By Andi Anderson
As fall temperatures begin to drop, forage producers should pay close attention to frost conditions, especially when growing sorghum species. Frost can create serious livestock safety concerns because plants in the sorghum family may produce prussic acid, a toxic compound that can cause poisoning in animals.
Prussic acid, also known as cyanide, develops naturally in sorghum plants when plant tissues are damaged. Frost injury is one of the most common causes of this problem. When freezing temperatures damage leaves and stems, plant cells break apart and release compounds that can quickly form toxic levels of prussic acid.
The risk is highest in forage crops such as sorghum, sudangrass, sorghum-sudangrass hybrids, and other related species. Pastures and hayfields can also become risky when they contain significant amounts of sorghum-family weeds, including Johnsongrass and shattercane. Animals grazing these plants shortly after a frost may consume harmful levels of cyanide.
Young plant growth generally contains higher concentrations of prussic acid than mature plants. New shoots that emerge following a frost can be especially dangerous because they often accumulate elevated toxin levels. As a result, livestock should be kept away from affected fields until the risk declines.
Farmers should closely monitor weather forecasts during the fall season. After a non-killing frost, sorghum plants may survive and continue growing, increasing the likelihood of dangerous regrowth. Waiting before grazing or harvesting these fields can help reduce the chance of animal exposure. Following recommended management practices is essential for livestock safety.
Harvesting and storing forage correctly can also help lower risks. In many situations, the prussic acid content decreases over time as forage dries or ferments. Properly cured hay and well-managed silage generally present a lower threat than freshly frosted forage. However, producers should still exercise caution and evaluate forage quality before feeding it to animals.
Livestock poisoning from prussic acid can occur rapidly and may lead to severe health problems or death. Warning signs can include difficulty breathing, weakness, excessive salivation, and sudden collapse. Immediate veterinary assistance is critical if poisoning is suspected.
Fall frosts are a normal part of the growing season, but they require careful forage management. By understanding the risks associated with sorghum species, Johnsongrass, and shattercane, producers can make informed decisions that protect livestock, maintain forage value, and reduce the likelihood of costly losses during the cooler months.
Photo Credit: gettyimages-ahavelaar
Categories: Ohio, Livestock