Aflatoxins have turned up in some corn crops this fall, particularly in areas that experienced hot, dry weather during the growing season. Improper storage can result in increased levels of the toxin in corn. Beth Doran, a beef field specialist with Iowa State University Extension, says beef producers should test feeds for aflatoxin to prevent performance and reproduction losses, and potentially death loss in cattle. FDA guidelines list limits of aflatoxin in corn fed to cattle at 100 parts per billion for breeding cattle, 300 ppb for finishing cattle and less than 20 ppb for young animals.