Factors Affecting the Content of Ergosterol and Zearalenone in Selected Grass Species at the End of the Growing Season

The objective of the study was to assess the safety of forage prepared from selected grass species by means of the analysis of ergosterol and zearalenone. Graminaceous plants studied at the end of their growing season were Festulolium, Dactylis glomerata and Arrhenatherum elatius. Other indicators assessed were the content of ergosterol and zearalenone during the autumn and the intensity of grassland use in the summer season as related to the studied contents of metabolites. Grasslands were harvested either in October, November or December. The secondary metabolites were analyzed by means of high performance liquid chromatography. At the end of the growing season, the ergosterol content was the lowest in the Festulolium forage (110.04 mg kg-1), the highest contents were observed in the Dactylis glomerata and Arrhenatherum elatius forages (145.73 mg kg-1 and 139.55 mg kg-1, respectively). The safety of Festulolium was also corroborated by the low zearalenone content (0.357 mg kg-1). On the other hand, the high ergosterol content in Arrhenatherum elatius was combined with a high content of zearalenone (1.554 mg kg-1). Although Dactylis glomerata exhibited an ergosterol content comparable with that of Arrhenatherum elatius forage, its zearalenone content was comparable to the Festulolium forage. Among the three species under study we found a significant difference (P P -1). The higher (P -1) was caused by the Arrhenatherum elatius forage. Moreover, the contents of ergosterol and zearalenone were affected (P < 0.01) also by the number of cuts in summer. The higher ergosterol content indicated a higher forage infestation by fungi and the inherent risk of the occurrence of mycotoxins. However, the high ergosterol content not always correlated with the high content of zearalenone. When cattle is grazing in winter, a higher occurrence of mycotoxins in the feed may be expected and the related damage to animal metabolism may increase the number of diseased animals with consequent impact on animal production, performance and health and animal husbandry economics