Study: Cows done in by bad spuds

Jan. 28, 2011

by Terry Devitt

Anyone taking the recent, mysterious deaths of 200 steers in a Portage County, Wis., feedlot as a sign of the apocalypse can rest easy. The cows, according to the Wisconsin Veterinary Diagnostic Laboratory, were done in by bad spuds.

Specifically, the cows were poisoned by a toxin found in moldy sweet potatoes, which apparently were mixed in with potato waste fed to the animals. Tests on feed samples revealed the presence of ipomeanol, a mycotoxin found in moldy sweet potatoes, says Peter Vanderloo, associate director of the lab.

"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," Vanderloo explains.

Sweet potato waste was a major component of the animals' diet at the time of the Jan. 14 incident, he notes. It is a common practice in agriculture to feed animals food that cannot be used for human consumption. In this case, the potatoes were never in the human food supply chain, Vanderloo explains, and there is no risk to human heath.

It was first suspected that a virus or other pathogen might have been responsible, Vanderloo says, because the animals exhibited symptoms consistent with pneumonia. However, laboratory tests found no evidence of any of the major viral pathogens that could cause a respiratory disease such as pneumonia. "None of the major respiratory pathogens of cattle were identified in the samples provided to the lab."

The lab looked for bovine herpesvirus, bovine viral diarrhea virus, bovine respiratory synctial virus and corona virus and found no evidence for those or any other pathogens, according to Vanderloo.

The deaths of the Wisconsin cattle, reported shortly after other mass die-offs of birds and fish, was reported widely and fueled wild speculation as to the cause, linking the deaths to everything from the end of the Mayan calendar to the second coming and the apocalypse.

The Wisconsin Veterinary Diagnostic Laboratory, established in 1938, is the primary state laboratory providing diagnostic services and disease surveillance tests for farmers and others to detect a wide variety of animal diseases and pathogens that affect domesticated and wild animals.