Silage is the result of fermentation from feed ingredients that have high water content (about 50% -80%) such as corn (Zeamays L), in a vacuum (anaerobic) by lactic acid bacteria. Making silage is one alternative to traditional biotechnology that can be done, especially utilizing the availability of local food sources. The purpose of this study is to determine the ability of lactic acid bacteria isolated from rumen fluid in Bali cattle as a starter in making corn forage silage, and evaluate the quality of corn forage silage provided by lactic acid bacteria isolated from rumen fluid in Bali cattle. The method used in this research is, making probiotics, making samples and testing the quality of silage. The results of this study are, lactic acid bacteria from the rumen contents of Balinese cattle rumen can be used as corn forage silage starter, this is indicated by the silage color in the range of yellowish green to brownish green which indicates that the silage is of good quality, silage aroma in the range of score 2 , 33-2.83 which produces a fresh sour aroma to near fresh-smelling acid, silage pH before being injected with Escherichia coli with an average of 4.51-4.81 which is within the normal range. Corn forage silage given lactic acid bacteria from the rumen contents of Bali cattle showed good quality, this is seen from the final silage results given by pathogenic bacteria Escherichia coli which showed silage color with an average of 1.83-2.58 indicating that the silage color included in the optimal range of brownish green, silage aroma in the range of 1.42-2.75 which gives a fresh sour aroma, silage pH in the range of 4.42-4.58 which indicates silage is in good range, dry silage content ranges from 32.4% -34.4% which is below the normal range, and the average percentage of damage is 0% - 3% which shows the difference in damage presentation between silage given by lactic acid bacteria and control treatment.