On-farm factors relating to mycotoxin occurrence and other chemical compositional traits in grass silages in Ireland

Many pre- and post-mowing on-farm traits influence mycotoxin occurrence and conventional chemical composition in grass silages. The objective of this study was to determine if observed on-farm pre-or post-mowing factors can be used to indicate mycotoxin occurrence or conventional chemical composition traits in grass silages. Over a two year period (2012-2013 and 2013-2014) 290 grass silages were sampled on 145 farms and these consisted of baled (n=115) and pit (n=175) silages. On each farm in each year, a questionnaire was completed and pre- and post-mowing factors recorded. The preservation quality was better in pit compared to baled silages in both years and in silages made in Year 2 compared with Year 1. On-farm pre- and post-mowing factors were generally not secure indicators of silage conventional chemical characteristics. In contrast, the occurrence of enniatins and beauvericin generally increased with harvesting month (May-October) for grass silages. Visible mould on baled grass silages and a rotted top layer with pit grass silages were associated with andrastin A, mycophenolic acid and roquefortine C occurrence.