The effects of difference of growth stage and canopy structure on grazing behavior and intake of hydrogen cyanide potential (HCNp) during the early grazing period were determined on Sorghum pasture under different growth stage (before heading : BH and after heading : AH). The growth stage was flag-leaf stage on BH pasture and first heading stage on AH pasture, respectively. The canopy height was 166.3cm on BH pasture and 191.7cm on AH pasture, respectively. It was clarified that grazing animals intake up to the top of canopy from the position of about 60% of the plant height from the base regardless of the plant height. HCNp intake for a few hours after putting animals on AH pasture showed a tendency to increase as compared with BH pasture. The vertical distribution of HCNp showed a different tendency with growing stage and HCNp in strata located at 60-70% of plant height from the ground level remarkably increased in first heading stage. It indicated that the HCNp contents and their vertical distribution in the canopy structure of Sorghum pasture influenced on intake of HCNp by grazing animal. The heading stage of Sorghum showing high productivity and nutritive value is an adaptive growing stage for grazing utilization in Sorghum pasture. Therefore, it should be investigated details of the changes of HCNp contents during heading stage for restricting the increase of HCNp ratio in herbage intake.

To develop a simple pasture establishment in a wasted mulberry plantation, the effect of seeding rate and the size of bare area on the establishment of pasture plants were examined. Nine experimental plots (6m×6m each) was set in a mulberry plantation (0.44ha) under cattle grazing (178-186 animal unit·day/ha), and three treatments (3.7, 5.6 and 7.4g/m² of seeding rate) were allocated by Latin-square design. Seed mixture of orchardgrass, perennial ryegrass, Kentucky blue grass and white clover (15 : 15 : 5 : 2w/w) was sown by hand on 18 September, 2007. Coverage of plants and bare area size were recorded on 19 September 2007, 16 November 2007, 21 May 2008 and 21 May 2009. The coverage of total sown species tended to increase with increasing of seeding rate in November 2007 (one-way ANOVA, P < 0.1), but the tendency was not observed in 2008-2009 because of dominance of perennial ryegrass and white clover in all treatments. Multiple regression analysis showed a significant effect of bare area size on the coverage of perennial ryegrass and total sown species (P < 0.05) in 2008-2009. The results suggest that surface-sowing under cattle grazing is practical method to establish pasture plants in wasted mulberry plantations.