Asian Journal of Animal Sciences1819-1878xxxx-xxxxxAsian Network for Scientific Information10.3923/ajas.2017.82.87PertiwiningrumAmbarSusilowatiEndangRochijanAgus FitriyantoNanungSoehermanYudistiraFahmi HabibiMochammad22017112Objective: The study aims to determine the effects of rumen fluid addition on biogas formation rate, methane concentration in biogas and coliform content in the sludge from the biogas formation process. Methodology: In this experiment, biogas is produced from the slurry of cow’s manure with the addition of a certain amount of rumen fluid. The amount of additional rumen fluid is varied in four treatments, which is 0, 20, 30 and 40% of the total volume of slurry. The ratio between livestock manure and water is 1:2 with total volume of 450 mL of slurry. The bio-digester are operated in the batch system under anaerobic condition. The observation is conducted for 30 days. Daily measurements of gas productions are recorded, whereas the methane concentration in biogas is measured on day 14, 20, 25 and 30 using the Gas Chromatography (GC). Results: The results showed that rumen fluid addition significantly shortens the time required for the initial phase of decomposition (hydrolysis and acidogenesis) prior to methane formation phase. With rumen fluid addition, the peak in biogas production is achieved on 20 days, while on the control sample (without rumen fluid addition) the peak is achieved later, on 30 days. Taking into account the value of methane concentration, rumen fluid addition is highly recommended since it can give maximum methane concentration (38.20% of the volume) on 20 days, which is 10 days earlier compared to the control sample (22.86% of the volume). Conclusion: It can be concluded that the addition of cow’s rumen fluid as a starter can accelerate the biogas formation process in a shorter time which is 10 days and gives a positive effect on methane formation and methane concentration, compared to the treatment without rumen fluid addition.]]>Bakhov, Z.K., K.U. Korazbekova and K.M. Lakhanova,2014Bond, T. and M.R. Templeton,2011Malakahmad, A., A.B.N. Ezlin and M.Z. Shahrom,2011Karellas, S., I. Boukis and G. Kontopoulos,2010Begum, S. and M.F.M. Saad,2013Gissen, C., T. Prade, E. Kreuger, I.A. Nges and H. Rosenqvist et al.,2014Regassa, T.H. and C.S. Wortmann,2014Malakahmad, A., M. Z.Z.B.C.M. Nasir, S.R.M. Kutty and M.H. Isa,2010Weiland, P.,2010Qasaimeh, A., M.R. Abdallah/Qasaimeh and F.B. Hani,2016Kalia, A.K. and S.P. Singh,2001Kaparaju, P., I. Buendia, L. Ellegaard and I. Angelidaki,2008Saidu, M., A. Yuzir, M.R. Salim, S. Azman and N. Abdullah,2013Jha, A.K., J. He, J. Li and G. Zheng,2010Li, J., A.K. Jha, J. He, Q. Ban S. Chang and P. Wang,2011Jha, A.K., J. Li, Q. Ban, L. Zhang and B. Zhao,2012Montero, B., J.L. Garcia-Morales, D. Sales and R. Solera,2008Yuli, A.H., E. Harlia and E.T. Marlina,2010Surono, I.S.,2004