During a period of one and a half year, 384 feed samples and 330 serum samples were analysed for ochratoxin A. In the same time, 391 feed samples and 234 serum samples were analysed for zearalenone. On average, 17,7 % (n=68) of the feed samples and 55,2 % (n=182) of the serum samples were ochratoxin A positiv. Zearalenone was found in 74,4 % (n=291) of the feed samples and in 6,0 % (n=14) of the serum samples. Those results showed that an individual determination of the recovery rate for each feed sample is very important for the real value. If ochratoxin A was traced in the feed, it can also be found in the sera of pigs fed with this feed. Due to the different detectibility limits with 0,1 ppb in sera and 1 ppb in feed, even smallest amounts can be analysed in the blood serum. If zearalenone intoxication is suspected, the feedstuff analysis is to prefer because the half time period of zearalenone in blood is very short. In this study different influences on the intoxication levels could be shown:
1. Seasonality: The frequency of intoxication increases with the time of feed storage. Because of the varing climatic circumstances, the values differ from year to year. 2. Farm type: More frequently, the serum samples of fattening herds were more often ochratoxin A positiv than the samples of sow herds. Zearalenone was found more frequently in feed of fattening herds than in sow herds. 3. Storing type: Compared to indoor silo or storage on the floor, the ochratoxin A contamination of the feed in outdoor silos was lower. The highest ochratoxin A-contamination rate was found by storage in sacks or on the floor. The highest zearalenone contamination rate was found in feed stored in outdoor silo.
4. Feedstuff derivation: In comparison to pigs which got home mixed feed, pigs supplied with purchased feed showed serologically more ochratoxin A positiv results. There was no different in the zearalenone contamination of purchased feed and home mixed feed.
5. Straw bedding: The analysis of straw often showed high values of both mycotoxins. Therefore, an analysis of the straw seams to be necessary if an intoxication with mycotoxins is suspected. This study demonstrates that samples accidentially taken for the field study are more frequently ochratoxin A contaminated than toxin-suspected samples. It showed further more, that in toxin-suspected feed samples zearalenone was more frequently detected than in the samples of the field study. The results demonstrate, that the clinical diagnosis of an ochratoxin A intoxication is more difficult than the diagnosis of the zearalenone syndrome.
