Abstract

Aflatoxins are secondary toxic metabolites produced mainly by Aspergillus flavus andAspergillus parasiticus that contaminate food and feed. Due to the high incidence of AFM₁in milk that have been reported at the Hamadan region in Iran, a study was conducted to identify the cow feed mycoflora with special respect to aflatoxigenic fungi. 186 cows feed samples from traditional- and industrial-dairy farms of Hamadan region were examined using dilution plating technique in summer and winter seasons. The predominant fungi isolated were Aspergillus species (37.4%) (Aspergillus clavatus, A. flavus, Aspergillus fumigatus, Aspergillus nidulans, Aspergillus niger, Aspergillus ochraceous, A. parasiticus, Aspergillus terreus, Aspergillus ustus) followed by, Penicillium (23.7%), Fusarium(17.5%), cladosporium (9.1%), Alternaria (4.3%), Rhizopus (3.9%) and Mucor species (3.4%). The concentrate feed was the most contaminated feed, for which the mean colony counts for A. flavus and A. parasiticus were 7.25 × 10² and 7.50 × 10² cfu/g, respectively. The most contaminated feed with these two Aspergilli was concentrate feed (80%) in summer and wheat bran (45%) in winter. The mean colony count of aflatoxigenic fungi in industrial-diary farms was significantly higher than traditional-dairy farms. Moreover, the mean of aflatoxigenic fungi colony count in winter was significantly greater than those in summer seasons (p < 0.00001). The present study tested the hypothesis that differences exist between fresh forages used in summer and the ensiled form used in winter in terms of contamination with aflatoxigenic fungi.

Key words: Animal feed, Aspergillus, aflatoxigenic, food contamination, mycoflora, Iran