What to watch for when grazing forages with a higher risk of prussic acid

Ariana Schuamacher/ Agweek By Ariana Schumacher Today at 5:30 AM Listen Comments Share Share this article News Reporting News Reporting Based on facts, either observed and verified firsthand by the reporter, or reported and verified from knowledgeable sources. The Trust Project What is this? BROOKINGS, S.D. — Excess prussic acid accumulation is a concern in forages following drought years, particularly in sorghum-related forages. “Really what happens is that drought stresses those plants, of course, and then that damage to those plant tissues and cells creates a greater concentration of this acid,” said Kim Ricardo, SDSU Extension Forage Field Specialist ADVERTISEMENT Prussic acid causes quick cyanide poisoning in livestock, which can be fatal if left untreated or in severe cases. It causes issues with oxygen utilization at the cellular level, Ricardo said. Contributed / SDSU “Some symptoms include, of course, you know, labored breathing. Those animals are probably going to be staggering around, really just having some difficulties breathing. They are just not going to act quite right,” Ricardo said. “It’s kind of something you want to be on top of and try to manage, you know, as more of a preventing this from happening rather than trying to fix it once it does happen.” Prussic acid is most commonly seen in forage sorghum, sorghum sudangrass hybrids, sudangrass and Johnson grass. Ricardo said this is different from nitrate toxicity. Fields that have been hayed or drought-stressed pastures where forage growth has been stunted are a greater risk for prussic acid concerns. “I think a lot of times producers get the two confused or think that they are the same thing, but in reality they’re not,” she said. Read more What can you do with sprouted grain? 30m ago Preparing cattle for extreme weather, no matter the season 1d ago Can selling corn stover be beneficial to your operation? 2d ago Nitrates are found in most plant species, she said. ADVERTISEMENT “So there’s a wider variety of forage species susceptible to nitrate toxicity. So that is kind of one thing to recognize with prussic acid is that not all of your forage species are going to be at risk for it,” Ricardo said. “So, that kind of helps manage it in some ways.” The biggest concern rises when the forages are grazed. “Prussic acid is going to be more heavily concentrated in those young kind of leafy green parts of the plant. So it’s really a concern again following new regrowth following periods of stress or even following environmental conditions like frost,” Ricardo said. If you will be grazing sorghum species, Ricardo said to wait at least 10 days to two weeks after a killing frost to allow the plant to dry out and that prussic acid to dissipate after a light frost. However, if the plant has reached a height of 18 to 24 inches, that risk of prussic acid is a little less, so it is typically advised to wait until they have reached that height before grazing them. Producers should never turn out hungry cattle to these pastures. It’s important to make sure livestock have access to safe feed and forage prior to being exposed to potentially hazardous forages to help reduce the chance of them consuming large, potentially harmful, quantities. ADVERTISEMENT Livestock producers can take forage samples to a laboratory if they are concerned about prussic acid, Ricardo said. Most labs request that prussic acid samples be shipped overnight so the sample will be fresh. Comments Share Share this article News Reporting News Reporting Based on facts, either observed and verified firsthand by the reporter, or reported and verified from knowledgeable sources. The Trust Project What is this? Tags Tags AGRICULTURE CATTLE LIVESTOCK DROUGHT By Ariana Schumacher Ariana is a reporter for Agweek based out of South Dakota. She graduated from South Dakota State University in 2022 with a double major in Agricultural Communications and Journalism, with a minor in Animal Science. She is currently a graduate student at SDSU, working towards her Masters of Mass Communications degree. She enjoys reporting on all things agriculture and sharing the stories that matter to both the producers and the consumers. Twitter Facebook Listen to this article Conversation ADVERTISEMENT What To Read Next Corn Grazing corn stalks to combat volunteer corn 3d ago · By Ariana Schumacher Livestock Is fall grazing a good fit for your livestock operation? Nov 5 · By Ariana Schumacher Cattle Tips for transitioning calves to the feedlot Nov 3 · By Ariana Schumacher ADVERTISEMENT Get Local