Accumulation of mycotoxins in forage of winter pasture during prolonged utilisation of sward.

The concentration of mycotoxins in sward depending on time of pre-utilisation in summer and date of harvest in winter was analysed during the 2000-2002 vegetation seasons. Additionally, the yield of pasture sward was estimated. Higher concentrations of ochratoxin A--respectively: 0.55 and 050 ng/g DM--were found in the pasture sward harvested in December and January when compared to the sward collected in November (0.36 ng/g DM). The average concentration of zearalenone varied from 2.74 ng/g DM in December, to 6.00 ng/g DM in November and 9.77 ng/g DM in January. The highest concentration of ochratoxin A was 1.82 ng/g DM and zearalenone 47.89 ng/g DM. The highest number of samples in which ochratoxin A exceeded the level of 0.3 ng/g DM was noted in sward harvested in January (61.1%), while in the case of zearalenone, the number of samples containing this mycotoxin at a level exceeding 3.0 ng/g DM varied from 55.6% in December to 66.7% in November and January. It seems that the percentage of ochratoxin A positive samples and the toxin concentration level in the sward of winter pastures increased during the time of sward regrowth.