MYCOTOXINS – THE INVISIBLE COMPONENT IN FEED
FEED AND BEDDING FOR HORSES ARE NATURAL PRODUCTS. FOR THIS REASON, A NATURAL POPULATION OF MICROORGANISMS IN FEED OR BEDDING IS QUITE NORMAL. THESE ARE ALSO TOLERATED BY THE HORSE IN CERTAIN QUANTITIES.

How do mycotoxins develop?
Fungi form mycotoxins due to unfavorable conditions during harvesting in the field or incorrect storage. To date, more than 400 secondary metabolites with toxic potential are known. Although correct harvest management and proper storage reduce mycotoxin formation, mycotoxins are often present in feed in increased quantities (VERVUERT 2020).
How do I find out if the food is contaminated with mycotoxins?
Feed samples can be tested for mycotoxins in various laboratories using rapid tests. This is possible, for example, at the LUFA NRW. This allows you to quickly find out whether hay, straw and other feedstuffs are still suitable for feeding.
How sensitive is the horse to mycotoxins?
How sensitive are horses to mycotoxins? It has been known for many years that certain molds also have a toxic effect on horses and therefore have a negative impact on health and performance. The results of the study by LIESENER (2012) show that mycotoxins are frequently found in single and compound feedstuffs for horses, but that the legal guideline and maximum values are not exceeded. However, straw with qualitative restrictions also frequently brings mycotoxins into the stable (KLUWE 2006). The coarse feed, which forms the basis of every ration for horses, is often contaminated with harmful fungi. Especially late grass cuttings, which are common in horse feeding, are affected by increased bacterial contamination. This is not only problematic for the respiratory tract (LfL n.d.), but also for the whole organism if the mycotoxins enter the bloodstream via the digestive tract.
The effects in horses are varied and depend on the strain of fungus:
Effects of various mycotoxins in horses:
Zearalenone – can lead to fertility disorders (GIMENO and QUINTALNILLA 1983), damage to the sperm chromatin structure (MINERVINI et al. 2010))
Deoxynivalenone (T2 toxin/ HT-2 toxin) – reduced feed intake (RAYMOND et al. 2003), disturbances of the central nervous system (Greenway and Plus 1976), but overall less sensitive (JOHNSON et al. 1997)
Trichothecenes – Blindness, coordination disorders, liver changes (LfL n.d.)
A high content of mycotoxins puts a strain on the liver and reduces its detoxification function. This leads to damage to the cells and thus weakens the immune system (LFL n.d.)
Compared to other farm animals, horses appear to be more tolerant to individual mycotoxins, as there are only limit values for fumonisins (LIESENER 2012). Nevertheless, horses ingest mycotoxins from different sources and the sum of different mycotoxins could have an impact on health. Further research is needed here.
In order to prevent some of the mycotoxins from entering the bloodstream via the intestine and ultimately reaching important organs, the use of mycotoxin binders can be useful. Bentonite has proven its worth in pigs (Horky et al. 20121). The special surface structure reduces the absorption of toxins in the intestine and thus reduces the harmful effects in the body (CARSSON and SMITH 1983).
If it is suspected that the straw or hay in the stable is contaminated, it makes sense to support the horse's digestive tract. Mannanoligosaccharides (MOS) and ß-glucans are natural components of brewer's yeast and are found in its cell wall. They have a positive effect on the intestines by supporting the microbiome and strengthening the intestinal mucosa. As a result, they help the intestine to better protect itself against harmful intruders such as viruses, bacteria and fungi. The ß-glucans also support the immune system. MOS also have the ability to bind harmful substances such as mycotoxins and, in some cases, pathogens, thereby removing them from the body (LEIBER GMBH 2022). Various herbs and other plant components such as oregano, arnis and cinnamon can also support digestion.