With a purpose of finding out the effects of cattle slurry application on thc nutrient contents of herbages and energy productivity in grassland, a field experiment was conducted with two times and five levels of cattle slurry application. The experimental field was designed in a split-plot with threc replications, and lasted from September, 1986 to October, 1990 at the Livestock Experiment Station in Suweon, The results obtained are summarized as follows: 1. The net energy(NEL, StE and TDN) contents of grasses in the plots with cattle slurry application just after cutting were slightly higher when compared to manuring 15 days after cutting. but DCP content has reverse trend. 2. Average net energy(NEL. StE and TDN) and DCP production of the plot with cattle slurry application 15 days after cutting were insignificantly increased by 26 % than those of manuring just after cutting. The energy and DCP yields in the plot with cattle slurry and with slurry + mineral fertilizer were decreased by 21 -27 % and 8- 11 %, respectively than those of the plot with single dressing of mineral fertilizer. 3. Mineral contents of grasses were not significant difference among the treatments of cattle slurry. but considering nutrient balance of animals, application of cattle slurry of 30-$60m^3$/ha with mineral fertilizer was profitable as compared to the other treatments.