**1. Introduction**

Many studies have used sequencing technologies to characterize the microbial communities that colonies the gastrointestinal tracts of chickens and to characterize the development of these communities over time [1]. It is well known that the chicken gut microbiota influences the host gut development, growth performance, and overall health [2, 3]. Different factors, such as diet and bird age, have a strong influence on the diversity and composition of the intestinal microbiome in chickens, which has grown in complexity and richness as chickens have grown [3, 4]. Each region of the gastrointestinal tract (GIT) develops its own distinct bacterial community, and the structure of the microflora gets more complicated and varies as chickens age, position in the digestive system, feed, breed, and environment change [5–8].

Several studies have shown the beneficial effect of gut microbiota on the physiological, metabolic, immunological, digestion, and nutrient absorption of the host [6]. Evaluation of the bacterial community and intestinal development of different genetic lines of chickens has become a recent point of interest [9]. A greater understanding of the chicken gut function and microbiology will provide a new opportunity for the improvement of broiler chicken health and production raised in an open-sided house.

The use of molecular approaches, which involve examining the structure of bacterial communities by detecting the distinguishing features of microbial DNA isolated from community samples, has solved the problems associated with microbe culture [10, 11]. Using these methods, researchers discovered that 90% of the bacteria in the chicken GIT belong to previously undiscovered species [12]. Furthermore, metagenomics (a nonculture-based technique) was established, allowing researchers to examine microbial communities in various habitats indepth [13]. Metagenomic analysis has provided important information on microbial community alterations and succession [13].

Understanding the taxonomic composition of the bacterial community of the gastrointestinal tract, diversity and succession will permit detecting disruption in the microbiota. This information is crucial, as it may allow for the manipulation of intestinal flora to improve intestinal health and overall bird performance. The objective of this study was to use 16S rDNA-based analysis to analyze the relative abundance, diversity, and changes with age in the microbial community detected in different sections of the gut of broiler chickens.
