摘要:The objective of this research was to investigate the effect of Aspergillus oryzae on fermentation of mixture of rumen contents and jackfruit peel on in vitro gas production and digestibility. The method used in this study was an experiment using a randomized block design (RBD) of 4 treatments and 3 replications. The treatments including of T0 = 50% rumen contents + 50% jackfruit peel, T1 = 40 % rumen contents + 60% jackfruit peel + 0,4% Aspergillus oryzae, T2 = 30% rumen contents + 70% jackfruit peel + 0,4% Aspergillus oryzae, T3 = 20% rumen contents + 80% jackfruit peel + 0,4% Aspergillus oryzae. Variables observed were gas production, dry matter digestibility (DMD), and organic matter digestibility (OMD). Data were analyzed by using Analysis of Variance (ANOVA) from Randomized Block Design, if there were significant effect between the treatments then tested with least significant different (LSD). The result showed that fermentation of mixture of rumen contents and jackfruit peel have highly significant effect (P<0.01) on gas production, and significant effect (P<0.05) on DMD and OMD. Gas production, DMD and OMD of fermented mixture of rumen contents and jackfruit peel are higher than control without fermentation. It is concluded that the higher jackfruit peels the higher gas production, DMD and OMD.