Abstract
Zearalenone is a frequent contaminant of cereals and their by-products in regions with a temperate climate. This toxic molecule is produced naturally by Fusarium fungi in crops. The aim of this study was to determine the influence of low zearalenone doses (LOAEL, NOAEL and MABEL) on the intestinal microbiome of gilts on different days of exposure (days 7, 21 and 42). Intestinal contents were sampled from the duodenal cap, the third part of the duodenum, jejunum, caecum and the descending colon. The experiment was performed on 60 clinically healthy gilts with average BW of 14.5 ± 2 kg, divided into three experimental groups and a control group. Group ZEN5 animals were orally administered ZEN at 5 μg /kg BW, group ZEN10—10 μg ZEN/kg BW and group ZEN15—15 µg ZEN/kg BW. Five gilts from every group were euthanized on analytical dates 1, 2 and 3. Differences in the log values of microbial counts, mainly Escherichia coli and Enterococcus faecalis, were observed between the proximal and distal segments of the intestinal tract on different analytical dates as well as in the entire intestinal tract. Zearalenone affected the colony counts of intestinal microbiota rather than microbiome diversity, and its effect was greatest in groups ZEN10 and ZEN15. Microbial colony counts were similar in groups ZEN5 and C. In the analysed mycobiome, ZEN exerted a stimulatory effect on the log values of yeast and mould counts in all intestinal segments, in particular in the colon, and the greatest increase was noted on the first analytical date.
Highlights
Plant materials and their by-products are used in feed production, which increases the risk of mycotoxin poisoning in humans [1] and livestock, pigs in particular.Toxins 2019, 11, 296; doi:10.3390/toxins11050296 www.mdpi.com/journal/toxinsExposure to high doses of mycotoxins, including zearalenone (ZEN), has been well documented [2,3].extensive research conducted in the last decade indicates that health problems resulting from exposure to small doses of the parental compound [4,5,6] without modified mycotoxins [7] can be important
The following observations were made in the intestinal tract of animals exposed to low doses of ZEN in feed: (i)
Differences in the dose effect) and variability of microbiota, mainly in Escherichia coli and Enterococcus faecalis, were noted between the proximal and the distal segments of the intestinal tract; (ii) The smallest differences in microbial counts were observed in group ZEN5, in particular in proximal intestinal segments; (iii) The counts of coagulase-negative Staphylococci decreased significantly over time in the evaluated intestinal segments, and these microbiotas were not detected in the colon; (iv) In analyses of the variability of microbiota, Clostridium difficile colonies were not identified in group
Summary
Plant materials and their by-products are used in feed production, which increases the risk of mycotoxin (undesirable substance) poisoning in humans [1] and livestock, pigs in particular.Toxins 2019, 11, 296; doi:10.3390/toxins11050296 www.mdpi.com/journal/toxinsExposure to high doses of mycotoxins, including zearalenone (ZEN), has been well documented [2,3].extensive research conducted in the last decade indicates that health problems resulting from exposure to small doses of the parental compound [4,5,6] without modified mycotoxins [7] can be important. The minimal anticipated biological effect level (MABEL) dose enters into positive interactions with macroorganisms in different stages of their life cycle [13]. This observation contradicts the low-dose hypothesis, which plays an important role in relation to natural and hormonally active compounds [14] such as ZEN. The variations in the dose-response relationship induce differences in the interpretation of clinical symptoms and laboratory tests evaluating the risk of contamination with low doses of mycosteroids, such as ZEN, in plant materials [15]. An accurate determination of low mycotoxin doses in plant material would support a more reliable interpretation of the final effects [16]
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