LIGHT FROST CAN CAUSE PRUSSIC ACID

 Light frost can cause toxic levels of prussic acid to occur in many annual forages.  While many plants contain the toxic materials, the greatest culprits are Johnson grass, hay grazers or forage sorghums-sudan hybrids, and various millits. Cattle may succumb to prussic acid poisoning while grazing these forages if they have become drought stressed or in the fall after a light frost.  Livestock should not be allowed to graze these plants in a stressed condition as death can occur.   Prussic acid poisoning acts rapidly and can kill animals within minutes.  Symptoms may include a brief period of stimulation followed by depression and paralysis.  Signs of colic may be present. Stupor (loss of sensibility), difficult breathing and frequent convulsions may result. Death is actually caused by suffocation since oxygen remains in the blood and is not exchanged to the tissues.  Testing for prussic acid in these forages is possible, however, a true accuracy is unpredictable because many plants in the field may have prussic acid and many may not.  Just remember a couple of bites of the poisonous plant can result in death.  Producers do have an option of swathing forage sorghums that have prussic acid. When swathed, prussic acid leaves the cut forage when allowed proper time to cure before bailing.  However re-growth of plant material may still be toxic. Producers turning into new pastures that have not been grazed should also be cautious to the fact that there could be many colonies of Johnson grass growing.  These Johnson grass colonies could contain Prussic Acid.  The best management option is to wait 7-10 days after a killing freeze before turning cattle into new pastures, hay grazer, or sorghum stubble fields.  The 7-10 days will allow the prussic acid to leave the plant just like swathing the hay and letting it cure.  For more information, contact the Wheeler County Extension Office at 806-826-5243.