US | mysterious animal deaths Here's What Killed Those Dead Cows Toxic sweet potatoes were included in their feed By Evann Gastaldo Posted Jan 31, 2011 1:38 PM CST Copied The cows were done in by sweet potatoes. (?karlfrankowski) The latest mass animal death mystery has been solved: The 200 cows that dropped dead in a Wisconsin pasture two weeks ago were killed by, of all things, moldy sweet potatoes. The farmer who owned them originally suspected disease, but investigators ruled that out and determined the cows were likely poisoned by the spoiled sweet potatoes, which were included in their feed, Aol News reports. Click here for more. Read These Next Trailer for Ryan Gosling's Project Hail Mary scores a record. The Giants celebrate a 'once-in-a-century' home run. Judge blocks Trump's birthright citizenship ban. Missing teen surfer found alive on uninhabited island. Report an error