Use caution feeding cattle Johnsongrass

Johnsongrass is a type of grass that can be found in many local hay fields. Many of these hay fields are temporary grazed by cattle during the late summer time period, which is a good management option if there is not enough to warrant a hay cutting.

Like other members of the Sorghum family, Johnsongrass is a good forage crop, but it can have its problems. Hay and livestock producers need to be aware of the problem associated with Johnsongrass that has been killed by frost and how they can avoid poisoning their animals as they utilize this grass.

For the majority of the growing season, it can be grazed by livestock or cut for hay without any problems, but under certain conditions it can have high amounts of prussic acid. High levels of prussic acid can be toxic to livestock. Sorghums and related forage species readily accumulate these compounds. Foliage that is killed by frost leads to the production of this toxic compound.

The most common problems with prussic acid occur immediately following the first frost in the fall. To be totally safe, avoid grazing or haying all members of the Sorghum family (Johnsongrass, Sorghum, Sudangrass, sudex, etc.) after a frost or hard freeze. Of course, on most livestock operations this is not always practical.

You can greatly reduce your risk by avoiding grazing or haying Johnsongrass for two to three weeks after a killing frost or hard freeze. If you mow Johnsongrass for hay after it is killed by frost, store it for at least a month before feeding it.

This is usually a good way to avoid prussic acid poisoning because this compound is volatile and it will dissipate in time. In fact, prussic acid poisoning is rarely a problem in wellcured hay, particularly when it has been stored for more than one month.

For more details about prussic acid poisoning in livestock, call the Walker County Extension Office at 706-6382548.

Norman Edwards is coordinator of Walker County Extension Service.