The process of prussic acid formation in genus Sorghum occurs when HCN, a type of hydrogen cyanide acid, enters the environment of Sorghum grass. It is a triple chemical bond between hydrogen, carbon, and nitrogen. It takes nineteen pounds of mature sorghum or to 7 ½ pounds of young sorghum to kill cattle. These numbers only reflect acid that has already entered the animal’s blood stream. Generally, cattle will consume more than this amount before the symptoms present.
Strategies to Reduce Poisoning
Dried varieties of sorghum have less prussic acid in it. Growing these grasses in poor soil, especially those with fewer nitrates, can reduce the amount of prussic acid in the crop. Grasses taller than eighteen inches are safer and do not generally have the poison compound. Sorghum that has no green showing also will not harm livestock. Chemists know that hybrids of the species also have less incidence harming livestock.
Toxic Conditions
Grasses injured by drought or other climatic conditions have increased amounts of acid in it. Research shows that more than twice the quantity in found in drought stunted or frost-bitten grasses of the sorghum or Sudan variety. Again, chemists and farmers agree that younger grasses are more toxic to livestock than older grasses.
Sorghum Crops
Many types of these grass species exist. Common varieties are sorghum bicolor, bicolor drummondii, and halepense that contain potential for HCN. Worldwide, Sorghum bicolor is a common food grain.
Symptoms
Symptoms of this type of toxicity include gasping, convulsions, and respiratory distress resulting in death. The nose and mouth of the affected animal(s) turn a bright pink color. If caught early, the animals can fully recover. Within twenty minutes of eating the poisoned grass, the animal will display symptoms.
Areas of Highest Risk
Places north of the 35 latitude are most at risk for this type of poisoning. States near the Gulf Coast have little or no incidence. Farmers in New South Wales also have troubles with this type of poisoning. The main reason for the problems in growing is that sorghum is a tropical or subtropical plant meant to grow where temperatures are warm year-round.
Most Toxic Parts of Blade
The outer tissue of the grass blade has the cyanide while the leaf has the enzymes that produce the toxic effects. Though the poison is on the grass blade, no reaction happening until something disturbs the grass.
Mimic Diseases
Other types of poisoning mimic prussic acid poisoning like nitrite poisoning, acute pulmonary oedema and emphysema, blue-green algae, and anaphylactic reactions.
