Some years are certainly worse than others for mycotoxins. When mycotoxins are expected to be the “tipping point” that sets off a health issues it is helpful to have a laboratory test that can confirm the levels of the suspect mycotoxin in the feed. Unfortunately, diagnosing mycotoxin levels is not usually a simple process. High positive test result for a mycotoxin will certainly confirm a mycotoxin problem. The bigger problem is false negative results. Finding the right subsample can be hit or miss when there are “pockets” of mycotoxin in feed. Another cause of false negatives is the presence “masked mycotoxins” in feed.
Masked or modified forms of Zearalenone (ZEN) are alternate forms of ZEN. After ingestion, they can be cleaved by gastric acid, small intestinal enzymes or large intestinal microbial activity into the parental form. Modified mycotoxins can themselves possess estrogenic potential which sometimes exceeds even that of the parental ZEN. They are not routinely monitored nor regulated. Biomonitoring of selected metabolites in body fluids can be used as quantitative indicators of exposure. Rather than looking for a “needle in a haystack” in the feed the total effect of exposure to both the parent mycotoxin and its masked modified forms is evaluated by measuring them in bodily fluid after ingestion and absorption.EU researchers wanted to better understand the toxicity and bioavailability of Zearalenone (ZEN) and its common modified forms including α-zearalenol (α-ZEL), β-zearalenol (β-ZEL), zearalenone-14-glucoside (ZEN14G) and zearalenone-14-sulfate (ZEN14S). After pigs were exposed by means of intravenous and oral administration of ZEN and its modified forms the systemic blood plasma concentrations of the toxins and their metabolites were quantified.
The researchers found the following:
- ZEN14G and ZEN14S were completely hydrolysed to ZEN.
- All administered compounds demonstrated high oral bioavailability.
Take Home Message
Zearalenone and the modified Zearalenone forms such as α-ZEL, β-ZEL, ZEN14G and ZEN14S work together to contribute to overall Zearalenone systemic toxicity in pigs.
When faced with a lot of red swollen vulvas and teats in prepubertal growing pigs in the face of low or negative Zearalenone diagnostics the problem may be related to masked or modified forms.
Sometimes the pigs are better able to tell us what the problem is rather than the diagnostics.
Submitted by Clint Lichty, DVM
Ref: Catteuw A, Broekaert N, De Baere S, Lauwers M, Gasthuys E, Huybrechts B, Callebaut A, Ivanova L, Uhlig S, De Boevre M, De Saeger S, Gehring R, Devreese M, Croubels S. Insights into in vivo absolute oral bioavailability, biotransformation and toxicokinetics of zearalenone, α-zearalenol, β-zearalenol, zearalenone-14-glucoside and zearalenone-14-sulfate in pigs. J Agric Food Chem. 2019 Feb 26. doi: 10.1021/acs.jafc.8b05838. [Epub ahead of print]