Abstract
Assesments of palatability (measured as mean % herbage consumed by sheep) were made at 7 grazing times on 11 orchardgrass varieties. At the same time, some chemical components were analysed at each grazing time. Chemical component percentages of each variety were compared with the mean of 11 varieties. Then the relationship between chemical components and palatability were examined. Total soluble carbohydrate (TSC) percentage was high in "Hera" and "Pennlate", and low in "S143" and "S345" at almost all grazing times. Crude protein (CP) percentage of "Chinook" increased gradually from spring till fall. Contrarily, that of "S143" and "S345" decreased. Crude fiber (CF) percentages were generally high in "S345" and low in "Pennlate". CF percentage of "S143" increased gradually till fall and that of "Chinook" decreased. Though the varietal variation of in vitro digestibility (IVD) was small, the difference between the highest "Hera" and the lowest "S143" was 4.4% when these varieties were compared using the mean of 7 grazing times. Correlation coefficents between palatability and some chemical components were getting higher after the 5th grazing (middle August). Significant positive relationships were obtained in a combination of TSC and of IVD and palatability. Significant negative correlations were obtained in a combination of CF. However, satisfactory correlations were not established in a combination of CP. Multiple correlations palatability were calculated in a combination of two components among TSC, CP and CF. As a result, the combination of TSC and CF is expected to be the best predicition of palatability for orchardgrass varieties.
