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The concept of competitive exclusion is well established in poultry and different products are used to suppress the multiplication of enteric pathogens in the chicken intestinal tract. While the effect has been repeatedly confirmed, the specific principles of competitive exclusion are less clear. The aim of the study was to compare metabolites in the cecal digesta of differently colonized chickens. Metabolites in the cecal contents of chickens treated with a commercial competitive exclusion product or with an experimental product consisting of 23 gut anaerobes or in control untreated chickens were determined by mass spectrometry. Extensive differences in metabolite composition among the digesta of all 3 groups of chickens were recorded. Out of 1,706 detected compounds, 495 and 279 were differently abundant in the chicks treated with a commercial or experimental competitive exclusion product in comparison to the control group, respectively. Soyasaponins, betaine, carnitine, glutamate, tyramine, phenylacetaldehyde, or 3-methyladenine were more abundant in the digesta of control chicks while 4-oxododecanedioic acid, nucleotides, dipeptides, amino acids (except for glutamate), and vitamins were enriched in the digesta of chickens colonized by competitive exclusion products. Metabolites enriched in the digesta of control chicks can be classified as of plant feed origin released in the digesta by degradative activities of the chicken. Some of these molecules disappeared from the digesta of chicks colonized by complex microbiota due to them being metabolized. Instead, nucleotides, amino acids, and vitamins increased in the digesta of colonized chicks as a consequence of the additional digestive potential brought to the cecum by microbiota from competitive exclusion products. It is therefore possible to affect metabolite profiles in the chicken cecum by its colonization with selected bacterial species. [ABSTRACT FROM AUTHOR]

Contaminated chicken meat is a major source of human Campylobacteriosis and rates of infection remain high, despite efforts to limit the colonisation of broiler (meat) chicken flocks on farms. Using conventional testing methods of culture or qPCR, Campylobacter is typically detected amongst broiler flocks from 3 wk of age, leading to the assumption that infection is introduced horizontally into chicken rearing houses at this time. In this study, we use parallel sequencing of a fragment of the Campylobacter outer membrane protein, encoded by the porA gene, to test for presence of Campylobacter DNA amongst fresh fecal samples collected from broiler flocks aged 23 to 28 d. Campylobacter DNA was detected in all of the 290 samples tested using the porA target, and in 48% of samples using 16S bacterial profiling, irrespective of whether or not Campylobacter could be detected using conventional qPCR thresholds. A single porAf2 variant was predominant among flocks that would be determined to be Campylobacter ' positive' by conventional means, but a diverse pattern was seen among flocks that were Campylobacter 'negative'. The ability to routinely detect low levels of Campylobacter amongst broiler flocks at a much earlier age than would conventionally be identified requires a re-examination of how and when biosecurity measures are best applied for live birds. In addition, it may be useful to investigate why single Campylobacter variants proliferate in some broiler flocks and not others. [ABSTRACT FROM AUTHOR]

Chickens in commercial production are hatched in hatcheries without any contact with their parents and colonization of their skin and respiratory tract is therefore dependent on environmental sources only. However, since chickens evolved to be hatched in nests, in this study we evaluated the importance of contact between hens and chicks for the development of chicken skin and tracheal microbiota. Sequencing of PCR amplified V3/V4 variable regions of the 16S rRNA gene showed that contact with adult hens decreased the abundance of E. coli, Proteus mirabilis and Clostridium perfringens both in skin and the trachea, and Acinetobacter johnsonii and Cutibacterium acnes in skin microbiota only. These species were replaced by Lactobacillus gallinarum, Lactobacillus aviarius, Limosilactobacillus reuteri , and Streptococcus pasterianus in the skin and tracheal microbiota of contact chicks. Lactobacilli can be therefore investigated for their probiotic effect in respiratory tract in the future. Skin and respiratory microbiota of contact chickens was also enriched for Phascolarctobacterium, Succinatimonas, Flavonifractor, Blautia , and [ Ruminococcus ] torque though, since these are strict anaerobes from the intestinal tract, it is likely that only DNA from nonviable cells was detected for these taxa. [ABSTRACT FROM AUTHOR]

In this study, we addressed differences in the development of gut microbiota in 4 successive batches of commercially hatched broiler parent chickens. When planning this study, we expected to find a batch with compromised performance which would allow identification of microbiota of suboptimal composition. Microbiota composition was determined only by sequencing the V3/V4 region of 16S rRNA genes in samples collected from chickens 5 to 18 wk of age. In a total, 100 and 160 samples originating from the ileum or cecum were processed, respectively. In one of the flocks with suboptimal performance we identified an increased abundance of Helicobacter brantae forming over 80% of ileal microbiota in individual chickens. Moreover, we also tested samples of 53-wk-old hens from the same genetic line in which egg production decreased. In this case, cecal microbiota was enriched for Fusobacterium mortiferum forming over 30% of total cecal microbiota. Although none of the identified unusual microbiota members have been well recognized as pathogenic, they may represent new opportunistic pathogens of chickens worth of further investigation. Analysis of gut microbiota composition by next generation sequencing thus proved as a useful and unbiased alternative to bacterial culture, especially in the cases of unspecific symptoms like decrease in flock performance. [ABSTRACT FROM AUTHOR]