Last year saw many Irish dairy farmers confirming that cow performance had been impacted significantly by mycotoxins.
These reports were further verified by surveys carried out on silages made on farms across the island.
It is generally accepted that the challenge of mycotoxins is growing. This may be due, in part, to the more accurate testing systems that are now available, plus the fact that farmers are more aware of the symptoms and impact that mycotoxins can have on animal performance.
Mycotoxins
There is a clear association between mycotoxin contamination and our changing climate causing stressful growing conditions for crops.
Forage harvesting and ensiling techniques are also being questioned. It is also evident that higher performing animals are much more predisposed to the impact of mycotoxins.
So what are mycotoxins? They are natural substances produced by moulds and fungi. They are invisible, tasteless and toxic. More than 500 different mycotoxins have been identified to date, and any animal feedstuffs can be contaminated.
These include grazed grass, conserved forages (silage, wholecrop, maize, straw), home grown and bought-in feed.
Initially, it was thought that mycotoxins were a risk if forage was dry or had visible mould. Although this is true, it is now known that these substances can be present on any forage, of any dry matter, with no visible mould and excellent clamp face management.
The moulds may have disappeared. However, the mycotoxins leave behind remain in situ.
Reducing risk
Reducing mycotoxin risk requires a multi-faceted approach. In the first instance, farmers and contractors should strive to limit slurry and soil contamination of silages.
Post-harvest mycotoxins can be caused by poor consolidation and clamp management. Farmers should remove any visible mould from the clamp and do not feed to any animals.
Problem areas tend to be down the sides and along the top of the clamp, but mycotoxins are not confined to these areas alone.
Limiting the amount of time forage is exposed to oxygen reduces the chance of mycotoxin development.
Farmers should only remove covers at the point of feeding, aim to move across the face as quickly as possible and, if needed, take half blocks.
A sharp shear grab/block cutter should be used to keep the silo face as clean and even as possible. It is also important to keep feed troughs or passages clear of any uneaten silage or total mixed ration (TMR) on a daily basis.