So it turns out it wasn't pneumonia that killed those cows in Wisconsin -- it was sweet potatoes.
In the latest chapter of a series of mysterious mass animal deaths, 200 cows died in Portage County on January 14. Early indications were that they somehow contracted pneumonia. But now new test results say they died from eating toxic sweet potatoes.
The Wisconsin Veterinary Diagnostic Lab in Madison conducted tests on feed samples and found that the sweet potatoes contained ipomeanol, a mycotoxin found in moldy sweet potatoes.
Peter Vanderloo, associate director of the lab, said in a news release. "Based on history, clinical signs, changes in tissue and test results from our lab and a referral laboratory, it is likely that a mycotoxin from moldy sweet potato was a major factor in the disease and deaths of these steers."
The cows were actually eating sweet potato waste, which is not for human consumption. It is common practice in agriculture to feed animals food that cannot be used for humans. Vanderloo said the sweet potatoes were never in the human food supply chain and there was no risk to human health.
The testing ruled out pneumonia. "Laboratory tests found no evidence of any of the major viral pathogens that could cause a respiratory disease such as pneumonia," Vanderloo said. "None of the major respiratory pathogens of cattle were identified in the samples provided to the lab."