摘要:Objective: An in vitro study was conducted to evaluate the effect of soybean oil calcium soap (SOCS) and cashew fruit flour (CFF) supplementation on fermentability characteristics, microbial population and nutrient digestibility using rumen fluid of Bali cattle. Materials and Methods: The experiment was arranged in a complete randomized block design with 4 different ration treatments and 3 replicates. The ration treatments were R1: 40% native grass+60% concentrate, R2: 40% NG+60% C, containing 5% soybean oil and calcium soap, R3: 40% NG+60% concentration (C), containing 5% SOCS+10% CFF and R4: 40% NG+60% C, containing 5% SOCS+20% CFF. The measured variables were pH, NH3-N, total volatile fatty acid s and total gas production (fermentability characteristics), total bacteria and protozoa (microbial populations), dry matter and organic matter digestibility. The data were analyzed using one-way analysis of variance and differences between treatments were examined using the Duncans multiple range test. Results: The results showed that the treatments significantly decreased (p<0.05) ammonia (NH3-N) concentration and total volatile fatty acid s production. The different feed treatments did not have any significant effect on pH, total bacteria, protozoa population, dry matter and organic matter digestibility. Conclusion: Supplementation of 5% SOCS in R2 and 5% SOCS+10% CFF in R3 treatments has better NH3-N concentration, total VFA and total gas production compared to the other treatments.