ABSTRACT. Penelitian bertujuan mengetahui kualitas complete feed dengan level pelepah sawit fermentasi berdasarkan kecernaan bahan kering, bahan organik, produksi N-NH3, produksi volatile fatty acids (VFA) dan produksi biomassa protein mikrobia serta protein total secara in vitro. Materi yang digunakan adalah complete feed tersusun atas konsentrat dan pelepah sawit fermentasi dengan berbagai level yaitu 0, 10, 20 dan 30%. Rancangan percobaan yang digunakan adalah rancangan acak lengkap (RAL) dengan 4 perlakuan complete feed dengan level pelepah sawit fermentasi yang berbeda. Data diolah menggunakan sidik ragam yang dilanjutkan dengan uji beda wilayah berganda Duncan. Hasil penelitian menunjukkan bahwa complete feed dengan level pelepah sawit fermentasi yang berbeda berpengaruh nyata (p0,05) terhadap kecernaan bahan kering dan bahan organik, produksi N-NH3, produksi VFA, dan produksi protein total, sedangkan pada biomassa protein mikrobia tidak terdapat perbedaan yang nyata (p0,05). Rata-rata nilai kecernaan bahan kering pada perlakuan T0, T1, T2 dan T3 adalah 69,59; 71,9; 69,05; dan 62,58%. Rata-rata nilai kecernaan bahan organik pada perlakuan T0, T1, T2 dan T3 adalah 63,59; 63,15; 65,50; 52,66 %. Rata-rata produksi VFA pada perlakuan T0, T1, T2 dan T3 sebesar 105,8; 142,7; 136,4; dan 135,7 mM. Rata-rata produksi NH3, biomassa protein mikrobia dan produksi protein total pada perlakuan T0, T1, T2 dan T3 berturut-turut adalah 6,48mM, 15,04mg/ml;, 34,10mg/g; 7,36mM, 15,75mg/ml, 23,72mg/g; 8,18mM, 12,59mg/ml, 33,72mg/g); dan 6,60mM, 15,31mg/ml, 40,80mg/g. Berdasarkan hasil penelitian disimpulkan bahwa penggunaan pelepah sawit fermentasi dengan level 20% dalam complete feed menghasilkan produksi VFA, kecernaan bahan kering dan bahan organik yang cukup baik sehingga dapat menjadi pakan alternatif sumber serat pengganti rumput. (Digestibility, fermentability and in-vitro production of microbial protein on complete feed based on fermented palm frond) ABSTRAK. This study aimed to determine the quality of a complete feed containing fermented palm fronds based on the digestibility of dry matter, organic matter, N-NH3, VFA, microbial protein biomass, and total protein in vitro. The material used was complete feed composed of concentrates and fermented palm fronds at various levels, i.e., 0, 10, 20, and 30%. The experiment was conducted as a completely randomized design (CRD) with four complete feed treatments containing different levels of fermented palm fronds. The data were processed using analysis of variance, followed by Duncan’s multiple range test. The results demonstrated that the complete feed with different levels of fermented palm fronds had a significant effect (p0.05) on the digestibility of dry matter and organic matter, N-NH3 production, essential fatty acids production, and total protein production, whereas there was no significant difference (p 0.05) on microbial protein biomass. The average dry matter and organic matter digestibility values of T0, T1, T2, and T3 treatments were 69.59; 63.59, 71.9; 63.15, 69.05; 65.50, and 62.58%; 52.66% respectively. The average production of volatile fatty acids of T0, T1, T2, and T3 treatments were 105.8; 142.7; 136.4; and 135.7 mM. respectively, while the average N-NH3 production, microbial protein biomass, and total protein production of the T0, T1, T2, and T3 treatments were 6.48, 7.36, 8.18, 6.60 mM; 15.04, 75, 12.59, 15.31 mg/ml; and 34.10, 23.72, 33.72, 40.80 mg/g. In conclusion, the use of fermented palm fronds at a 20% level in complete feed gave the best result in the production of volatile fatty acids, improved digestibility of dry matter, and organic matter, so it can be used as an alternative feed to replace grass fiber.