This experiment was carried out to determine the digestible nutrients in alkali treated barley straw-manure silage and to assess the growth performance of yearling cattle, when wild grass hay was partly substituted with straw-manure silage for 6 months. The results obtained are as follows : 1) For digestibility, DCP and TDN value of wild grass hay were 0.32% and 28.99%, respectively, while barley straw-manure silage contained DCP of 14.39% and 62.58 for TDN. 2 ) Six native bull calves, weighing average 110㎏, were used for the feeding trial. Average daily gain for the wild grass fed was 0.27㎏, compared with 0.49㎏ for the silage group. This was 81% increase in weight gain for the silage fed over the grass hay fed. The feed efficiency was 14.78 for the grass hay fed, compared with 8.61 for the silage fed The efficiency improvement of the silage fed was 40% over the grass hay fed.