GARY STRICKLAND, CHRIS RICHARDS, HAILIN ZHANG, D.L. STEP
It was discovered in the early 1900s that under certain conditions, sorghum is capable of releasing hydrocyanic acid (HCN or prussic acid), which makes them potentially dangerous for grazing. In the plant, HCN is attached to a larger molecule, a cyanogenic glucoside called dhurrin. Dhurrin itself is harmless, as it is simply a compound consisting of a sugar and a non-sugar molecule. However, a two-step enzymatic process results in two hydrolysis products with the final one being HCN. Generally, for this process to occur the plant has to be damaged as the glucosides and degradative enzymes are compartmentally separated within the plant cells. This damage may occur through the chewing action of an animal, a hard freeze where plant cell walls are ruptured, or through mechanical action such as that caused by a swather and its crimpers.