Dr. Dan Undersander, Forage Agronomist
Sorghum and sorghum-sudangrasses crosses may be poisonous if grazed or fed improperly. The danger of prussic acid poisoning is greatest for forage sorghum varieties, less for sorghum-sudangrass crosses, and least for surdangrasses.
The young, dark green growth or regrowth (less than 18 to 24 inches) the most dangerous stage. Shortly after frost, prussic acid release potential increases slightly. However, they can be safely grazed a few weeks after freezing if there is no substantial regrowth.
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