This research aims to analyze the effect of supplementation oil rich in monounsaturated fatty acids and polyunsaturated fatty acids on rumen fermentability in vitro. A total of 49 studies with a total of 278 data were analyzed using a regression analysis mathematical model with IBM SPSS software version 20. The results showed a significant effect (P<0,05) on the decrease in acetate and acetate:propionate ratio in the supplementation of oil rich in monounsaturated fatty acids; dry matter digestibility, total VFA, acetate, and protozoa population on supplementation of oil rich in polyunsaturated fatty acids; and had a very significant effect (P<0,01) on decreasing organic matter digestibility, acetate:propionate ratio, and methane gas production on supplementation of oil rich in polyunsaturated fatty acids. The results of the analysis also showed that there was a very significant effect (P<0,01) on the increase in pH and propionate on supplementation of oil rich in monounsaturated fatty acids, as well as the bacterial population on supplementation of oil rich in polyunsaturated fatty acids. It can be concluded that supplementation of oil rich in polyunsaturated fatty acids has a greater effect on rumen fermentability in vitro.