A field outbreak of chronic aflatoxicosis in dairy calves in the western Cape Province.

An outbreak of mortality in Friesland dairy calves in which 7 out of 25 calves died in the western Cape Province, Republic of South Africa is described. Clinical signs included a loss in body mass, staring hair coat, diarrhoea and rectal prolapse. Histopathological changes in the liver were characterised by severe portal fibrosis with bile duct proliferation and mild portal round cell infiltration. The calves were fed a ration containing locally-produced maize. The implicated maize was infested with Aspergillus flavus and contained aflatoxins B1, B2, G1 and G2 with total aflatoxin levels as high as 11,790 ng g-1. This is the first report of a field outbreak of bovine aflatoxicosis in South Africa.