Abstract
Equations for predicting total digestible nutrients (TDN) of forage rice (Oryza sativa L.) silage were developed, using data from 17 samples (7 cultivars and 1 line in different growth stages and years). The cultivars and the line used were "Hoshiaoba", "Kusanohoshi", "Supurice", "Nishiaoba", "Saikai-shi 253", "Hinohikari", "Karinomai" and "Kusutamamochi". TDN concentration ranged from 40.6 to 55.1%, and was linearly related to in vitro dry matter digestibility (IVDMD) (r=0.851, P<0.001) and crude ash concentration (CA) (r=-0.782, P<0.001), when a data set from a lodged sample was excluded. A multiple regression equation incorporating the 2 variables showed a high predictive ability : TDN(%DM)=0.329×IVDMD(%)-0.688×CA(%DM)+44.5(R^2=0.815, P<0.001). TDN concentration increased as dry weight percentage of panicle in the sample (PP) increased, showing a relationship of TDN (%DM)=0.324×PP(%DM)+39.3(R^2=0.673, P<0.001), when immature or lodged samples were excluded. The results show that TDN concentration of forage rice silage can be approximately predicted from PP as a farm practice, and more accurately from IVDMD and CA as a laboratory technique, without a digestion trial using animals.
