On the effects of Fusarium toxin-contaminated wheat and the feed intake level on the metabolism and carry over of zearalenone in dairy cows

Abstract

The aim was to investigate the effect of feeding Fusarium toxin-contaminated wheat to dairy cows on the metabolism and carry over of zearalenone (ZON) and its metabolites at different feed intakes. Fourteen dairy cows equipped with rumen and duodenal fistulae were used. The experiment consisted of a control period in which the uncontaminated wheat was fed and a mycotoxin period in which the Fusarium toxin-contaminated wheat (8.21 mg deoxynivalenol (DON) and 91 µg ZON kg−1 dry matter (DM)) was replaced by the control wheat (0.25 mg DON kg−1 and 51 µg ZON kg−1 DM). The wheat portion of the concentrate fed daily amounted to 55% on a DM basis. The ration was completed with maize and grass silage (50:50), whereby the maize silage contained 62 µg ZON kg−1 DM. Feed intakes were adjusted to the current performance of the individual cows. The ZON metabolites α-zearalenol (α-ZOL) and β-zearalenol (β-ZOL) were recovered at the duodenum beside the parent toxin ZON. The recovery of ingested ZON as ZON plus α-ZOL plus β-ZOL at the duodenum ranged between 19 and 247%. The portion of ZON (ranging from 29 to 99%) of the ZON plus α-ZOL plus β-ZOL flow at the duodenum increased significantly with increasing ZON feed intake, whereas the portion of β-ZOL (up to 57%) decreased significantly. In contrast, portions of ZON in faeces (32–100%), α-ZOL (up to 39%) and β-ZOL (up to 43%) of ZON plus α-ZOL plus β-ZOL were independent of ZON intake. It seems that a lower retention time of the feed and the toxins in the rumen as an effect of the increased feed intake may limit the ruminal metabolization of ZON. The relatively steady recovery of ingested ZON as ZON, α-ZOL and β-ZOL in faeces at the different levels of ZON intake would suggest a further reduction of ZON by intestinal microorganisms. Furthermore, ZON and its metabolites in the milk were lower than the detection limits at daily ZON and DM intakes between 75 and 1125 µg and 5.6 and 20.5 kg day−1, respectively, and milk yields (fat corrected milk, FCM) between 10 and 42 kg day−1.