Fifty cows died from poisoning by sorghum plants at an Italian farm, and experts blame drought for the fatal accident.
The cows on the farm in Sommariva del Bosco in northwest Italy died suddenly from acute prussic acid (hydrogen cyanide) poisoning on August 6.
Prussic acid poisoning in cows is quick and extremely brutal, causing respiratory, nervous and muscular disorders. The symptoms occur 10-15 minutes after ingestion and death some 15-30 minutes later.
“We suspect that the drought caused this very large quantity of dhurrin (cyanogenic glycoside) within the sorghum plants,” said Stefano Giantin, a veterinarian at the animal health institution Istituto Zooprofilattico Sperimentale (IZS) for northwest Italy.
Dhurrin is naturally present in young sorghum plants but not in the high concentrations as those found in samples taken at the farm.
When sorghum plants grow at a normal rate, the amount of dhurrin lowers as the plants grow larger. But since the ongoing drought has slowed the growth of sorghum plants, dhurrin has concentrated inside them.
When dhurrin is digested, it releases prussic acid, which is also known as hydrogen cyanide. “Normally, it doesn’t cause death”, Giantin told news agency AFP.
The concentration of dhurrin taken from sorghum plants in Sommariva del Bosco was unusually high, which Giantin said seemed to be the result of the drought that has hit Italy this summer.
A dose of over 700 mg/kg of prussic acid is considered fatal for cows, but the animals at Sommariva del Bosco had quantities of more than 900 mg/kg in their blood.
The only way to rescue affected cows is to inject them with sodium thiosulfate to neutralise the hydrogen cyanide. This solution saved around 30 cows on other farms in the area where the same phenomenon occurred; for fourteen cows, help came too late.