Ochratoxin A (OTA) is a nephron toxin that affects the kidneys. It is incredibly potent, almost as potent as aflatoxin. Although OTA affects cattle, effects are not as severe as with other toxins because it is rapidly degraded in the rumen. Rumen protozoa convert OTA to ochratoxin-α, which, while still toxic, is less so than the original compound.

OTA is predominantly produced by species of Penicillium and Aspergillus, particularly P. verrucosum and A. ochraceus.

OTA occurs in a variety of feedstuffs. OTA may be present on most cereal grains, but may also occur on beans, groundnuts, dried fruits, and in wine, beer, and coffee.

The U.S. Food and Drug Administration has no regulations or guidelines on OTA in animal feeds.

OTA may cause kidney damage and failure and causes immunosuppression. OTA is a mutagen and results in DNA strand breakage, but it is also a potential carcinogen. OTA may also result in abortions or death. Rumen degradation makes dairy cattle more resistant to OTA toxicosis. However, when dairy cattle consume too much concentrate feeds, the rumen microbial population is altered and the rumen protozoal population decreases, resulting in decreased OTA degradation.

Diaz, D. 2005. The Mycotoxin Blue Book. 295–323. Nottingham, UK: Nottingham University Press.

Whitlow, L.W. and W.M. Hagler, Jr. 2017. Mold and Mycotoxin Issues in Dairy Cattle: Effects, Prevention and Treatment. eXtension. Accessed 7/20/21.