Drought conditions in much of Kansas are making forages more susceptible to prussic acid or nitrate poisoning, say officials at Kansas State University.
Prussic acid, a derivative of cyanide, may be present in drought-stressed corn and grain sorghum (also known as milo). Farmers seeking to salvage stunted crops often put cattle in fields to graze those crops. Drought-stunted crops can accumulate cyanide and build toxic levels of prussic acid when they're mature.
Prussic acid also is suspected as the recent cause of death of cattle grazing Johnsongrass in Comanche County, according to reports from K-State Research and Extension county and area agents.
It is generally the lower six inches of the crop that harbors prussic acid, said K-State officials, who offer these guidelines for producers:
- Do not allow hungry cattle to graze where prussic acid may be a problem;
- Do not allow animals to graze potentially troublesome plants after a light frost or after rain that has ended a summer drought.
- Chop or ensile plants high in cyanide to reduce toxin levels;
- Have representative samples of any suspect forage analyzed before feeding.
K-State Research and Extension officials also are warning against forages that may be high in nitrates, another potential danger of grazing drought-stressed crops. Forages that contain high levels of nitrates also can cause death, though not as quickly as prussic acid poisoning. In fact, some animals can adapt to increasing amounts of nitrate in feed. If cows are exposed to high levels of nitrate, there is an antidote that can be given to them.
All livestock are susceptible to nitrate toxicity, but cattle and horses are affected most often.
The guidelines to reduce nitrates in forages include:
- Pay close attention to potentially troublesome plants, such as sorghum and sudangrass, which often have high nitrate levels.
- Avoid excessive application of manure or nitrogen fertilizer.
- Raise cutter bar 6 to 12 inches to exclude basal stalks. This also will minimize harvesting many weed species that have accumulated nitrate from shading.
- Delay harvesting any stressed forages. A week of favorable weather is required for plants to reduce accumulated nitrate.
- Never feed green chop that has been heated after cutting or held overnight.
- Harvest plants containing high levels of nitrate as silage rather than hay. ©
