The Fungus Flora of Cattle Feeds

Abstract

SUMMARY The fungus flora of 26 feed samples, 16 of which had histories associated with disorders of livestock, has been determined and compared to that of non-suspected feeds. Visual and stereomicroscopic analyses of the feed substrates showed that the samples were generally heavily contaminated with molds, other micro-organisms, soil, feces, and debris. Special techniques of isolation and the employment of a wide range of natural and synthetic media, viz., malt-salt, malt-extract, Czapek-Dox, Littman oxgall and potato-dextrose media permitted isolation of a variety of fungi. The formation of discrete colonies on malt-salt generally allowed quantitative determinations of the number of colonies of fungi from dilutions of washings as well as easy isolation in pure culture. Littman oxgall agar permitted the isolation of several species not encountered on the other media. Malt-extract and potato-dextrose agars generally permitted rapid growth of the molds. Czapek-Dox was highly specific for isolation as well as culture of members of the Aspergillaceae and certain Moniliaceae. Sixty-four species representing 3 classes, 7 orders and 12 families were found on the external surfaces of the feed materials. Only 14 of this number were found to occur both externally and internally. Of the 64 species identified, 63 were obtained from suspected samples and 38 of these were isolated also from non-suspected feeds. The following species isolated have known or suspected pathogenic or toxic abilities in cattle or other livestock: Mucor flavus, M. racemosus, Rhizopus arrhizus, R. nigricans, Haplosporangium decipiens, Candida albicans, C. humicola, C. krusei, Cryptococcus albidus, Aspergillus chevalieri, A. flavus, A. jumigatus, A. nidulans, A. terreus, Monascus purpureus, Penicillium expansum, Chaetomium olivaceum, Cephalosporium kiliense, Paecilomyces variota, Scopulariopsis brevicaulis, Trichoderma koningi, Fusarium moniliforme, Cladosporium herbarum, Pullularla pullulans, and Streptomyces spp. Members of the Aspergillaceae were predominant in the flora of 25 of the feeds studied.