Several cattle deaths have been reported in Oklahoma due to prussic acid toxicity in forage – also known as cyanide. How does prussic acid become a threat to grazing cattle? As producers look at alternative forages amidst declining and hard-to-find hay supplies, it’s vital for producers to know that some forages can turn deadly with particular weather, such as drought and freezes. Some forage plants in the sorghum family, including Johnsongrass, can become toxic amidst drought or frosts.

Even with minimal grazing, deaths may be seen due to prussic acid. This toxin is released when cattle begin chewing a plant with the harmless hydrocyanic glycosides. When this substance is aggravated by chewing or a swather and crimper, it converts to prussic acid and is quickly released into the rumen and absorbed by the animal’s bloodstream. To prevent prussic acid toxicity, producers should never turn hungry cattle into a new pasture.

Read more prevention tips here.