As fall begins, livestock producers should remember that the increasing chance of frost raises the risk some forages have of causing cyanide poisoning in ruminants. Specialists with the University of Kentucky College of Agriculture warn that warm-season annual forages, such as sudangrass, johnsongrass, sorghum and sorghum-sudangrass hybrids, have the potential to cause cyanide poisoning, especially when grazed by ruminants at an early growth stage or immediately after a non-killing frost. The greatest risk is frosted Johnsongrass. A non-killing frost can occur when temperatures are around 40 degrees and usually affects valleys and low-lying areas first. Wait until plants have died down after frost before grazing.

“These summer annual forages are high-yielding and high-quality forages, said Ray Smith, UK extension forage specialist. “The potential for toxicity problems is low when these forages are properly managed.”  poisoning should not be confused with nitrate poisoning. Drought and heat can cause nitrate levels in forages to rise, especially in the lower third of the plant. In a year like we are experiencing, being knowledgeable of this disorder will help us not make a bad situation worse. Download the full publication here.