Evaluation of zearalenone, α-zearalenol, β-zearalenol, zearalenone 4-sulfate and β-zearalenol 4-glucoside levels during the ensiling process

Abstract

Zearalenone-producing Fusarium species can contaminate maize before ensiling and cause reproductive problems in animals. Suspect feeds are only routinely analysed for zearalenone (ZEA), not considering other oestrogenic metabolites or masked derivatives. The aims of the present study were to monitor the levels of ZEA, α-zearalenol (α-ZOL), β-zearalenol (β-ZOL), zearalenone-4-sulfate (ZEA-4S) and β-zearalenol-4-glucoside (β-ZOL-4G) in artificially contaminated maize silage and determine the effect of the ensiling process on these toxins. A laboratory silo model was designed using polystyrene bags filled with previously contaminated chopped whole-plant maize, stored in a dry and cool room and sampled at days 7, 45, 90, 120 and 127. ZEA, α-ZOL, β-ZOL, ZEA-4S and β-ZOL-4G levels were quantified by liquid chromatography – tandem mass spectrometry. Chemical and physical analysis indicated silage maintained good quality in all stages. pH was reduced favourably (P<0.05) from 4.69 to 3.80 during the preservation stage. Dry matter, moisture content and water activity did not vary from day 7 to 127. ZEA, α-ZOL, β-ZOL and ZEA-4S levels also did not change from day 7 to 127, indicating no significant degradation by the ensiling process or silage-native microbiota. This study suggests that ZEA levels remain invariable during the ensiling process, as well as the levels of its derivatives. The presence of highly oestrogenic metabolites, like α-ZOL and the masked ZEA-4S, which are not screened in the routine analyses, increases the overall toxicity of ZEA-contaminated silage.