The contamination of animal feed with multiple toxins is an on-going issue of both economic as well as health. Toxic substances such as mycotoxins, residues of pesticides, dioxins, heavy metals, veterinary medicines and aromatic hydrocarbons are almost ubiquitous in the environment. These toxins are metabolized before and after absorption into the animal bloodstream through the intestinal tract and produce a wide range of injurious effects in animals and foodborne hazards to humans. The accrual of mycotoxins in foods and feeds make significant effect health threats to humans and animals, as they are responsible for many different toxicities effects of carcinogenicity, mutagenicity and, tissue damages and suppress the function of liver and kidney, and nervous disorders. Some mycotoxins are highly affected and make an imbalance of immunological activities, and can thus reduce resistance to infectious disease. Due to the significant impact of toxin make economic losses are associated with human health, animal productivity in both domestic and international trade. This review discusses information on suitable toxin binders to control all above listed toxic effects on animals and human beings.
Handling and minimizing the impact of Multitoxins by Toxin binder
To minimize and eradicate the negative effects of multi-toxins in farm animals, various methods have been followed including physical, chemical, and biological degradation of multi-toxins. However, the detoxification of feed contaminated with various toxins is restricted because of the problems associated with health and safety issues, possibly loses in the nutritional quality of treated feeds coupled with limited efficacy and cost implications. An alternative and popular approach to decreasing toxicity in animals is the use of toxin binders as feed additives that can reduce the contamination of feed by various toxins and suppressor reduce their absorption, promote excretion or alter their mode of action and minimize the hazardous impacts. The addition of feed toxin binders are the prevalent strategy widely used by feed millers and farmers, due to its practical and economic feasibility.
Desirable Characteristics of a Toxin Binder
A binder must be effective at sequestering multi-toxins in some cases; it may be specific to one toxin and in others to bind multiple toxins. A binder should significantly prevent animal toxicity at the same time should not be serious adverse effects on the animal and their foods or at least detrimental effects should not compensate for the benefits. It should be cost-effective, animals and its product should be free from residues of multi-toxins. Multi- toxins in feeds should not be masked. It must be usable in commercial feed manufacturing and its efficacy should be verifiable. The Physico-chemical properties of toxin binders such as surface area, pore size, total charge, charge distribution, iodine number, methylene blue adsorption value (MBA value) and pH are the most important key factors for its toxin binding effectiveness. On the other hand, the properties of multi-toxins such as polarity, solubility, form and size of the toxins to be adsorbed and the presence of ionized compounds in the environment are other effective factors. The binding efficacy of toxin by toxin binders are highly influence by nutritional values of feed, an example fiber content will increase the mycotoxins affinity towards adsorbent, at the same time using adsorbents need to be critically evaluated about their safety because the toxin binders added to the feeds are thought to make non-specific bindings, which make nutritional losses or deficiency to the animals.
Types of Toxin Binders
Aluminosilicates - Bentonite, Zeolite, Montmorillonite, and Sepiolite
Activated Carbon
Glucomannan
Chlorophylls
Probiotics
Efficacy of Different Binders on Multi-toxins
Aluminosilicates
Clays are natural chemically made of silicates or Aluminosilicates with the unique properties of adsorbents. They include a large range of silicates such as Hydrated Sodium Calcium Aluminosilicates (HSCAS), phyllosilicates (Montmorillonite or Magnesium Hydrated HSCAS), Bentonite and Zeolite (two are clays of volcanic origin). HSCAS binders have the property of adsorbing inorganic substances either on their external surfaces or within their inter-laminar spaces, by the interaction with/or substitution of the exchange educations within these spaces. By elementary, electrical charges mycotoxins are adsorbed into the clay surface porous. Thus, HSCAS has more affinity on Aflatoxins, while it has included in animal feed at 0.2 - 0.5% of inclusion to effectively adsorb Aflatoxins and prevent Aflatoxicosis conditions. However, data shows HSCAS fails in the adsorption of other mycotoxins (not a multi-toxin binder); Zeolites are hydrated aluminosilicates made from interlinked tetrahedrons of Silica (SiO4) and Alumina (AlO4) as the two fundamental building blocks with the metal atom at the center of each tetrahedron. Zeolites have a high affinity for the adsorption of multi-toxin (Ochratoxin A, Zearalenone and residues of other chemical components).
Bentonites are originating from volcanic ash and containing primarily Montmorillonite; extensively using many different industries like the beer industry as a clarifying agent, discoloring and deodorizer of oils. Adsorption depends on the interchangeable cations (Na+, K+, Ca++, Mg++) present in the layers. Bentonites adsorb Aflatoxins, Ochratoxins and Zearalenone.
Activated Carbon
Activated carbon is a very porous non-soluble powder with a high surface area from the range of 500-3500 m2/g. Since the 19th century Activated Carbon has been used as an antivenin against poisoning. Therefore, it might also inactivate mycotoxins. In aqueous solution, it can effectively adsorb most of the mycotoxins such as Aflatoxins, Ochratoxins, Fumonisin, Zearalenone and Trichothecenes through hydrogen bonding. Hence, it efficiently acts against mycotoxicosis. Activated carbon is an unspecific adsorbent and, hence, it adsorbs essential nutrients particularly when their concentrations in the feed are much higher compared to the concentration of Multitoxins.
Yeast and Bacterial Cell Wall
Yeast cell walls are composed of polysaccharides and glycoproteins. Addition of yeast cell walls into the contaminated animal feeds eliminates the harmful effects of mycotoxins through the chemical interactions on the toxins. Yeast cell walls are efficient in binding a broad range of mycotoxins such as Aflatoxins, Zearalenone, Fumonisin and T-2 toxins. Yeast cell wall usually adsorbs toxins in the mechanism of Hydrogen and van der Waals bonds, ionic, or hydrophobic interactions. Bacterial cell walls also have the potential to bind AF, but limited research has been conducted and some researches are on-going.
Conclusion
The application of a single adsorbent is efficient against limited toxins. However, the addition of different adsorbents or very promising derivatives adsorbents to animal feed provides versatile tools for preventing mycotoxicosis. But the selection and formulation of multi-toxin binder is a scientific art to give a complete broad range of toxins sequesters. With a thorough understanding of toxins, their source and behaviours in animal and interaction with toxin binders are the only solution to minimize the toxin's effects and economic sufferers.
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