Bioavailability of the Fusarium toxin deoxynivalenol (DON) from wheat straw and chaff in pigs.

Fusarium infections do not only affect the grain, but also the rest of the plant, which result in contamination of plants with the mycotoxin deoxynivalenol (DON). The bioavailability of DON may be influenced by the matrix due to the differences in nutrient composition between grain and straw, particularly the high fibre component in straw. The experiment was carried out by exposing 18 male castrated pigs (30-40 kg live weight) with a single dose of DON from wheat grain, straw and chaff in the diet. The courses of DON serum concentrations were evaluated using toxicokinetic methods. The absorption of DON was not influenced by the source of DON. The invasion half-life of DON from grain, straw and chaff amounted to 0.76, 0.77 and 0.48 h, respectively, and were not significantly different. The elimination of DON was also not affected by the DON source. The bioavailability of DON, calculated by the dose corrected area under the curve of the serum-DON-concentrations, amounted to 81.9, 87.3 and 109.8% for straw, grain and chaff, respectively, without significant differences. Thus, the uptake of DON from straw may contribute comparably to the overall exposure of animals.

Occurrence and distribution of 13 trichothecene toxins in naturally contaminated maize plants in Germany.

The objective of the present study was to monitor the occurrence and distribution of a spectrum of trichothecene toxins in different parts of maize plants. Therefore maize plants were sampled randomly from 13 fields in southwest Germany and the fractions kernels, cobs, husks, stalks, leaves and rudimentary ears were analyzed for eight A-type and five B-type trichothecenes. Each of the toxins was found in at least three of the total of 78 samples. The study revealed that both A-type and B-type trichothecenes may be present in all parts of the maize plant but may be unevenly distributed. For the contents of deoxynivalenol, 3- and 15-acetyldeoxynivalenol, nivalenol, scirpentriol, 15-monoacetoxyscirpenol, HT-2 and T-2 toxin significant differences (p < 0.05) were found between different parts of the maize plants whereas no significant differences were observed for fusarenon-X, 4,15-diacetoxyscirpenol, neosolaniol, T-2 triol and T-2 tetraol. Up to twelve toxins co-occurring in one sample were detected. As a group B-type trichothecenes dominated over A-type trichothecenes concerning incidences and levels. Contamination was strongest with rudimentary ears based on incidence and mean and maximum contents; mean contents with few exceptions tended towards a higher level than in other fractions with significant (p < 0.05) differences compared to leaves for seven toxins.

Effect of different storage conditions on the mycotoxin contamination of Fusarium culmorum-infected and non-infected wheat straw.

Mycotoxins are known to affect the health and performance of farm animals. In contrast to cereal grains, the straw is only rarely analysed for mycotoxins, although contaminated straw could additionally expose farm animals to mycotoxins. For this reason, two experiments were carried out to examine the effect of pre-harvest Fusarium infection (inoculation with F. culmorum) and different storage conditions on the mycotoxin concentrations in straw. In the first experiment, both the inoculated and the identically cultivated control straw were stored in rectangular bales either in a barn or outdoors for a time period of 32 weeks (farm-scale experiment). The second experiment was aimed to examine the mycotoxin concentrations during storage under controlled conditions in a temperature-controlled climatic chamber, with target dry matter contents of 86%, 82% and 78% using 1.5-l preservation jars (laboratory-scale experiment). While the concentration of deoxynivalenol and its derivates decreased in the farm-scale experiment when inoculated straw was stored outdoors, the zearalenone concentration increased within the same time period. The latter effect was also detected for the control straw. These opposite effects were probably caused by the massive water uptake during the outdoor storage. The only effect we observed in the laboratory-scale experiment with dry matter contents between 78% and 86% was a more pronounced decrease of the 3-acetyl-deoxynivalenol concentrations in the inoculated straw with increasing moisture contents.