Studies have shown that especially butyric acid may have a prominent role in the reduction of invasion [25], and colonization of Salmonella in the caecal microbiota [26]. Butyricimonas was the most dominant genus in caecum samples from conventional cages, but this difference was not reflected in any variations found in the colonization level of S. Enteritidis as reported by De Vylder et al. [19], who found no difference in excretion level and time between cage systems. We did not find evidence that the introduction of S. Enteritidis to the intestinal microbiota

were able to change the species diversity in ileum or caecum. When individual T-RFLP profiles from Salmonella positive layers were compared with cage mates that had cleared the infection no differences were observed. When comparing the distribution of Selleckchem EPZ015938 OTU in each group before and after inoculation, the balance between different classes and genera were also maintained

throughout the study. The low impact on the intestinal microbiota may Vorinostat mw be explained by the fact that Selleckchem CRT0066101 inoculation only induced a subclinical infection, in contrast to experimental studies where a more profound disturbance of the microbiota has been observed in cases where diarrhoea has followed infection [27, 28]. In the early studies of Nurmi and Rantala [29], it was shown that a highly diverse intestinal microbiota in broilers is one of the best barriers towards colonization with Salmonella (competitive exclusion). However, we did not find that decreased diversity in the layers had a significant impact on the colonization and elimination of Salmonella. It is likely that this colonisation resistance is highly important in broilers where a mature flora has not been established yet, but in layers this may not be as important. Furthermore, in the second inoculation study where seeder birds Phosphatidylethanolamine N-methyltransferase were housed together with non-infected birds, De Vylder et al. [18] found that the transmission of S. Enteritidis was higher among hens housed in aviary

or floor system than in conventional and furnished cages. A likely explanation for our observation is that direct contact to faecal material from infected hens is very important for the transmission of S. Enteritidis in a flock, and that the higher species diversity found in layers with more contact with faecal material does not prevent colonization, but keeps it at a relatively low level. Conclusions In the present study, we have compared the intestinal microbiota in layers from different housing systems under experimental conditions. When laying hens were housed in conventional cages, a change was observed in their caecal microbiota towards a less diverse flora, with the most prevalent genera being more dominating compared to aviary and furnished cage.