The occurrence of fungi in bovine tissues in relation to portals of entry and environmental factors.

The occurrence of fungi in tissue specimens from 72 cattle was examined by culture, histopathology and indirect immunofluorescence staining (IIF). Groups of 12 animals each had been fed either concentrate or roughage and had been housed either in tie stalls, on slatted floors or on deep bedding. Specimens were obtained from the lung, omasum and Peyer's patches of the ileum and corresponding lymph nodes. Both hyphae and spores were made visible by IIF and by combination of IIF, morphology and conventional staining it was possible to differentiate between aspergilli and zygomycetes. In the lungs, aspergilli were detected at the same rate by morphology and IIF, whereas zygomycetes were found nearly twice as often by IIF than by culture. Fungi in pulmonary tissue were most frequent in cattle tied or kept on deep bedding (P < 0.01) as assessed by IIF. Within lymph nodes only spores were found, and Aspergillus fumigatus was the predominant species. Lesions devoid of fungi, especially ulcerations, were observed on the edges of the largest omasal laminae with a notable preference for the aboral third. The localization and histopathology suggested a reflux of acid abomasal contents to be the pathogenic principle. Granulomas with centrally located plant material were found more frequently in cattle fed roughage than in cattle fed concentrate (P = 0.01) and were differentiated from mycotic granulomas.