Evaluation of variability and classification in sorghum (Sorghum bicolor Moench) and sudangrass (Sorghum sudanense (Piper) Stapf) varieties in regard to feed composition

Forty-seven commercial varieties of sorghum (Sorghum bicolor Moench) and 8 commercial varieties of sudangrass (Sorghum sudanense (Piper) Stapf) were investigated to determine variability in feed composition and growth characteristics, as conventionally grouped in Japan to the five types of varieties including grain (G), dual purpose- (D), sorgo- (S), sorghum-sudangrass hybrid-type (SS) and sudangrass (SG). As 7 variables of crude protein (CP), organic cellular contents (OCC), neutral detergent fiber (NDF), acid detergent lignin (ADL), nitrogen cell wall free extracts (NCWFE), in vitro dry matter degradability (DMD) and in vitro cell wall degradability (CWD), were analyzed by the principal component analysis, the 1st and 2nd principal component were proportion of cellular contents to fiber elements and constituents of cellular contents, respectively. The cumulative proportion of these two principal components accounted for 82% of the variation. Four types of the G, D, SS and SG in sorghum and sudangrass were shown individually to have the high similarity of reed composition, while that of the S type widely varied. As the S type of sorghum was semi-divided into 3 groups including molasses- (M), normal- (N) and extremely late maturing-type (L), their characterization of both feed composition and growth was much more certain. The DMD of sorghum varieties wig significantly inversely related to NDF content and acid detergent fiber (ADF) content (r = -0.98, P0.00l, both), the nutritive value suggesting the order of G nearly equal D M N SS L. The higher CWD of the SG compared with those of sorghum varieties, although the SG had higher NDF content than the sorghum, might also indicate the heterogeneity of the SG from the other sorghum varieties examined. It was concluded in the present study that the classification of varieties of sorghum and sudangrass into 7 types was informative for their cultivation and utilization in the farm