No carry over of unmetabolised deoxynivalenol in milk of dairy cows fed high concentrate proportions.

To examine the carry over of deoxynivalenol (DON) and its metabolite de-epoxy DON (DOM-1) in milk, lactating German Holstein cows (n = 13) were fed an isoenergetic total mixed ration in Period 1 with 50% concentrates and 5.3 mg DON/kg dry matter (DM) over 11 wk and were compared with control cows (n = 14). In Period 2 (18 wk), an elevated concentrate proportion was compared to a low concentrate ration by dividing the cows into four Groups (n = 8): Control-30 (30% concentrates), Myco-30 (30% concentrates, 4.4 mg DON/kg DM), Control-60 (60% concentrates) and Myco-60 (60% concentrates, 4.6 mg DON/kg DM). Taken both periods together, no unmetabolised DON was detected in milk samples using the HPLC-UV method. DOM-1 concentrations ranged between below the LOD and 3.2 microg/kg milk in mycotoxin fed cows, while control cows did not excrete any measurable amounts of DOM-1. Regarding the concentrate effects, the carry over of DON as DOM-1 in milk was negligible (between 0.0001 and 0.0011) but significantly higher in Group Myco-30 than in Group Myco-60. This effect may result from an altered bioavailability of DON from maize silage which made up a higher proportion of the daily ration.