Prussic acid poisoning problematic for beef producers

By Todd Vineyard | Published Wednesday, July 30, 2014

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What a way to cruise through July, coming off the rainfall we received two weeks ago.

This time of year we always receive calls regarding the safety of johnsongrass for cattle and horses. Actually, it’s not just johnsongrass that producers need to be concerned about. Many sorghum and sudan-type plants, including johnsongrass can release a poisonous substance known as prussic acid or hydrocyanic acid.

Even though we have had rain recently, we are still experiencing drought symptoms, and the stress put on these plants can increase your chances of prussic acid poisoning, depending on when and how you turn in your cattle.

There are some losses of cattle almost every year due to grazing on the green plants. Silage and hay can usually be fed without problems.

The prussic acid content decreases as the plant approaches maturity. Small plants, young leaves and tillers are usually the highest in prussic acid. In other words, the upper leaves will contain more acid than the older, lower leaves.

Following a rain, drought-stricken plants will have new growth or second-growth shoots on these plants that can be extremely dangerous because they are small and consist largely of leaves, which are high in prussic acid.

Nitrate poisoning can also be seen at this time. Poisoning seems to be less likely to occur if animals eat some grain and hay before they are turned into the pasture.

Most importantly, your cattle need to be full. Having cattle filled with a high-quality hay helps eliminate cattle from gorging themselves with a forage that could have prussic acid.

The remedy for prussic acid poisoning is an intravenous injection of sodium nitrite and sodium thiosulfate. However, if cattle are grazing contaminated pastures, death can come quickly.

Therefore, if you have pastures with johnsongrass present, it is advisable to have a sample sent to the Texas A&M diagnostic lab before taking an unnecessary risk.


The 2014 Ranchers Gathering has been set for Thursday, Aug. 14, at the First Baptist Church in Decatur. The trade show, featuring more than 20 agriculture-related businesses, will open at 5:30 p.m., and dinner is at 6. Cost is $10, which covers the meal and enters you in the drawing for door prizes.

Stan Bevers, professor and Extension economist – management, with the Texas AgriLife Extension Service out of Vernon, will speak about risk management tools for ranchers.

Topics will include:

  • PRF Insurance (some know it as the Rainfall Insurance)
  • PRF-Annual Forage

This program is targeted to annual forage growers who have small grain pastures and/or haygrazer production.

  • Livestock Forage Disaster Program

This is the Farm Bill program through the U.S. Department of Agriculture’s Farm Service Agency in which many producers are already participating.

This year’s event is being sponsored by the Wise County Extension Livestock and Forage Committee.

Register by Tuesday, Aug. 12, at the Extension office, 206 S. State St., in Decatur. Checks can be made to the Extension Livestock Committee.

Todd Vineyard is a Wise County Extension agent.

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