This study is to evaluate effects on fermentation characteristics and nutrition value of Gac shells with different additives. Gac shells are treated with 2 percent of molasses, 3 percent and 5 percent of cassava meal, 3 percent and 5 percent of maize bran and with 10 percent of taro leaves and stems. Samples are collected to determine the nutrition value for 0, 7, 14, 21, 30 and 60 day periods of ensiling. From the samples, physical characteristics of the silages such as color, presence of fungus and smell are evaluated. Fresh Gac shells showed low content In dry matter (10.59 percent + or - 0.93) and soluble sugar (0.35 percent in DM). After 60 days of being ensiled, the quality of silages is acceptable in terms of odor and appearance in almost treatments, with pH in the range of 3.08 to 3.62. The lowest pH value was found in the treatment with 5 percent maize bran and with 10 percent taro leaves and stems. Lactic acid concentration reached 5.09 percent to 6.26 percent in dry matter (DM) after 60 days. With the increasing ensilage time, dry matter content increased and crude protein decreased in all treatments, but changes were not significant. Gac shell is concluded to be well ensiled with 5 percent of maize bran or 10 percent of taro leaves and stems compared to other treatments.