摘要：The research was conducted to study the effect of crude enzyme from cow rumen fluid on nutrient quality of cassava substrates through hydrolysis method. Completely randomized design （CRD） in this research consisted of 4 materials from cassava with its 11 combinations （the total was 15 treatments） with 3 replications. The fifteen treatments were tuber （T）, leaves （L）, peel （P）, onggok （O）, tuber ＋ leaves （TL）, peel ＋ tuber （PT）, tuber ＋ onggok （TO）, leaves ＋ peel （LP）, peel ＋ onggok （PO）, onggok ＋ leaves （OL）, leaves ＋ tuber ＋ peel （LTP）, leaves ＋ tuber ＋ onggok （LTO）, peel ＋ leaves ＋ onggok （PLO）, peel ＋ tuber ＋ onggok （PTO）, peel ＋ leaves ＋ tuber ＋ onggok （PLTO）. Rumen fluid was centrifuged at 10,000 rpm for 15 minutes in 4 ~C. Supernatant was reacted with ammonium sulphate （60%） and incubated in the freezer at 4 ~C for 24 hours. The ground cassava was added by rumen fluid crude enzyme at the dosage of 1% （b/v）. The cassava substrates were kept for 24 hours in room temperature. The addition of rumen fluid enzyme on cassava did not significantly affect dry matter losses （0.96%-2.08%）, but it significantly decreased crude fiber （8.61%-17.83%）. And On the other hand, it increased total sugar （15.19%-29.52%）. The conclusion of this research was that the addition of rumen fluid enzyme on cassava substrates was able to decrease crude fiber （17.83%） and the best total soluble sugar was in tuber （29.52%）, but for dry matter, it was similar to control in the range of 0.96%-2.08%.