CATTLE PRODUCERS beware! Grazing your cattle on certain pasture grasses after a frost could be deadly for your herd.

John Jennings, a livestock forage specialist for the University of Arkansas Cooperative Extension Service, said, “Prussic acid can develop in johnsongrass, sorghum, sudan and sorghum-sudan crosses such as greengraze and haygraze after the forages wilt from dry weather or after a frost.

“Producers need to be aware of the danger of grazing these crops in the fall. Plants damaged by a frost are the most dangerous. We're having early frosts, so the risk of prussic acid poisoning is very high.”

Jennings said the stressed plants form cyanide compounds commonly called prussic acid. “The compound prevents blood from releasing oxygen from the lungs to tissue. In effect, the animal suffocates.”

Prussic acid is quick-acting and generally fatal, according to Jennings.

He said even if you recognize the symptoms — nervousness, difficulty breathing and staggering — death often occurs before a veterinarian can reach the animal.

“The best way to avoid problems is not to graze cattle on new regrowth or plants that have wilted during dry weather or after a frost,” said Jennings. “If there's a light frost, wait a few days to graze until the plants have freshened up and look normal again. Do not graze plants with leaves that are discolored or blackened from frost damage.”

Jennings said if there's a hard frost, wait until plants are brown and dry. “Prussic acid will dissipate out of the plant as it dries out. If you wait until the forage is dry, it can be safely cut for hay. The hay is safe as long as it's cured properly.”