On the effects of deoxynivalenol (DON) in pig feed on growth performance, nutrients utilization and DON metabolism

Control wheat and wheat artificially inoculated with Fusarium culmorum and as well as wheat contaminated mainly with deoxynivalenol (DON) were gradually blended to yield diets for pigs with increasing DON concentrations (0.2, 0.7, 1.2, 2.5, 3.7 mg/kg) at a total wheat content of 400 g/kg diet. Performance was recorded over a liveweight range between 34 and 104 kg (n=l 8 per group). Blood was drawn from the jugular vein after five weeks on the experimental diets to determine the clinical-chemical parameters and DON concentrations. In addition, a balance study was carried out with the groups fed the diets with the lowest and the highest DON concentration to test the effects on nutrient digestibility and DON metabolism. DON and its metabolite de-epoxy-DON were analysed in physiological samples by HPLC after cleanup by immuno-affinity columns (IAC). Performance of pigs was not significantly affected by increasing dietary DON concentrations, although there was a trend toward a decrease in weight. This was especially true for the group fed the diet with 3.7 mg DON/kg, which consumed 5% less feed and gained 8% less liveweight than the control group. Serum clinical-chemical parameters, such as albumin, total protein, GLDH, ASAT, γ-GT and immunoglobulins were not influenced by the dietary treatments. DON concentration in serum increased in a dose-response-related manner and did clearly reflect the DON exposure of the animals. However, adverse effects on performance were only obvious for the group fed the diet with the highest DON concentration. No significant differences were found for nutrient digestibility of the tested diets. With regard to the DON balance and metabolism, urine was the main excretory route. A total of 52.3% of the ingested DON was eliminated as the parent toxin whereas 2.6% was excreted as the metabolite de-epoxy- DON in the group fed the diet with 3.7 mg DON/kg. The excretion of both substances accounted for approximately 98% of the total DON recovery from urine and faeces, which indicates the important role of the urinary elimination route. De-epoxy-DON accounted for approximately 5% of the urinary excretion of de-epoxy-DON plus DON, whereas in faeces a ratio of approximately 97% was found, which underlines the role of the digestive tract in the metabolism of DON in the pig.