Roughage feeds were produced from Hyun-aspen (Populus alba $ imes$ p. glandulosa) by steaming-defibration and steaming-explosion. The objectives of this work were to find proper conditions for the treatment of Hyun-aspen by analyzing the compositional change and digestibility and to investigate the change of physical properties of exploded woods. The results of this work were as follows; 1. The method of steaming-de fibration gave the best producing rate of feedstuffs when the chips were steamed (9kg/$cm^2$ under the pressure) for 10 minutes. The yield and the digestibility of feedstuffs were 84.2% and 38.1%, respectively. It is the merit of this method that feedstuffs manufactured by this method was uniformity in particle size, and facilities of fiberboard factory could be used directly, 2. For defibration of the chip by explosion, the proper condition was steamed under the pressure (20kg/$cm^2$) for 4 minutes. The yield and the digestibility of feedstuffs were 93.4% and 68.1%, respectively. The feedstuffs produced under these conditions had higher nutritional quality than rice straw and this method was considered as the best for making feedstuffs from Hyun-aspen chip. But it is defect that exploded feedstuffs was ununiformity in particle size and had unique odor. The physical properties of the feedstuffs were investigated by a light microscope and a TEM. The feedstuffs produced under the low pressure (20 kg/$cm^2$) still maintained the structure of fibers. However, the feedstuffs produced under the high pressure (28 kg/$cm^2$) resulted in higher de fib ration than these prepared under the low pressure. The highly defibrated feedstuffs recombined with solublized lignin. The crystallinity of feedstuffs was increased by 10% and micelle width increased double after treatment.