Aflatoxin accumulation in whole crop maize silage as a result of aerobic exposure

Most of the maize silage stored in horizontal silos is exposed to air and can be spoiled by fungi. Potentially toxigenic fungi have been found in maize silage, and about 300 mycotoxins have been detected. Among these mycotoxins, the most harmful for feed and food safety are aflatoxins. The aim of the study was to set up a specific method to detect aflatoxins in maize silage, and to investigate whether aflatoxin contamination in maize silage depends on the level of field contamination of the crop, and whether the occurrence of aerobic spoilage during ensiling has any effect on the final contamination of the silage.

A method for the determination of aflatoxin B(1), B(2), G(1) and G(2) in maize silage using high-performance liquid chromagraphy with fluorescence detection has been developed and validated. Recoveries of aflatoxin B(1), B(2), G(1), and G(2) spiked over the 0.25 to 5 µg kg(-1) range averaged 74-94%. The results of laboratory scale and farm scale ensiling experiments indicated that aflatoxins could increase when silage is exposed to air during conservation or during the feed-out phase.

The method here proposed to detect aflatoxins in silages has proved to be sensitive and is able to detect levels of 0.1 and 0.5 ng mL(-1) for AFB(1) and AFG(1), and between 0.025 and 0.125 ng mL(-1) for AFB(2) and AFG(2). This study also provides evidence of aflatoxin accumulation in whole crop maize silage as a result of aerobic exposure.