**Abstract**

The intestinal microbiota of the chicken plays a central role in enhancing nutrient absorption and affecting both host performance, health and immunity. This study was conducted to assess the relative abundance of bacteria microflora in different segments of the gastrointestinal tract (duodenum, jejunum, ileum, and cecum) of broiler chicken raised in an open-sided house. One hundred fifty-oneday-old chicks of Cobb 500 broiler chickens were raised in an open-sided house fed a standard non-medicated corn-soybean meal diet from day 0–35 days of age. The study showed a distinctive difference in the bacterial community between each region of intestinal segments and the diversity of the bacterial community changed as the chicken aged. In addition, Lactobacillales were the dominant 16S rDNA sequences in the duodenum, jejunum, and ileum libraries, whereas Clostridiales were the dominant 16S rDNA sequences in the cecum libraries. The bacterial microbiota relative abundance differed significantly (*p* < 0.05) across different intestinal segments. In conclusion, each region developed its own bacterial community and the relative abundances of the bacterial community were quite different. Based on the composition of the microbial community, future gut modulation with beneficial bacteria, such as probiotics, may benefit the host.

**Keywords:** broiler chicken, 16S rDNA, intestine, gut microbiota, open-sided house
