Fungi flora of animal feed and aflatoxin contamination of feed and milk in dairy farms of Sabzevar County

Abstract

Introduction: Afalatoxins are among the most poisoning secondary metabolites produced
by different fungi species such as Aspergillus flavus and Aspergillus paraziticus. These
fungi contaminate different animal feed materials including oil seeds, oil seed meals and
forages. Elimination and reduction of aflatoxines in feed using biological, chemical and
physical methods of aflatroxin detoxification in large scales are not only non-practical and
cost efficient, but also are dangerous for animal health. Therefore, it seems continuously
monitoring of animal feed and products is the best method for avoiding of human food chain
contamination with these toxins. This research was conducted to investigate the feed and
milk aflatoxin contamination and their relationship with feed fungi flora in some dairy cow
farms.
Materials & Methods: Concentrate and corn silage were sampled from 5 traditional and 5
industrial dairy farm among dairy farms located around the Sabzevar county, cultivation
and identification of feed fungi were done. Milk samples were taken from cooling tank of
each farm and transferred to lab in an ice containing flask and were centrifuged to remove
fat and then stored in -22°C until analysis. Milk and feed aflatoxin were measured using
HPLC method.
Results: The most comon feed pollutants were Aspergilus, Penicillium, Trichoderma,
Alternaria, Cladosporium and Rhizopus species. The results of HPLC and fungal culture
showed a low level of aflatoxin contamination. The results of this research showed a
significant negative correlation between Aspergilus contamination and yeast population in
silage samples. Aflatoxin M1 contamination was observed in 60 percent of milk samples,
however aflatoxin amount was lower than permissive levels in all cases. Mean Aspergilus
population in concentrate and aflatoxin concentration of milk Comparison among two farm
systems, showed that relative contamination in industrial farms was significantly higher
than traditional farms.
Conclusion: Results of this research showed that aflatoxin contamination of feed and milk
was lower than permissive levels. Based on fungi culture results, it seems that concentrate
is more susceptible to fungi and aflatoxin contamination than silage.