Ammoniation of oil palm frond (OPF) with non-protein nitrogen (N) sources has been shown to improve the nutritional value and digestibility of OPF in ruminants. This study evaluated the effect of treating OPF without (control) or with different urea levels (1%-5%) on chemical composition and in vitro gas production, digestibility and fermentation properties using goat rumen fluids. The results showed that the treated OPF with urea (1%-5%) had significantly lower (p