This research aimed to study the effect of inoculums dosages of the Pleurotus ostreatus fungus fermented toAzolla on NDF (Neutral Detergent Fiber), ADF (Acid Detergent Fiber), cellulose and lignin of Azolla. The research wasdone in the Laboratory ofAnimal Science Faculty,University of Jambi and Animal Science Faculty, University ofAndalas. The materials used were Azolla powder which were dried (± 12% moisture), Pleurotus ostreatus fungus, andthe others materials which were needed in analysis of NDF, ADF, cellulose and lignin. Parameters were dry matter, crudefiber, crude protein, NDF, ADF, Cellulose and Lignin content. The design used in this research was CompletelyRandomized Design (CRD) with 4 treatments and 5 replications. The inoculums dosages were 0% (P0), 3% (P1), 6%(P2) and 9% (P3). The result of this research showed that the treatments were significantly decreased (P0,05). In conclusion, the inoculums dosage of 6% of Pleurotus ostreatusfungus toward fermented to Azolla (A. microphylia) significantly decreased of NDF, ADF, cellulose and lignin but itwas not differ with inoculums dosages of 9%
