Dietary coated essential oil and organic acid mixture supplementation improves health of broilers infected with avian pathogenic Escherichia coli

Abstract

Colibacillosis caused by avian pathogenic Escherichia coli (APEC) is a very prevalent disease in poultry farms in China. The exploration of effective non-antibiotic substances is of great significance for the control of APEC infections. This experiment evaluated the efficacy of coated essential oil and organic acid (EOA) supplementation to prevent E. coli O78 infection in broiler chickens. A total of 288 one-day-old male broiler chicks were randomly distributed into 4 groups with 6 replicates per group. Chickens were fed a diet either supplemented with EOA (500 mg/kg feed) or not, and either uninfected or infected with E. coli O78 intratracheally. Results showed that E. coli O78 infection reduced body weight gain, increased mortality and the ratio of feed to gain along with cecal and liver E. coli load, damaged gut mucosa, induced local and systemic inflammation, and altered cecal microbial composition, diversity and function (P < 0.05). Supplemental EOA improved feed conversion efficiency, lowered gross lesion scores and cecal E. coli population, enhanced intestinal goblet cells and serum IgG concentration, and tended to decrease serum IL-12 production (P < 0.05). Essential oil and organic acid addition downregulated IFN-γ mRNA, tended to decrease mucin-2 mRNA levels while upregulating IL-10 mRNA, and tended to increase ZO-1 gene expression in the jejuna of infected birds at 7 d after E. coli O78 challenge (P < 0.05). The 16S rRNA gene sequencing indicated that both EOA addition and E. coli O78 challenge altered the diversity and composition of the cecal microbiota community. Furthermore, infected birds fed EOA showed decreased Bacteroidetes and genus Lactobacillus abundance compared with the infected control. LEfSe analysis showed that Firmicutes, Ruminococcaceae, Clostridiales, Clostridia, Lactobacillus, Lactobacilaceae, and cc-115 were enriched in the non-infected but EOA-treated group (P < 0.05). Collectively, dietary EOA supplementation could mildly alleviate E. coli-induced gut injury and inflammation.

Keywords: Avian pathogenic Escherichia coli; Broiler chicken; Encapsulated essential oil and organic acid mixture; Health.

Fig. 1

Effect of essential oil and organic acid mixture (EOA) on (A) mortality rate and (B) lesion scores of broiler chickens challenged with Escherichia coli O78. Treatment groups: A = neither infection nor EOA addition control, K = E. coli O78 infection control, B = EOA addition but without infection, L = both EOA addition and E. coli O78 infection.

Fig. 2

The overall description of gut microorganism among the 4 groups. (A) Venn diagram, (B) Chao index, (C) Shannon index, (D) Simpson index, (E) abundance-based coverage estimator (ACE). Treatment groups: A = neither infection nor essential oil and organic acid mixture (EOA) addition control, K = Escherichia coli O78 infection control, B = EOA addition but without infection, L = both EOA addition and E. coli O78 infection.

Fig. 3

Beta diversity analysis of cecal microbial community. (A) Partial least squares discriminant analysis (PLS-DA). (B) Nonmeric multidimensional scaling (NMDS). Treatment groups: A = neither infection nor essential oil and organic acid mixture (EOA) addition control, K = Escherichia coli O78 infection control, B = EOA addition but without infection, L = both EOA addition and E. coli O78 infection.

Fig. 4

Composition of caecal microbiota of the broiler chickens among the 4 groups at phylum level. (A) Relative abundance of top 8 bacterial phyla. (B) Comparison of the relative abundances of the top 5 bacterial phyla among the 4 groups. Treatment groups: A = neither infection nor essential oil and organic acid mixture (EOA) addition control, K = Escherichia coli O78 infection control, B = EOA addition but without infection, L = both EOA addition and E. coli O78 infection.

Fig. 5

Stacked bar chart of cecal microbial structure at the genus level. (A) Relative abundance of top 21 bacterial genera. (B) Comparison of the relative abundances of the bacterial genera which were greater than 1% among the 4 groups. Treatment groups: A = neither infection nor essential oil and organic acid mixture (EOA) addition control, K = Escherichia coli O78 infection control, B = EOA addition but without infection, L = both EOA addition and E. coli O78 infection.

Fig. 6

Differential bacterial taxa in cecal microbiota of the B and K groups using LEfSe analysis (P ≤ 0.05 and LDA cutoff > 2.0) (n = 6/group). (A) Cladogram plot. (B)The histogram shows differentially abundant bacteria in the B and K groups ranked by linear discriminant analysis (LDA) scores. Treatment groups: A = neither infection nor essential oil and organic acid mixture (EOA) addition control, K = Escherichia coli O78 infection control, B = EOA addition but without infection, L = both EOA addition and E. coli O78 infection.

Fig. 7

Predictive functional profiles generated from 16S rRNA marker gene sequences using PICRUSt at KEGG levels 2. (A and B) Differentially regulated metabolic pathways in A vs. K group, K vs. L group, respectively. The corrected P-value is listed at the right. Treatment groups: A = neither infection nor essential oil and organic acid mixture (EOA) addition control, K = Escherichia coli O78 infection control, L = both EOA addition and E.coli O78 infection.

Fig. 7

Predictive functional profiles generated from 16S rRNA marker gene sequences using PICRUSt at KEGG levels 2. (A and B) Differentially regulated metabolic pathways in A vs. K group, K vs. L group, respectively. The corrected P-value is listed at the right. Treatment groups: A = neither infection nor essential oil and organic acid mixture (EOA) addition control, K = Escherichia coli O78 infection control, L = both EOA addition and E.coli O78 infection.