Changes in Dry Matter Yield, Nutritive Value and Hydrogen Cyanide Potential (HCNp) with Maturity in a Range of Sorghum Varieties

Abstract

Changes in dry matter (DM) yield , in vitro DM digestibility (IVDMD), crude protein (CP) and hydrogen cyanide potential (HCNp) were investigated with growth stages in four different varieties of Sorghum (cv. Sanjaku sorgo (Gs), High sugar sorgo (Fs), BMR sweet (Bs) and Rich sudan (Ss)), in addition with topdressing effects on these yield and quality. Basal fertilizer was applied at 100 kg N/ha in non-topdressing (NT) plot, in addition with top-dressed at 50 kg N/ha in the 6th leaf stage in topdressing (T) plot. Plants were harvested every 2 weeks after germination (WAG). DM yield, IVDMD, digestible DM yield, CP and HCNp at 12 WAG were ranged in 8.9-15.6 t/ha, 40.0-56.4%, 4.1-8.0 t/ha, 3.9-5.0% and 11.0-30.4 ppm, respectively. Digestible DM yields increased up to 12 WAG in Gs and Fs, while they remained at the same level after 8 WAG in Bs and Ss. HCNp level decreased with maturity to reach the safe level for animal feeding after 4-6 WAG when plant height approached 1 m. Topdressing showed a tendency to increase in DM yield through four varieties. However, the harvest should retard to three weeks after topdressing to secure the safe level of HCNp.