It is generally recognized that an application of sodium hydroxide (NaOH) is effective for improving nutritive values of low quality roughages and crop straws in ensiling as feeding stuffs. In the present study, oat whole crop, rice whole crop and rice straws treated with NaOH were subjected to evaluation in regard to their digestibilities in feeding and effects on live-weight gains and blood serum of beef cattle. Under an application of NaOH, the digestibilities of those materials were considerably increased. No significant differences in visual as well as chemical qualities were seen between the silages with and without NaOH-treatment. The blood serum analysis on the animals fed with NaOH-treated silages died not show any functional disorder. Most of the Na consumed by the animals was excreted through urine. The daily live-weight gains of the steers fed with NaOH-treated silages were satisfactory when a small amount of supplementary stuffs such as barley flakes and urea was added. These results suggest that beef production in Japan possibly be developed without heavily relying on imported grains but by applying NaOH to domestically produced feeding stuffs such as oat whole crop, rice whole crop or rice straws in ensiling them.