Study 1 aimed to determine the effects of the different inclusions of benzoic acid and essential oil compounds (BA-EOC) as an antibiotic growth promoter replacement in terms of growth performance, and on reducing the fecal E. coli and coliform counts on broilers. A total of 24 birds were divided into 4 groups and randomly assigned to one of four treatments following a Completely Randomized Design. Treatments include basal diet (NC), NC + 400 ppm Avilamycin (PC), NC + 150 ppm BA-EOC, and NC + 300 ppm BA-EOC. Results showed no differences between all treatments in terms of growth performance. However, 150 and 300 ppm BA-EOC exhibited potential to replace the positive control (400 ppm Avilamycin) as a feed additive in reducing E. coli and coliform counts. Study 2 aimed to determine the influence of Allium cepa extract on cecal bacterial diversity using isolated 16S rDNA. Treatments include basal diet (NC), NC + 5ppm Avilamycin (PC), NC + 2.5 mL, NC + 5 ml, NC + 10 mL, and PC + 5 mL of onion extract/L water. Consequently, through Denaturing Gradient Gel Electrophoresis (DGGE), broilers given 2.5mL, 5mL and 10mL onion extract per liter of drinking water have affirmative impact on cecal bacterial diversity.