Guidelines to Avoid Prussic Acid, Nitrate
Poisoning
Drought conditions make 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. ©
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