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What are Mycotoxins and how can we reduce their impact?

February 22, 2022

What are Mycotoxins and how can we reduce their impact?

Mycotoxins are secondary metabolites produced by certain types of fungi (moulds), which increase in the presence of oxygen in the hot, humid months of the year. These fungi produce mycotoxins under certain conditions, which can be harmful to animal health and productivity. It’s important to note that not all fungi produce mycotoxins, and the presence of fungi does not mean that mycotoxins are present. Conversely, the absence of fungi does not imply that no mycotoxins are present.

There are several hundred mycotoxins, but those that present the most risk to animal health include the following:

Mycotoxins are secondary metabolites produced by certain types of fungi (moulds), which increase in the presence of oxygen in the hot, humid months of the year. These fungi produce mycotoxins under certain conditions, which can be harmful to animal health and productivity. It’s important to note that not all fungi produce mycotoxins, and the presence of fungi does not mean that mycotoxins are present. Conversely, the absence of fungi does not imply that no mycotoxins are present.

There are several hundred mycotoxins, but those that present the most risk to animal health include the following:

Fumonisins are produced by Fusarium monoliforme, with Fumonisin B1 being the most common mycotoxin. These are most commonly found in maize-based products, although they have also been reported in forage grass in NZ. Exposure to this mycotoxin may result in liver damage and impairment of the immune system.

Trichothecenes – these have mainly been derived from Fusarium spp. and include T-2 toxins, deoxynivalenol (DON) and nivalenol (NIV). These are often found in grains. These mycotoxins affect rapidly dividing cells, like those found in the gastrointestinal tract, affecting nutrient absorption. These mycotoxins are also known immunosuppressants, so they affect the ability of the animal to provide an immune response to disease challenge

Ochratoxins – these are derived predominantly from Aspergillus and Penicillium spp. Ochratoxin A is the main mycotoxin found in grains. Ochratoxin mainly affects the kidney resulting in poor electrolyte balance and increased water excretion.

Aflatoxins – these are mycotoxins produced in storage by Aspergillus spp. and include Aflatoxin B1, B2, G1 and G2. Aflatoxin B1 is converted into Aflatoxin M1 in milk. The residues of this mycotoxin are strictly controlled via the regulatory systems with milk processors. The target organ for aflatoxin is the liver. The major concern with aflatoxins is the carcinogenic effect in humans from eating meat or milk high in aflatoxin.

Zearalenone – is produced by Fusarium spp. and has potent estrogenic properties. As a result, it can induce oestrus causing abortions.

Ergot alkaloids are produced by Claviceps spp. The predominant mycotoxin is ergotamine—these cause vasoconstrictions resulting in decreased blood flow to the extremities.

A symptom often seen is animals overheating and seeking shade or cooling (water).

Mycotoxin producing fungi are found primarily on plant products while the plant is growing (grass, wheat, barley, maize and oilseeds like soya, canola, copra and PKE) but also following harvest and during storage (grain and silages). An example is ryegrass in summer, which is the perfect environment for fungi growth at the base of the sward. The ryegrass endophytes (fungi) produce a mycotoxin called Lolitrem B. When ingested, this results in a condition called “ryegrass staggers” in ruminants and horses often characterised by tremors, flighty animals, heats stress, lower fertility and even death. A further example is aflatoxin, which can develop during grain storage when conditions in the storage equipment are too hot and humid. Aflatoxin is a human carcinogen and is well known to cause residues in milk, so milk processors strictly monitor it. A common issue we see is mould spoilage on silage.

It’s important that affected feeds aren’t fed to animals and that preventative silage management strategies are used (for example proven oxygen barrier covers like Silostop®) to minimise the top layer of mould on silage stacks and good fermentation inoculants (like Sil-All® and MAGNIVA ® Platinum) to reduce pH and minimise aerobic spoilage and heating at feedout.

The most susceptible animals to mycotoxin damage are monogastric animals (pigs and poultry). These sectors have long recognised the effects these mycotoxins have on animal health and performance and regularly monitor grain during storage and make regular preventative use of mycotoxin binders in high risk animals. As an example, the Zearalenone mycotoxin is well known to cause abortions in pigs which is why mycotoxin binders are routinely used in sows. For many years, nutritionists believed the normal enzymes in the rumen could de-activate the mycotoxins ingested, but with more relevant research we have come to realise that this is not always the case and ruminant animals do respond to mycotoxin binders. Many nutritionists and their clients have also realised that prevention is better than cure, especially in breeding animals.

The research around the use of mycotoxin binders over the last 30 years has shown how both monogastric and ruminant animals respond to appropriate application of mycotoxin binders. There are two approaches to “binding” mycotoxins. These include “Polar Binding” using products like clinoptilolite (clay), which have a high cation exchange capacity and can use their charge to attach to certain mycotoxins, including aflatoxins, fumonisins, lolitrem-B and ergot alkaloids.

The other approach is to use yeast extracts containing mannan oligosaccharides, particularly B-glucans, which physically absorb the mycotoxins via van de Waal’s interactions and hydrogen bonding (Ionic and Covalent Bonding). This methodology is useful for mycotoxins like zearalenone.

Therefore, it is important to know what the main target mycotoxins are that we are trying to bind when selecting a mycotoxin binder product. Since it is infrequent that only one mycotoxin is present in a feed source, it is prudent to manage risk; a mycotoxin binder should contain both a clinoptilolite (clay) a yeast extract high in B-Glucan.

Finally, it is important to know that all mycotoxin binders in NZ need to be registered with MPI via the Animal Compounds and Veterinary Medicines (ACVM) process to ensure a valid label claim can be made to bind mycotoxins.

In NZ, Nutritech distributes the ACVM registered mycotoxin binder called Fusion® DYAD*, a combination of clinoptilolite and a mannan oligosaccharide high in B-glucan. This product has shown to be effective in binding a range of mycotoxins:

Please get in touch with your local Nutritech Area Manager for further information.

* Fusion® DYAD is registered pursuant to the ACVM Act 1997, No. A011062

Fusion® DYAD is an effective broad spectrum, mycotoxin management tool.

Most mycotoxin testings are carried out using individual toxins. However, in reality, multiple mycotoxins co-exist in nature and will be present in animal feed.

Fusion® DYAD was included at 0.1% and binding was tested for each mycotoxin individually. A second test was then carried out with all the mycotoxins included together and the resultant binding ability measured in comparison with the initial test. The level of toxin in all experiments was set at 1ppm.

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