Agriculture Business Week

We will focus on the control and prevention of feedborne mycotoxins in livestock and poultry. Mycotoxin expert, Dr Trevor K. Smith, professor. from the Department of Animal Science, Ontario Agricultural College of Guelph, Ontario, Canada, and external consultant of Alltech, Kentucky, USA, will answer some of the frequently asked questions (FAQs) on the proper detoxification of those profit-robbing mycotoxins:

Question: What are mycotoxin binders? What are their salient features?

Answer: Mycotoxin binders are large molecular weight polymers that, when added to feed, are capable of forming irreversible complexes with mycotoxin molecules in the intestinal lumen. Such complexes are not digestible, pass down the digestive tract and are excreted in feces.
Q: What’s the net effect of feed detoxification using binders?
A: The net effect is the reduced dosage of absorbed toxin to the point that it is below the biological threshold. This allows contaminated feed to be given with minimal losses in performance.

Q: What’s the challenge in the mycotoxin control research?
A: The challenge is to identify compounds that can effectively bind a mixture of mycotoxins with widely varying molecular structures and polarities. The binder must also be effective at low levels of inclusion since these non-nutritive additives are diluents that will reduce the nutrient density of the diet. Activated charcoal is an example of a toxin binder that has been widely used in veterinary medicine to treat accidental acute poisonings.

Q: What are the limitations of silicabased inorganic polymers?
A: Mycotoxin binders can be silicabased inorganic polymers or carbon-based organic polymers. The inorganic polymers currently on the market include natural clay products (HSCAS, bentonites, zeolites) as well as synthetic polymers. The advantage of the clay-based products is their low price. Unfortunately these products also offer low specificity and must be used at a relatively high level of inclusion (5 kg/ton of feed) to be effective. This is the case for both bentonine and spent canola oil bleaching clays when overcoming T-2 toxicosis.

Synthetic inorganic polymers have usually been designed to effectively bind one specific mycotoxin, the aflatoxin. Such specific products are, therefore, much less effective against a mixture of mycotoxins of varying molecular weight and polarity. Synthetic products are inevitably more expensive than naturally-produced materials.

Q: How about organic binders? How effective are they in sequestering mycotoxins?
A: Organic toxin binders are derived from plant or microbial fibers. Studies in our laboratory indicated that lignin-rich alfalfa fiber was quite effective at overcoming the toxicity of T-2 toxin and zearalenone. An advantage of using organic fibers as mycotoxin binders such as dehydrated alfalfa meal is that they have some dietary energy and protein content and do not act as dietary diluents in the manner of inorganic polymers. Alfalfa fiber, however, like clay-based products, is effective at only high levels of dietary inclusion. This makes such materials impractical when added to livestock and poultry diets.

Q: What’s the latest innovation in mycotoxin binders?
A: An innovation in mycotoxin binders is the concept of organic polymers derived from yeast cell wall. This material has a high surface area and enough specificity to allow effective mycotoxin binding at a low level of dietary inclusion.

A good example of such organic polymers is MTB-l00 (Mycosorb), a unique formulation from Alltech, USA containing complex components extracted from the cell wall of the yeast Saccharomyces cerevisiae 1026. Due to its porous nature, MTB-100 provides the highest possible surface area (1 gram of the product = 20 m2) at the lowest possible rate of inclusion (500 grams/ton of feed).

Q: Aside from its low inclusion rate and vast surface area, what are MTB-100’s other advantages?
A: Unlike bentonites or zeolites. MTB-100 does not bind other nutrients or drugs. Its efficacy is unaffected by high temperature brought about by pelleting, expansion or extrusion. Changes in pH during digestion do not alter product effectiveness. It has no withdrawal period. So far, it is the only patented yeast-based binder in its category.

Part 3 of the article will present a series of experiments -conducted to determine the effectiveness of yeast cell wall polymers in overcoming Fusarium mycotoxicoses in broilers and swine.