It is generally recognized that inoculants (lactic acid bacteria: LAB) can be used as silage additives to improve the fermentation quality and to enhance animal performance. Especially in Japan, silage-making is a major technique to produce stored feeds and the amount of silage produced in recent years has accounted for about 70% of the amount of roughages produced in farms. Nevertheless in the Japanese environment, commercial inoculants are not always suitable for silage-making. In the present paper, at first, basic aspects of silage-making will be described in Sections 1, 2 and 3, and the problems associated with silage-making for cattle in Japan will be indicated in Sections 4 and 5. For the screening of LAB strains to develop inoculants suitable for silage-making in Japan, the construction of a model system for silage fermentation involving a solid mixed culture consisting of LAB, clostridia and coliform bacteria, referred to as “pouch method”, will be presented in Section 6, and the results of screening of LAB by using the pouch method in Japan and in Thailand will be introduced in Section 7. In Section 8, attempts to improve LAB strains isolated through screening by the cell fusion method and electroporation method will be discussed. Finally, aerobic spoilage of silage which is another major problem will be outlined in Section 9.