In two year`s investigation from 1985 to 1986, yields, chemical components and nutrient quality of rye and barley silage were evaluated at different stages of growth associated with water content of the herbage. Dry matter yields and nutritive quality of silage were increased as the maturity advanced and it occurred the greatest at stage of soft dough for rye and hard dough for barley, when the plants showed 27.0% to 34.8% of dry matter content. The value of net energy lactation (NEL) and starch equivalents (StE) were 5.09 MJ and 410 StE/㎏ in rye and 5.32 MJ and 456 SfE/㎏ in barley. Quality of silage harvested at early stage of growth, final leaf to blooming, was improved markedly by pre-wilting treatment, especially in the chemical compositon and formation of organic acid. Concentrations of total organic acid was relative less changeable under wilting treatment of the materials. However, the formation of lactic acid was increased as water content of the herbage decreased by 1/2 day or whole day treatment for pre-wilting.