Estonian Academic Agricultural Society Agraarteadus 2228-4893 25 1 2014 6 20 Mycotoxin contamination in grass and maize silage in Estonia Rohu- ja maisisilode mükotoksiinidega saastatus Eestis 23 29 ET Helgi Kaldmäe Estonian University of Life Sciences, Institute of Veterinary Medicine and Animal Sciences, F.R. Kreutzwaldi 62, Tartu 51014, Estonia. helgi.kaldmae@emu.ee Andres Olt Estonian University of Life Sciences, Institute of Veterinary Medicine and Animal Sciences, F.R. Kreutzwaldi 62, Tartu 51014, Estonia Ragnar Leming Estonian University of Life Sciences, Institute of Veterinary Medicine and Animal Sciences, F.R. Kreutzwaldi 62, Tartu 51014, Estonia Meelis Ots Estonian University of Life Sciences, Institute of Veterinary Medicine and Animal Sciences, F.R. Kreutzwaldi 62, Tartu 51014, Estonia The silage quality estimated by chemical composition and fermentation parameters, but awareness of the composition of mycotoxins is of great importance. The aim of this study was to determine the concentration of the mycotoxins (deoxinivalenol (DON) and zearalenon (ZEA)) in silage produced on Estonian farms (n=56), in the years 2011, 2012 and 2013. A total of 596 grass, 55 maize and 10 whole-crop silage samples were collected for analyses. The silages were found to contain mycotoxins. In grass silage, 92% of samples were found to be positive for DON and 100% for ZEA, while in maize silage samples 95.7% were positive for DON and 100% for ZEA in 2013. The mean concentration of DON of grass silage was 209 ppb while the concentration of ZEA was 329 ppb. In maize silage the mean concentrations of DON and ZEA were 227 ppb and 292 ppb respectively. ZEA concentration in first-cut grass silage was a mean of 257.4 ppb, the second cut 245.0 ppb and the third cut 224.4 ppb, while the figures for DON concentrations were 214.7 ppb, 190.8 ppb and 166.3 ppb respectively. Silage with a dry matter content of <25% contained fewer of the analysed mycotoxins compared to silages with dry matters of 35–45%. During the growing period grass forage was contaminated with mycotoxins, most of all by DON and ZEA. Mycotoxin concentrations increased in the field before the forage was cut for silage making. The ZEA and DON concentrations increased by with increased growth time of the forage. The maximum levels of mycotoxin contents of the grass were recorded at the time of harvest. DON and ZEA concentrations in the summer period depended on the grass species and the weather conditions.