Dietary Deoxynivalenol Contamination and Oral Lipopolysaccharide Challenge Alters the Cecal Microbiota of Broiler Chickens

Abstract

Dietary deoxynivalenol (DON) impairs the intestinal functions and performance in broiler chickens, whereas little is known about the effect of DON on the gastrointestinal microbiota. This study evaluated the impact of graded levels of dietary DON contamination on the cecal bacterial microbiota, their predicted metabolic abilities and short-chain fatty acid (SCFA) profiles in chickens. In using a single oral lipopolysaccharide (LPS) challenge we further assessed whether an additional intestinal stressor would potentiate DON-related effects on the cecal microbiota. Eighty 1-day-old chicks were fed diets with increasing DON concentrations (0, 2.5, 5, and 10 mg DON per kg diet) for 5 weeks and were sampled after half of the chickens received an oral LPS challenge (1 mg LPS/kg bodyweight) 1 day before sampling. The bacterial composition was investigated by Illumina MiSeq sequencing of the V3-5 region of the 16S rRNA gene. DON-feeding decreased (p < 0.05) the cecal species richness (Chao1) and evenness (Shannon) compared to the non-contaminated diet. The phyla Firmicutes and Proteobacteria tended to linearly increase and decrease with increasing DON-concentrations, respectively. Within the Firmicutes, DON decreased the relative abundance of Oscillospira, Clostridiaceae genus, Clostridium, and Ruminococcaceae genus 2 (p < 0.05), whereas it increased Clostridiales genus 2 (p < 0.05). Moreover, increasing DON levels linearly decreased a high-abundance Enterobacteriaceae genus and an Escherichia/Shigella-OTU (p < 0.05). Changes in the bacterial composition and their imputed metagenomic capabilities may be explained by DON-related changes in host physiology and cecal nutrient availability. The oral LPS challenge only decreased the abundance of an unassigned Clostridiales genus 2 (p = 0.03). Increasing dietary concentrations of DON quadratically increased the cecal total SCFA and butyrate concentration (p < 0.05), whereas a DON × LPS interaction indicated that LPS mainly increased cecal total SCFA, butyrate, and acetate concentrations in chickens fed the diets that were not contaminated with DON. The present findings showed that even the lowest level of dietary DON contamination had modulatory effects on chicken's cecal bacterial microbiota composition and diversity, whereas the additional oral challenge with LPS did not potentiate DON effects on the cecal bacterial composition.

Keywords: 16S RNA sequencing; broiler; cecum; deoxynivalenol; lipopolysaccharide; microbiota.

Figure 1

Microbiome composition at phylum level for 16S rRNA sequences in cecal digesta of broiler chickens fed diets with increasing levels of deoxynivalenol (DON; 0, 2.5, 5, or 10 mg DON/ kg diet). Values are presented as least squares means ± standard error of the mean (SEM); n = 20 broilers per feeding group. Presented data include both animals with and without oral lipopolysaccharide challenge (LPS) 1 day prior to slaughter within the respective feeding group. Data were not affected by LPS and DON × LPS (p > 0.10). ^* Linear contrast: p < 0.10.

Figure 2

Shannon index (A), Simpson index (B), and Chao1 richness estimate (C) in cecal digesta of chickens fed diets with increasing levels of deoxynivalenol (DON; 0, 2.5, 5, or 10 mg DON/kg diet). Values are presented as least squares means ± standard error of the mean (SEM); n = 20 broilers per feeding group. Presented data include both animals with and without oral lipopolysaccharide challenge (LPS) 1 day prior to slaughter within the respective feeding group. ^* Contrast comparing the 0 DON with all DON groups (0 vs. DON): p < 0.05. ^** Quadratic contrast: p < 0.05.

Figure 3

Total short chain fatty acids (SCFA), acetate, proprionate, butyrate, isobutyrate, valerate, isovalerate, and caproate concentrations in cecal digesta of chickens fed diets with increasing levels of deoxynivalenol (DON; 0, 2.5, 5, or 10 mg DON/kg diet) and with or without oral lipopolysaccharide challenge (LPS) 1 day prior to slaughter. Values are presented as least squares means ± standard error of the mean (SEM); n = 10 broilers per treatment; n = 9 in the 5 DON+con and 5 DON+lps groups. ^a,b,c DON × LPS interaction: Least squares means of total or individual SCFA with no common superscripts differ significantly between groups; p < 0.05. ^**Quadratic contrast: p < 0.05.

Figure 4

Correlation matrix between short chain fatty acid (SCFA) concentrations and relative abundance of bacterial genera in cecal digesta of chickens fed diets with increasing levels of deoxynivalenol (DON; 0, 2.5, 5, or 10 mg DON/kg diet) and with or without oral lipopolysaccharide challenge (LPS) 1 day prior to slaughter. Colors refer to the degree of correlation.