These harmful toxins produced by molds and fungi could be lurking in your horse’s feed and forage

Did you know there are toxic substances tucked away in your horse’s feed and forage? You can’t see them, and you can’t eradicate them, but chances are these compounds, called mycotoxins, are present.

Specific molds and fungi produce mycotoxins in soils, grains, and forages when environmental conditions are favorable. Once produced, they are generally very stable and will persist for a long time during storage. Horses that consume grains and forages contaminated by mycotoxins can suffer from a variety of health issues. As horse owners we should be particularly concerned, says Max Hawkins, PhD, nutritionist with Alltech’s mycotoxin management team, because mycotoxins inhibit protein synthesis, which negatively impacts the animal’s physiology and ability to function and repair tissues. 

The molds that produce mycotoxins are visible on contaminated feed. However, the mycotoxins can still be present after the mold dies or falls off the feed. These molds can be classified as either field fungi, which grow on plants while they are still rooted in the ground, or storage fungi, which develop after plants are harvested and stored. Field fungi require high moisture conditions (20-21% moisture), while storage molds can grow at lower moisture levels (13-18%). Forage and feed producers and property managers should monitor both moisture and temperature levels carefully so they can be aware of the potential for mycotoxin-producing molds to form. Horse owners should learn to recognize the signs of mycotoxin exposure so they can have their veterinarian out to assess the horse, diagnose the problem, and start a recovery plan. 

How Harmful are They?

It is near-impossible to find grain, pasture, and hay that is completely mold- and mycotoxin-free. In a 2010 study, German researchers Liesener et al. found at least one type of mycotoxin in each of 62 samples of commercial horse feeds, with many samples having more than one. However, the levels present were well below dangerous. So instead of taking on the impossible task of eliminating mycotoxins, owners should focus their efforts on minimizing their horses’ exposure to these elements