Common Solutions for Mycotoxins

Clay and Yeast Binders

A majority of binder products are routinely tested in vitro; a known amount of purified toxin is dissolved in a volume of aqueous methanol and this solution is tested for toxin concentration. Then, some amount of the binder is added and mixture stirred for some minutes; the mixture is then filtered to remove the binder, and the solution is retested for toxin. The difference between the before and after tests is advertized as the toxin binding capacity of that binder.

In the EU, where more stringent controls over mycotoxin contamination are in force, analysts were concerned that the presence of binder in a feed or ingredient would mask mycotoxins from discovery during regulatory testing of such materials. Recently, a number of labs have tested this theory.

Kolossova et al. [2009. Evaluation of the effect of mycotoxin binders in animal feed on the analytical performance of standardized methods for the determination of mycotoxin in feed. European Commission/Joint Research Centre Technical Report # JRC54375. 46pp] included 5 yeast-based binders, 10 clay or aluminosilicate type, and 5 additional such as lignin-cellulose and some mineral+acid products. In the figure above, the two toxins with the most stringent regulatory standards were tested against each product. Adapted from Kolossova et al., the graph shows the response obtained by the best and worst clay- and yeast-based products. What is most unusual is that the best clay product for DON removed about 17% of that toxin while the best clay product for AF only removed 11% of the AF (both were aluminosilicate products)! This is very atypical of that type of binder. Note also that the best yeast products removed less than half as much AF and one fourth as much DON as the clay counterparts. Finally, the “worst” clays did as well as the “best” yeasts while the “worst” yeast did virtually nothing. Keep in mind that all of the products tested were on the market, recognized commercial offerings.

That same group repeated the tests for a series of additional mycotoxins. One major difference was that data were averaged by product type rather than reported for individual binding agents. So, graphical comparisons as in the above figure are not possible. However, for ochratoxin A, fumonisins, zearalenone, and T-2 toxin, binders never removed more than 3% and for most toxins had no effect at all. The bottom line is, once again, binders, even when given the advantage of an in vitro test system, rarely deliver on the spectacular promises made in the marketplace. The facts are that binding capacities under ideal conditions are poor to non-existent for the majority of common toxins to which domestic species are exposed every day. And most of the binders come with a very serious down-side. As the EU research team summarized it, clay binders can be contaminated with heavy metals and dioxins (harm to animals and humans which consume them!) and are known to tie up vitamin E, various minerals, lysine, and other micronutrients from the ration. And yeasts are known to operate via relative weak ionic/hydrogen/van der Waals bonds which can be reversed easily under physiological conditions. So although “cheap” on a unit basis, they are immensely expensive in terms of failure to perform as needed and bringing high risk to the farm animals that are made to consume them.

Takagi et al. (2011). Measurement of urinary zearalenone concentraations for monitoring natural feed contamination in cattle herds: on-farm trials. J. Anim. Sci. 89:287-296.

The results look promising at first glance; however, problematic in this study was the fact that Zea was not measured in the feed at any time. Cows, whether on experiment or not, in conventional TMR feeding are not all consuming the same amount each day nor is the exposure the same from day to day. So without knowing how much Zea was consumed by these cows, the interpretation of urinary excretion data is highly equivocal. By the way, the alpha-zeranol is a metabolite formed by microbial conversion of Zea in the rumen; it is 3-4 times more estrogenic than the parent Zea!

BOTTOM LINE: Binders are an inappropriate choice most of the time for an approach to meeting a mixed mycotoxin challenge. However, effective solutions for mycotoxin challenges do exist. Contact us for further information. 

Prepared for Agrarian Solutions February 19, 2012

John A. Doerr, Ph.D., Vice President, Science & Technology