Effects of deoxynivalenol in naturally contaminated wheat on feed intake and health status of horses

The present study examined the short-term effects of deoxynivalenol (DON), administered at two different concentrations via a feed preparation using naturally contaminated wheat, on feed intake, liver and kidney metabolism and immunomodulatory properties in horses. Twelve geldings were randomly assigned to one of three dietary treatments for 21 days. DON was provided via naturally contaminated wheat (14.6 ± 6.5 mg DON/kg dry matter). The daily feed intake was adjusted to 4 kg of wheat and 1.7 kg of silage per 100 kg of body weight (BW). Horses were fed one of the following diets: control wheat with 0 % contaminated wheat (CON), wheat mixture containing 53 ± 2 % of DON-contaminated wheat [low DON intake (LDI)] or wheat mixture containing 78 ± 4 % of DON-contaminated wheat [high DON intake (HDI)]. CON, LDI and HDI corresponded to a targeted daily DON intake via the complete ration of <5, 50 and 75 μg/kg BW, respectively. None of the horses demonstrated any clinical signs commonly associated with the intake of DON such as colic or depression. HDI was associated with lower daily wheat intake on day 21. Serum DON concentrations increased with higher DON intake. The non-toxic DON metabolite, deepoxy-deoxynivalenol (DOM-1) was only detected on day 21 of the DON feeding period. No changes in haematological and serum parameters or serum globulins or in the ex vivo proliferation response of peripheral blood mononuclear cells were observed. These results suggest that horses are less sensitive to DON exposure than other domestic species, for example, swine. Therefore, the European Commission guidance value for critical DON concentrations in swine feed (complete diet) of 0.9 mg/kg could be safely applied for rations intended for feeding adult horses as well.