Abstract: An experiment was conducted to improve the nutrient content of rice bran which supplemented with Zn, Sulfur and urea through fermentation by using cellulolytic bacteria (Bacillus amyloliquefaciens) as inoculums. The objective of this experiment was to study the effect of supplementation of catalytic substrate consisting of Zn, sulfur and urea on the substrata characteristics and its microbial population.The experiment was determination of the optimum conditions (dosage of Zn, Sulfur and urea) for rice bran fermentation based on nutrient quality and quantity of these fermented products. The study was conducted in experimental methods, using the completely randomize design in factorial with 3 treatments were : 1) A factor (Dose of urea: A1 = 1.0%, A2 = 1.5%, A3 = 2.0%), 2) B factor (Dose sulfur: B1 = 0.2%, B2 = 0.4%, B3 = 0.8%) and 3) C factor (Dose Zn: C1 = 0.0025%, C2 = 0.005%, C3 = 0.0075%). Results of study showed that optimum conditions of the fermentation of rice brand was at 2% urea, 0.0025% Zn and 0.2% sulfur. The protein level increased 100% and the mineral content 60%, accompanied by 8.2% of increase in the digestibility. The level of phytic acid decreased 97%. This conditions can increase 36% of metabolizable energy, 15% nitrogen retention, 98% crude fiber digestible.