Mycotoxins occurrence and fungal populations in different types of silages for dairy cows in Spain

Silages constitute a major component of the feed ration for dairy cows, being a potential source of mycotoxins due to the possible contamination by filamentous fungi capable of producing these toxic compounds. In this study, samples of different kinds of silages collected from farms located in four regions of Spain, were analysed to evaluate the occurrence of aflatoxins (AFs) and Fusarium mycotoxins. Lactic acid bacteria and fungal populations as well as pH and water activity were also studied. Penicillium, Geotrichum and Monascus were the main fungi identified in all the silages examined. The incidence of AFs was low (10 % of positive samples). Fusarium mycotoxins were detected in 40 % of the samples and fumonisins (FBs) were the most commonly detected. Maize silage was the most heavily contaminated type of silage. Levels of mycotoxins detected in positive samples did not exceed the EU guidance values. The lack of relationship between Fusarium counts and its mycotoxin concentrations suggested that mycotoxin production possibly occurred pre-ensiling or immediately post-ensiling. Outcomes showed that mould growth and mycotoxin contamination in silages should be regularly monitored in order to minimize the exposure of dairy cows to contaminated feed. This work was supported by the Spanish Ministry of Economy and Competitiveness (project AGL2014-55379-P). María Rodríguez-Blanco thanks the University of Lleida for a pre-doctoral grant. The authors would like to thank Montserrat Prim for her technical assistance.