Both cyanide (prussic acid) and nitrate can be present in various amounts in many grain and forage sorghum crops that are stressed by hot, dry conditions. Cyanide poisoning is the more likely risk, though nitrate/nitrite poisoning is also a possibility when grazing sorghum during drought.
Hay made from sorghums containing toxic amounts of cyanide, nitrate or both will remain dangerously toxic. Ensiling the crop significantly reduces or eliminates these risks.
However, cyanide poisoning is often overrated. Additionally, the fear of it - realised when people avoid the use of valuable crops - may cause more loss than actual poisoning would.
The number of deaths due to poisoning is very small considering the number of animals grazing sorghums. Nonetheless, it is always a threat, particularly under drought conditions. You can prevent serious losses by observing a few simple rules.