Although many of the mass animal deaths reported around the world in the past month remain unexplained, officials have closed the case on the mystery of 200 cows that dropped dead in Wisconsin on January 14. A toxin from moldy sweet potatoes, which were a part of the animals' feed, are to blame for the bovines' seemingly strange demise.
While officials initially believed a virus such as infectious bovine rhinotracheitis (IBR) or bovine virus diarrhea (BVD) could have caused the 200 deaths at a Portage County farm, further testing revealed pneumonia to be the likely culprit, though such widespread cases of pneumonia are rare. The Wausau Daily Herald reports that the cattle's feed was then sent for testing, and the lab results from Friday revealed that a mycotoxin commonly occurring in moldy sweet potatoes, ipomeanol, was found to have triggered the pneumonia that caused the 200 cows to die.
According to AolNews, officials attest that the spoiled potatoes were not in the human food supply chain, and therefore pose no threat to people.
Yahoo News reports that similar cases of decaying sweet potatoes triggering cow deaths have been documented in 2007, 2003 and 2001.