Abstract
The aspect of ruminal degradation with scanning electron micrograph for the botanical fractions (leaf blade, leaf sheath and internode) of straws from three rice varieties (AK: Akitakomachi, KH: Koganehikari, AH: Akihikari) was examined by incubating the straw samples in the rumen of sheep and related to rumen degradation characteristics including washing loss (WL), 48h dry matter loss (48h-DML), potential degradability and rate of degradation. There were no large differences in proportions of botanical fractions between varieties. The 48h-DML and rates of degradation were significantly varied among the varieties, while the WL and potential maximum degradability were not significantly variable. The intenode and leaf blade had significantly higher values of WL, 48h-DML and potential maximum degradability than the leaf sheath, and the degradation rate of the three botanical fractions was almost same. In the aspect of ruminal degradation with scanning electron micrographs, distinct differences in the degradation of tissue cell walls were observed both between varieties and between botanical fractions, showing that rumen microbial degradation of the AK variety and the internode or leaf blade was higher than the other rice vareities and leaf sheath, respectively. These aspects were coincided with the results of the 48h-DML described above.
