## 4 Discussion
Beta diversity in this study measured the similarity or dissimilarity of microbial communities between samples of the ileum and ceca, thus making it a useful technique to observe changes within the community composition. Although beta diversity consisting of Bray-Curtis, Jaccard, and Unweighted UniFrac produced significant variations in the ileum and ceca, there was no significant effect among hens within treatment groups with Weighted UniFrac, indicating that distinct phylogenetic groups are possible, but the prevalent abundance of taxonomic groups persists. Lower UniFrac distance indicates a more similar bacterial composition between the samples. The two most dominant bacterial phyla in chickenbelong to Firmicutes and Bacteroidetes [39]. Firmicutes species are associated with the decomposition of polysaccharides and the production of butyrate [40]. Bacteroidetes species degrade complex carbohydrates and synthesize propionate via the succinate pathway. ANCOM accounts for the underlying structure in the data and can be used for comparing the composition of microbiomes in two or more populations [41]. The microbiome compositional diversity did not group the samples at family and species levels according to the diet. The function of the ileum has a major role in water and mineral absorption, with evidence of contributing to starch and fat digestion, and is generally known to harbor a diverse and numerically more significant population of bacteria when compared to the other two intestine segments [42]. The ileum microbiota at times can intermix with the microbiota of the ceca. Within the ileum, at the phyla level, Proteobacteria (Gram-negative) had higher relative abundance followed by Actinobacteria (Gram-positive), both non-spore-forming bacteria. Hens belonging to treatment group 2 (2016 hen on 2016 diet) and treatment group 3 (1940 hen on 1940 diet) had an increased abundance of Proteobacteria, suggesting that genetics had a greater influence on the observed bacteria. In that same respect, similar results were seen in hens belonging to treatment group 1 (2016 hen on 1940 diet) and treatment group 4 (1940 hen on 2016 diet) having an increased abundance in Actinobacteria, suggesting that the influence of diet may have been attributed to the observed presence of bacteria. Actinobacteria have a number of important functions, including the degradation/decomposition of all sorts of organic substances such as cellulose, polysaccharides, protein fats, organic acids, etc. The abundance of Actinobacteria in hens belonging to treatment groups 1 and 4 may be a direct result of the composition of the diets provided to these hens. The findings in this study were similar to the results from research conducted by [14; 15], where the majority of phyla belonged to both Proteobacteria and Actinobacteria of the ileum [37]. At the genera level, hens belonging to treatment groups 1 (2016 hen on 1940 diet) and 4 (1940 hen on 2016 diet) had a dominant abundance of Aeriscordovia. Hens belonging to treatment groups 2 (2016 hen on 2016 diet) and 3 (1940 hen on 1940 diet) had a dominant abundance of Leuconstoc. A complex bacterial community is found in the ceca, primarily due to the longer digestive transit times, making it an important site for the recycling of urea, water regulation, and carbohydrate fermentations, while also contributing to intestinal health and nutrition [43; 44]. The abundance of Firmicutes, the major bacterial phyla observed, was dominated in all treatment groups within the ceca, which is a similar result found in the research conducted by [45]. Proteobacteria and Actinobacteria were the second and third abundant components observed at the phyla level in the ceca, which typically accounts for 2-3% of total microbiota. Despite the variations observed, representatives of the phyla mentioned above are found in the ceca of nearly all adult chickens.