This study evaluated the effects of Nypa fruticans fruit pellet supplementation combined with different CP levels on rumen fermentation characteristics and CH4 production using an in vitro gas production technique. A 3 × 4 factorial arrangement was used, consisting of three CP levels (12, 14, and 16%) and four levels of Nypa fruticans fruit pellet supplementation (0, 0.5, 1.0, and 1.5% of substrate dry matter), with incubation run included as a random effect in the statistical model. Rumen fluid