2021 | Volume 37 | Special Issue 1 | Page 136 Sarhad Journal of Agriculture Introduction A gricultural waste is an alternative source of fber for ruminants, specifcally in the dry season, which is also cheap and has a high ability. Rice straw (Oryza sativa L.) is potential waste that Indonesian people have not widely used, but only a small portion of rice straw was utilized as an energy source for ruminants. Rice straw is a low-quality feed and limited utilization due to low protein (3.47 %) and the highest lignin (6.70 %) (Prihartini et al., 2009). He et al. (2019) also reported that the chemical composition of rice straw is dry matter 28.2 %, crude protein 8.16 %, true protein 6.65 %, nonprotein nitrogen 1.52 %, neutral detergent fber 62.6 %, acid detergent fber 33.5 %, and water-soluble Abstract | Tis study aimed to determine the efect of supplementation lignolitic probiotics in rice straw (Oryza sativa L.) on digestibility and efciency of microbial protein synthesis using in vitro residual gas production and the optimal lignolitic probiotic in rice straw. Te materials used were rice straw IR 64 cultivar and lignolitic TPG probiotic. Te method used was Randomized Complete Block Design (RCBD) with four levels of treatments and three groups. In addition, a further test was conducted using Duncan’s multiple range due to a signifcant diference. Te treatments were rice straw added by probiotic level which consisted of (P0: 0 %; P1: 0.5 %; P2: 1.0 %; P3: 1.5 %). Also, the in-vitro gas production was observed at 2 h, 4 h, 8 h, 16 h, 24 h, 36 h, 48 h, 72 h, and 96 h incubation period for digestibility and efciency of microbial protein synthesis using the in-vitro method. Te result showed that treatment signifcantly afected (P < 0.05) gas production, digestibility, and efciency of microbial protein synthesis (ESPM). Te highest gas production, dry matter (DM), organic matter (OM) digestibility, and ESPM were 73.86 mL 500 mg –1 DM; 43.56 %; 48.41 %, and 34.26 g N kg –1 FOM (fermented organic matter) at 96 h incubation respectively. Terefore, probiotic lignolitic improves the digestibility of rice straw lignocelluse. Indah Prihartini 1 *, Miftachi Ari 2 , Manar Fayiz Mousa Atoum 3,4 , Akhis Soleh Ismail 1 and Listiari Hendraningsih 1 1 Faculty of Agriculture and Animal Science, University of Muhammadiyah Malang, Jl. Raya Tlogomas 246 Malang 65144, Indonesia; 2 Faculty of Animal Science, University of Brawijaya Malang, Jl. Veteran Malang 65145, Indonesia; 3 Molecular Biology and Genetics, Te Hashemite University, Zarqa PO Box 330127, 13133, Jordan; 4 Faculty of Applied Health Sciences, Te Hashemite University, Jordan. Received | August 19, 2021; Accepted | December 15, 2021; Published | December 30, 2021 *Correspondence | Indah Prihartini, Faculty of Agriculture and Animal Science, University of Muhammadiyah Malang, Jl. Raya Tlogomas 246 Malang 65144, Indonesia; Email: indahprihartini@gmail.com Citation | Prihartini, I., M. Ari, M.F.M. Atoum, A.S. Ismail and L. Hendraningsih. 2021. Te efect of supplementation lignolitic probiotic in rice straw for digestibility and efciency of microbial protein synthesis using in-vitro residual gas production. Sarhad Journal of Agriculture, 37(Special issue 1): 136-143. DOI | https://dx.doi.org/10.17582/journal.sja/2021.37.s1.136.143 Keywords | Improve ruminant feed, Lignocelluse, Lignochloritic bacteria, Rumen microbe, Waste as feed Te Efect of Supplementation Lignolitic Probiotic in Rice Straw for Digestibility and Efciency of Microbial Protein Synthesis using In Vitro Residual Gas Production Special Issue: Agricultural Productivity and Sustainability Improvement in Tropical Region