Identifying Aflatoxin Exposure Risk from Supplemental Feeding of Deer

Aflatoxins, common contaminants of crops and feed, are a health risk to wild and domestic animals. Past research found aflatoxins in feed and feeders provided for wild herbivores valued for recreational hunting (hereafter: game) species but are consumed by various species. We determined the current extent of aflatoxin contamination in wildlife feed and white-tailed deer (Odocoileus virginianus) feeders, examined aflatoxin production in corn piles over time, and quantified nontarget wildlife visitation to deer feeders. We sampled feeders (n=107) in Mississippi, US, bagged/bulk feed sources (n=64) in the southeastern US, as well as corn piles exposed to environmental contamination over 10 d (n=20) during May-January of 2019 and 2020. We found aflatoxins (≥5 parts per billion [ppb]) in feeders during summer (4% prevalence, 58±71 ppb mean±SD) and hunting season (October-January, 6%, 60±1 ppb) and in bagged/bulk feed during hunting season (11%, 13±8 ppb). After 8 d, aflatoxins were detected in all summer corn piles at toxic levels (483-3,475 ppb), although none were detected in hunting season piles after day one. Nontarget wildlife identified at feeders included 16 mammalian and 18 avian species. Numerous wildlife species are at risk for aflatoxin exposure due to supplemental feeding of deer, with the primary risk factor in the southeastern US being summertime environmental exposure of feed to aflatoxin-producing fungi.