Abstract
Chemical compositions and in vitro dry matter digestibilities (IVDMD) in straws were compared among twenty four varieties and strains of rice (Oryza sativa L.), consisting of fourteen japonica type rice and ten indica type rice in experiment 1. and each proportion of straw fractions ; leaf blade, leaf sheath and stem, and chemical composition and IVDMD of each fraction were examined on rice straws of four varieties ; Akihikari, Reimei, Habataki and Raikei in experiment 2. The mean culm length was shorter in indica types than japonica types, and acid detergent lignin (ADL) content tended to be higher in japonica types than indica types. There was no apparent difference in the other chemical composition between japonica types and indica types. IVDMD ranged from 37.7% to 52.2%. The mean IVDMD was higher in indica types than japonica types and the difference between two types was about 7%. Crude protein (CP) content had a positive correlation, and culm length, organic matter (OM), acid detergent fiber (ADF) and ADL contents had negative correlations with IVDMD. There was no apparent difference in the proportions of straw fraction. But, the IVDMD of the fraction of Habataki and Raikei were higher than Akichikara and Reimei. These results indicate that differences in IVDMD are mainly dependent on IVDMD of the straw fraction. There were singificant correlations between IVDMD and culm length, OM, CP, ADF and ADL contents of rice straws.
