A pilot study to determine the relationship between bacterial populations in the cloaca and the caecum of broiler chickens

The study of animal digestive tracts reveals important information on the host’s health status. For livestock, being able to predict the effect of different treatments on the gut microbiome has important implications for increased sustainability, enhanced animal welfare and increased food safety. However, gut contents can be investigated only after the slaughter of the animal, but cloaca/rectal samples may be collected from live animals and reduce the number of animals killed for experimental purposes. The aim of this study is comparing the microbial communities of caecum and cloaca associated with eight poultry broiler flocks from two English farms. 16S amplicon libraries were run on a MiSeq with a 250 bp PE read metric. The data were evaluated with in qiime1 and qiime2. Comparisons of bacterial communities of cecum and cloaca revealed they are significantly different in terms of the number and types of bacterial species, as well as their abundance (P-value Indicator species analysis of cecum samples showed the class Bacilli were enriched, while Clostridia had greater prevalence in cloaca. Finally, no pathogenic bacterial species of poultry were identified in the analysed animals. Despite the fact sampling cloaca content could be a method to reduce cost and suffering for research purposes, this study reveals the limit of the use of cloacal microbiomes to provide a window into poultry alimentary canal microbiomes.