Prussic Acid Poisoning
September 7, 2022 | View PDF
Sorghum, sudangrass, and sorghum-sudangrass hybrids are a great warm season forage option. However, these plants contain cyanogenic glycosides that can be converted to hydrocyanic acid (HCN), also known as prussic acid, when the plants are injured by freezing, cutting, or crushing.
Prussic acid can be very toxic to livestock as it interferes with aerobic metabolism, which results in lack of oxygen and ultimately leads to suffocation of the animal. Signs of prussic acid poisoning include difficulty breathing, staggering, muscle spasms, salivation, convulsions, increased heart rate, and collapse. Prussic acid poisoning is fast acting, as clinical signs and even death can occur in a matter of minutes.
Reduce the risk of prussic acid poisoning by not grazing sorghum, sudangrass, or sorghum-sudangrass hybrids until they are 18-24 inches tall. It is also important to wait 7-10 days after a frost before grazing. Harvesting these plants for hay or silage reduces the concentration of prussic acid. However, testing samples prior to feeding is always a good idea.