Deoxynivalenol-3-sulphate is the major metabolite of dietary deoxynivalenol in eggs of laying hens

Previous studies reported very low carry-over of dietary deoxynivalenol (DON) into eggs of laying hens. However, recent studies showed that DON is extensively metabolised to DON-3-sulphate (DON-3S) in chickens. We therefore hypothesised that DON-3S might also be a major DON metabolite in eggs of laying hens fed with DON contaminated diet. The aim of the work was to develop, validate and apply an LC-MS/MS based method for determination of DON, deepoxy-DON (DOM), DON-3S, and DOM-3-sulphate (DOM-3S) in freeze-dried eggs of laying hens. Laying hens were allocated to three treatment groups (negative control (NC); DON low (3.8 mg/kg DON in feed); DON high (7.5 mg/kg DON in feed)) and eggs were collected in the 5th, 7th and 10th week of the trial. DON-3S was identified as the major DON metabolite in eggs for the first time with average concentrations in fresh eggs <0.74 ng/g in the NC, 4.4-6.4 ng/g in the DON low group and 7.9-9.7 ng/g in the DON high group. DON-3S was also the major DON metabolite in chicken plasma, with average concentrations of 6.8 +/- 4.1 and 10 +/- 7 ng/ml in the DON low and DON high group, respectively. Experiments with intestinal explants indicated that DON-3S is in part already formed in intestinal mucosa cells. Considering the carry-over factor of 0.001, the European guidance value of DON in poultry feed (5 mg/kg), the tolerable daily intake of DON (1 mu g/kg body weight and day) and the average egg consumption in Europe (0.5 egg/day/person), there is no significant health risk due to carry-over of DON or DON-3S into eggs, even if the per se non-toxic metabolite DON-3S might be hydrolysed back to free DON in the gut of the egg consumer.