Effects of a deoxynivalenol contaminated diet on feed intake and health status in horses

Twelve geldings were randomly assigned to one of the following treatments: 0 μg (control), 50 μg or 75 μg deoxynivalenol (DON) per kilogram of body weight (BW) via DON-contaminated wheat (18.6 mg DON/kg as fed) for 21 d. The total wheat intake was adjusted to 4 kg and comprised different proportions of contaminated wheat depending on the treatment group. Two kilograms of wheat plus 0.85 kg haylage/100 kg BW was provided twice a day. Blood samples were collected at predetermined times for serum DON and de-epoxy-deoxynivalenol (DOM-1), serum albumin and globulin concentrations as well as serum liver enzyme activities. Wheat intake was significantly influenced by the level of DON exposure, decreasing with the provision of 75 μg DON/kg BW. The negative impact on feed intake of DON-contaminated wheat was confirmed in a free choice feeding study by an immediate total refusal of DON-contaminated wheat or corn. There was no negative effect on haylage intake, serum albumin and globulin concentrations or serum liver enzyme activities. Serum DON increased with increasing DON intake in a linear manner. Negligible serum DOM-1 concentrations were only detected on day 21 of DON exposure, suggesting that DON was absorbed in the small intestine in its nonmetabolized form to a large extent and/or poorly degraded to the less toxic metabolite DOM-1 in the hindgut. During the 21 d of DON intake, results reflect an aversion response, possibly mediated through a cognitive effect. However, the immediate refusal to consume the DON-contaminated wheat or corn during the free choice feeding trial suggests that the impact on feed intake is probably due to sensory changes within the DON-infected wheat rather than post ingestion central effects.