Quantitative analysis of the intestinal bacterial community in one- to three-week-old commercially reared broiler chickens fed conventional or antibiotic-free vegetable-based diets

Abstract

Aims: To explore the effect of drug-free poultry production on the intestinal microflora of broiler chickens, the bacterial community of this environment was quantitatively profiled in both conventionally reared birds and birds reared without antibiotic growth promotants (AGPs) on a vegetable-based diet. Methods and Results: Quantitative, real-time PCR with group-specific 16S rDNA primer sets was used to enumerate the abundance of the following chicken gastrointestinal (GI) tract phylogenetic groups: the Clostridium leptumFaecalibacterium prausnitzii subgroup (Clostridium genus cluster IV), the Clostridium coccoides -Eubacterium rectale subgroup (Clostridium cluster XIVa and XIVb), the Bacteroides group (including Prevotella and Porphyromonas), Bifidobacterium spp., the Enterobacteriaceae, the Lactobacillus group (including the genera Leuconostoc, Pediococcus, Aerococcus and Weissella), the Clostridium perfringens subgroup (Clostridium cluster I), Enterococcus spp., Veillonella spp., Atopobium spp., Campylobacter spp. and the domain Bacteria. A species-specific 5¢-nuclease (Taqman) assay was also employed to specifically assess Cl. perfringens abundance. Ten birds were sampled from each of two commercial chicken houses, one in which feed was supplemented with AGPs and exogenous animal protein, and the other vegetable-based and drug-free, at 7, 14 and 21 days of age. The ileal community was dominated by two large populations, the lactobacilli and the Enterobacteriaceae, with those taxa much more numerous in drugfree vegetable-based diet fed birds than those conventionally reared at the 7-and 14-day time periods. The progressive changes in microflora in both the conventional and drug-free caeca were similar to each other, with the Enterobacteriaceae sequences dominating at day 7, but being replaced by obligate anaerobe signature sequences by day 14. Of note was the finding that all the day 14 and day 21 replicate caecal samples from the drug-free house were positive for Campylobacter spp. averaging >10 8 16S rDNA gene copies per gram wet weight. Conclusions: Quantitative, real-time PCR indicates that the effects of drug-free rearing on the chicken GI tract microbial community are most pronounced in the ileal region, but AGPs may be important in controlling Campylobacter colonization of the caecum. Significance and Impact of the Study: A quantitative taxonomic understanding of the shifting microbial ecology of the broiler chicken gut microbiota is important in the light of AGP withdrawal. AGP withdrawal has occurred in response to concerns over the transfer of antimicrobial-resistant bacteria to humans via the food production chain.

Exposure of different bacterial inocula to newborn chicken affects gut microbiota development and ileum gene expression

“…The exclusive population of Lactobacillus detected in the ileum of group B on day 1 is most likely because of the impact generated by the bacterial composition of Inoculum-II. The fluctuation in the numbers of Lactobacillus, particularly in the ileum, has been previously reported to be sensitive to the environmental stimuli and strongly influenced by diet components (Lu et al, 2003;Wise and Siragusa, 2007). Whether these conditions are similar to those used in this study needs to be further investigated.…”

Differential antimicrobial peptide gene expression patterns during early chicken embryological development

“…SNPs in AvBD3 and AvBD7 have been previously associated with resistance to Salmonella infection in broiler chickens [55,56] , and the use of genetic markers for resistance to infection would eliminate many of the current limitations in enhancing immune function [57] . Manipulation of AMP expression levels, via maternal diet for example [58,59] may in future be a mechanism to control the selective colonisation of chickens by particular bacteria and thereby exclude zoonotic agents including Salmonella and Campylobacter .…”

Veillonella magna sp. nov., isolated from the jejunal mucosa of a healthy pig, and emended description of Veillonella ratti

“…The species V. parvula, V. atypica, V. dispar, V. montpellierensis, V. denticariosi and V. rogosae have been isolated from man and V. criceti, V. ratti, V. rodentium and V. caviae have been isolated from rodents. In food animals, Veillonella strains are also detected regularly as indigenous inhabitants of all sections of the gastrointestinal tract (Johns, 1951;Alexander & Davies, 1963;Smith & Jones, 1963;Tannock & Smith, 1970;McGillivery & Cranwell, 1992;Leser et al, 2002;Tsukahara & Ushida, 2002;Murphy et al, 2005;Gong et al, 2007;Wise & Siragusa, 2007).…”