Abstract | The study aimed to assess the optimal level of supplementation of seaweed Gracilaria sp. in sheep feed on total gas, methane gas, methanogen and protozoa populations, digestibility of dry matter and organic matter. The research material used was rumen fluid from 3 sheep. The treatment tested was supplementation of seaweed flour Gracilaria sp. with a level of 0% (P0), 2% (P1), 4% (P2), 6% (P3) and 8% (P4) based on feed DM which was composed of forage Cynodon dactylon (60%) and concentrate (40%). The study design used a completely randomized design, each treatment was repeated 4 times. The variables measured are total gas, methane gas, methanogen population, protozoa population, dry matter and organic matter digestibility. The results showed that the supplementation of Gracilaria sp seaweed decreased (P <0.05) total gas, methane gas, methanogen population, protozoa population and increased (P<0.05) digestibility of dry matter and organic matter. Conclusions, seaweed supplementation up to the level of 3.6% (DM) effective inhibited the level of methanogenesis giving varying influences. |