Rice straw contains less lignin than other straws but has a higher silica content. The leaves contain more silica than the stems (Van Soest, 2006). It is, therefore, recommended to cut rice straw as short as possible to increase the proportion of stems (Göhl, 1982; Van Soest, 2006). Silicas are cell-wall bound or soluble. They are excreted in the urine and some calculi may occur but this does not appear to be a serious problem.
Rice straw contains high levels of oxalates (1-2% DM), which are known to decrease the Ca concentration, making Ca supplementation necessary (Van Soest, 2006; Jackson, 1979).