Nutritionist > Equine
Trichothecenes (T-2 toxin, diaceptoxyscripenol (DAS), deoxynivalenol (DON), HT-2 toxin, etc.)
Trichothecenes are typical field mycotoxins and are produced on crops entering feedstuffs via contaminated ingredients.
Trichothecenes are produced by several fungi including Fusarium, Stachybotrys, Trichoderma, Myrothecium and Trichothecium, however Fusarium is the main species implicated in the production of trichothecenes. Trichothecenes are found more commonly in Europe and one hundred and eighty toxins are known to be produced by Fusarium species in cereals and forage.
Clinical signs of trichothecenes toxicity include:
- Oral lesions
- Reduced feed intake
- Weight loss
- Immune suppression
- Poor performance
- Colic
Stachybotryotoxicosis was first described as an often fatal disease associated with mouldy hay and straw in Russia.
DON (deoxynivalenol) is more commonly known as Vomitoxin, as it induces vomiting in dogs and pigs. Horses do not have the ability to vomit but will refuse feed containing DON and will therefore lose condition, this is particularly significant for competition horses. DON is commonly found in maize and wheat and although wheat per se is not a common ingredient in horse feed, wheat bran and by-products are. Wheat straw is also commonly used for horse bedding. DON seems to be produced following alternating hot and cold temperatures. There is little research concerning DON’s effects on horses, but research carried out by North Carolina State University, showed the presence of DON in the concentrate feed of 100% of colic cases with values ranging from 0.2 – 8.3 ppm, and 70% of the control fed concentrates with values ranging from 0 – 2.5 ppm. In addition, T2 toxin concentrations greater than 0.5ppm and zearalenone greater than 0.7ppm were found in 31 and 44% of the colic cases respectively with neither being present in the control group. This paints a confusing picture.
In Germany a large group of Warmbloods (n=104) suddenly lost weight in 2002. The straw bedding was found to be contaminated with DON at a level of 0.5-2.7ppm. In addition they had elevated liver enzymes. Following removal of the bedding, the condition of all horses improved.
Until further research becomes available for horses, it is suggested that the maximum tolerable level of DON in the total feed should be 2ppm.
There has been only one trial involving feeding T2 toxin to horses and when fed at a level to mimic a concentration of 1ppm in the feed, no effect on the ovarian activity of mares was seen.
