringens type A (CP) and coccidia challenge.