Abstract: Background: This study was performed to determine ammonia oxidation ability of the livestock farm waste by a microbial consortium and to reduce the amount of ammonia gas from the manure. Materials and Methods: The study consisted of five treatments: Without the addition of isolates as control, the addition of Pseudomonas sp., LS3K, the addition of Candida sp., LS3T, the addition of Arthrobacter sp., LM1KK and the addition of microbial consortium. The observed parameters consisted of microbial growth and the oxidation ability of the microbial consortium to minimize the concentration of ammonia. The obtained data were analyzed using one-way analysis of variance and the mean differences between treatments were tested by Duncan’s Multiple Range Test (DMRT). Results: The results showed that determined by Optical Density (OD), the microbial consortium was capable of growing with the addition of more than 10% ammonia with a value of maximum growth (μ max) 4.02 h–1. The number of colonies that grew on the addition of 0, 2.50, 5, 7.50 and 10% (NH4)2SO4 were 1.03×105, 0.94×105, 1.60×105, 0.82×105 and 0.86×105 CFU mL–1, respectively. The reduction of the ammonia concentration in the liquid medium with (NH4)2SO4 was 15.37 ppm. Ammonia emission from the chicken excreta, dairy cows feces and beef cattle feces was lower after the treatment with the addition of microbial consortium which was 28.72, 71.47 and 56.50 ppm, respectively compared than that of the control. Conclusion: The result can be concluded that the ability of oxidation by the microbial consortium was the most optimal in the oxidizing ammonia in beef cattle feces. The capability oxidizing of microbial consortium can reduce as much as 15.34 ppm concentration of ammonia in beef cattle feces.