Nutritionist > Equine

Mycotoxin adsorbents and binders
As we know mycotoxins are usually found in combinations in compound horse feeds. A broad substrate binding capacity will ensure at least some fraction of all the mycotoxins will be rendered non-bioavailable and the bioavailable mycotoxins will be below the threshold of biological activity. Broad substrate binding capacity of a binding agent will also minimise the potential for toxicological synergy between mycotoxins.

Speciality feed additives, known as mycotoxin adsorbents or binding agents are the most common approach to prevent and treat mycotoxicosis in horses. It is believed that the agents bind to the mycotoxin preventing them from being absorbed. The mycotoxins and the binding agent are excreted in the manure.

The efficacy of glucomannan-containing yeast products as mycotoxin adsorbents in feeds has been investigated globally with several studies with all animals [Click here to see in vivo research]. Research conducted in France at the National Institute for Agricultural Research (INRA) identified four Saccharomyes cerevisiae yeast strains that differed greatly in their glucan/mannan ratio. It was found that large differences existed in adsorptive capacity between the yeast strains with the amount of mycotoxin adsorbed strongly related to the beta-D-glucan content. This research confirms earlier work carried out by Alltech which led to the selection of a yeast strain high in insoluble beta-D-glucan content for the design and production of glucomannan-containing yeast product. (Yiannikouris et al., 2004). Advanced molecular techniques were used to elucidate the spatial conformation and molecular sites of interaction between zearalenone and glucomannan-containing yeast product. Molecular modelling was used to locate the interaction sites. Both hydrogen bonds and van der Waal's stacking interactions were identified as key interactions between mycotoxins and glucomannan-containing yeast product (Figure A)

Figure A
(Yiannikouris et al., 2004; Biomacromolecules, 5:2176-2185)

Research with Mycosorb® has shown that using mycosorb reduced the negative effects of Fusarium mycotoxins in horses (Raymond et al., 2003). Nine mature mares were fed for 3 weeks, a concentrate and 5kg hay daily. The concentrate was either the control or contaminated grains or contaminated grains plus 0.2% Mycosorb. Horses fed Fusarium- mycotoxin contaminated feed showed a reduction in feed consumption, which was partially prevented by feeding Mycosorb. In addition the increase in serum GGT (a liver enzyme), which signifies liver damage, was seen in the mares fed contaminated grains but was prevented with the inclusion of Mycosorb.

Mycotoxin adsorbents offer an attractive short-term solution to the challenge of mycotoxin-contaminated animal feeds. The only complete solution to the mycotoxin challenge will be the long-term goal of eliminating mycotoxins from the foodstuffs through improved quality control based on better analytical techniques coupled with genetic advances in plant resistance to fungal infestation.