Abstract
Practical applications Fifty poultry feed samples were collected from five regions (Hail, Jeddah, Makkah, Qassim and Al-Madinah) in Saudi Arabia, 10 samples from each region. Thirty-two fungal species belong to 16 genera were isolated on both Dextrose Czapeks and Pototo dextrose agar media at 28 degrees C using two isolation methods (dilution-plate and baiting methods). The most common species were Aspergillus flavus, Aspergillus niger, Aspergillus tamarii, Aspergillus terreus, Aspergillus versicolor, Emericella nidulans, Fusarium oxysporum, Mucor racemosus, Neurospora crassa, Paecilomyces variotii, Penicillium chrysogenum, and Rhizopus stolonifer. Qualitative determination of aflatoxins in 24 isolates of A. flavus and Aspergillus parasitcus were screened using ammonium hydroxide test. Fourteen isolates (58.3% of total isolates) exhibited positive reaction when exposed to ammonium hydroxide vapor. However, 10 isolates (41.7%) showed negative response for their abilities to produce aflatoxins. High performance liquid chromatographic analysis of cultural extracts exhibited variable levels of aflatoxins. The concentration of aflatoxin B was 18.0-204.8 ng/ml. However, aflatoxin G was 21.7-249.3 ng/ml. Culture extracts of A. flavus and A. parasiticus were also analyzed by thin layer chromatography (TLC) for aflatoxins detection. Fifteen isolates (62.5%) exhibited distinct spots for aflatoxins on the TLC plate. Aflatoxin B was predominant. The R-f values of B-1, B-2, G(1), and G(2) were 0.78, 0.62, 0.46, and 0.38, respectively. Study of fungal content of poultry feed would contribute to know the aflatoxins producing fungi and avoid the hazard effect of these fungi by storing of feed in unsuitable conditions for germination and metabolites of these fungi. The ability of Aspergillus fungi to produce aflatoxins and concentration of aflatoxins in the culture extracts of these fungi give evidence for how much doses of aflatoxins expose to poultry industry and its negative impact on poultry production and human health.