This study aimed to observe the effect of encapsulated cyanide-degrading bacteria (ECDB) supplementation on in vitro fermentation with bitter cassava leaf meal-based ration. The coating materials for encapsulation consist of alginate, starch, canola oil, and lecithin. The cyanide-degrading (CDB) bacteria strains include Sharpea azabuensis, Bovine rumen bacterium, and Lachnospiraceae bacterium. The treatments were P0 = control ration (Napier grass: bitter cassava leaf meal:concentrate=30:30:40), P1 = P0 + ECDB (0-day storage), P2 = P0 + ECDB (7-day storage), P3 = P0 + ECDB (21-day storage), P4 = P0 + ECDB (28-day storage). Variables observed include pH value, NH3 concentration, dry matter digestibility (DMD) and organic matter digestibility (OMD), volatile fatty acid (VFA) concentration and its proportion, methane estimation, and rumen microbial population. The data obtained were tested using analysis of variance (ANOVA), and if there was any significant difference among treatments were further tested using the Duncan Multiple Range test. The results showed that the addition of encapsulated cyanide-degrading bacteria (ECBD) with different storage times increased (p<0.05) rumen pH, total bacterial population, and NH3 concentrations. On the other hand, DMD, OMD, VFA, protozoa populations, and methane estimation were treated similarly. In conclusion, the addition of encapsulated cyanide-degrading bacteria (ECBD) stored for up to 28 days at room temperature has a beneficial effect on the bacterial population and feed protein degradation.