Overview of Cyanide Poisoning in Cattle from Sorghum halepense and S. bicolor Cultivars in Northwest Italy

Abstract

Sorghum plants naturally produce dhurrin, a cyanogenic glycoside that may be hydrolysed to cyanide, resulting in often-lethal toxicoses. Ruminants are particularly sensitive to cyanogenic glycosides due to the active role of rumen microbiota in dhurrin hydrolysis. This work provides an overview of a poisoning outbreak that occurred in 5 farms in Northwest Italy in August 2022; a total of 66 cows died, and many others developed acute toxicosis after being fed on either cultivated (Sorghum bicolor) or wild Sorghum (Sorghum halepense). Clinical signs were recorded, and all cows received antidotal/supportive therapy. Dead animals were subjected to necropsy, and dhurrin content was determined in Sorghum specimens using an LC–MS/MS method. Rapid onset, severe respiratory distress, recumbency and convulsions were the main clinical features; bright red blood, a bitter almond smell and lung emphysema were consistently observed on necropsy. The combined i.v. and oral administration of sodium thiosulphate resulted in a rapid improvement of clinical signs. Dhurrin concentrations corresponding to cyanide levels higher than the tolerated threshold of 200 mg/kg were detected in sorghum specimens from 4 out of 5 involved farms; thereafter, such levels declined, reaching tolerable concentrations in September–October. Feeding cattle with wild or cultivated Sorghum as green fodder is a common practice in Northern Italy, especially in summer. However, care should be taken in case of adverse climatic conditions, such as severe drought and tropical temperatures (characterising summer 2022), which are reported to increase dhurrin synthesis and storage.

Molecular Modification Strategies of Nitrilase for Its Potential Application in Agriculture

“…Sorghum, an important feed for ruminants around the world and widely grown in Asia and Africa, also contains a cyanogenic glycoside, dhurrin, which has been shown to be rapidly hydrolyzed by the microbiota in the rumen of ruminants to release toxic HCN leading to animal toxicity. Investigations have shown that HCN content in fresh reclaimed sorghum is greater than 801 mg/kg, which is greater than the safety threshold of 200 mg/kg. , In 2022, there were cases of cattle dying after feeding hay containing sorghum on many farms in northwestern Italy, and the pathological results clearly indicated cyanide poisoning . This suggests that reducing the HCN content to below the safe threshold when handling feed can solve this problem.…”