Jeniyati Fransiska Mali Pengarang MARTHEN YUNUS Dosen Pembimbing 2 MARKUS MITEN KLEDEN Dosen Pembimbing 1 Marthen Yunus Penguji 1 Markus Miten Kleden Ketua Penguji Edwin J L Lazarus Penguji 2

The aim of this research was to measure the profile of volatile fatty acids and methane gas concentration as the effect of kleinhovia hospitaleaves utilization in complete ration. Method used was experiment method with completely randomized design consist of 4 treatment and 4 replication as research design. The treatments were: R0 = complete ration contain 100% of native grass; R1 = complete ration contain 85% native grass and 15% kleinhovia hospitaleaves; R2 = complete ration contain 70% native grass and 30% kleinhovia hospitaleaves and R3 = complete ration contain 55% native grass and 45% kleinhovia hospitaleaves. Variabel measured was profile of volatile fatty acids i.e. C2, C3 and C4 and methane gas concentration. The result showed that the average of C2, C3 and C4 concentration (mM) of each tretanent was 42.55±3.86;14.16±0.90;1.63±0.09(R0).35.53±4.50;12.32±1.94;1.32±0.34(R1). 37.40±2.30;13.22±0.33; 1.44±0.21 (R2). 27.66±5.13;11.45±0.50;1.25±0.12(R3).While methane gas concentration (mM) was 18.54±1.70 (R0); 15.46±2.17 (R1); 16.11±1.11 (R2); 12.72±0.65 (R3).Statistical analysis showed that the treatment had very high effect(P<0.01)on C2 and methane gas concentration, high effect (P<0.05)on C3 and while no effect (P>0.05) on C4 concentration. It can be concluded that useofkleinhofia hospitaleaves in complete ration resulted in a decrease of VFA profile and methane gas concengtrationwith the best level is the treatment R3. Key words:complete ration, bafkenu leaves, native grass, volatile fatty acids, methane