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OSU Extension

College of Food, Agricultural, and Environmental Sciences

October 31, 2017 - 8:00am -- Anonymous

As we begin to experience frosts that always generates questions about certain forages and the risk for prussic acid poisoning.  That risk is for warm season forages in the sorghum family because those species contain compounds called cyanogenic glucosides that convert quickly to prussic acid (hydrogen cyanide) in freeze-damaged plant tissue.  Specifically, livestock should not be allowed to graze grain or forage sorghum, sorghum-sudangrass hybrids, or sudangrass varieties or Johnson grass after a frost event.  After a non-killing frost event, do not graze for two weeks and after a killing frost event do not graze until 5-7 days have passed.

Mark Sulc, OSU Extension forage specialist recently wrote a good article about forages with prussic acid poisoning potential and ways to manage those forages in a grazing, silage, or hay harvesting system.  That entire article is available on the OSU Extension Beef Team website at or contact the Wayne County Extension office at 330-264-8722 for more information.