FUSARIUM MOLDS AND ASSOCIATED MYCOTOXINS INFLUENCED BY CROPPING FACTORS

Recently published research from by Vogelgsang et al. (2019) in the European Journal of Agronomy, shows that the occurrence of Fusarium molds and mycotoxins are highly influenced by agronomic practices. Samples of wheat were collected and analyzed for molds and mycotoxins following several different cropping factors such as previous crop type, tillage method, plant resistance and fungicide use.

Regarding Fusarium graminearum and deoxynivalenol (DON), the occurrence and concentration of this mold and mycotoxin were increased in wheat grain samples from fields that had previous crop maize, reduced tillage, poor Fusarium head blight (FHB) resistance and the use of strobilurin-based fungicides. The use of other previous crop types, as well as ploughing of fields, reduced DON content.


The presence of zearalenone (ZEA) showed a similar pattern to DON.


In contrast to DON and ZEA presence, the occurrence of the mold F. poae and nivalenol was associated with wheat collected from ploughed fields and the previous crop of canola.


The data collected over this 8 year period suggests that there can be different ecological niches for different molds and mycotoxins. This was demonstrated by the results found for different Fusarium molds and mycotoxins. For DON and ZEA, risk is greatly increased in wheat with corn is a previous crop along with reduced tillage whereas soybeans as a previous crop may lower risk. In contrast, reduced nivalenol was associated with reduced tillage practice. As a result, different agronomic practices may influence mycotoxin type and concentration detected in crops.

Reducing the risk of aflatoxin in broiler chickens

Aflatoxins, produced by Aspergillus species of molds, are carcinogenic mycotoxins that can cause adverse effects to organ health, immunity and performance in animals. To reduce the risk of aflatoxins, dietary feed additives can be used as a practical, cost-effective method. In recently published research by Saki et al. (2018) in the Journal of Livestock Science and Technology, investigated the effect of aflatoxin contaminated diet on broilers with or without the use of the glucomannan-containing yeast additive Mycosorb (Alltech, Inc).

In this research, broilers showed a decrease in feed intake and growth rate when consuming diets containing 1 mg/kg aflatoxin. However, birds consuming the contaminated diet with 0.25% Mycosorb had significantly improved feed intake by 3.2% and weight gain by 5.2%. Broiler index (daily weight gain (g) x survival (%) x FCR) was also significantly increased in birds consuming Mycosorb during the mycotoxin challenge.


Consumption of aflatoxin by broilers does not only impact performance but may also have a presence in edible tissues including liver and breast muscle tissue. Interestingly, the ingestion of aflatoxin at 1 mg/kg resulted in significantly increased levels of aflatoxin contamination in liver and breast muscle at both 21 and 42 days of the trial. When Mycosorb was included into the contaminated ration, there were significant reduced levels of aflatoxin in both liver and breast muscle tissue at days 21 and 42.


Overall, this data suggests that aflatoxins can cause negative effects on broilers, while the inclusion of Mycosorb into the ration can help to ameliorate these effects.

Combating different mycotoxins takes different strategies

There are hundreds of different mycotoxin compounds, but aflatoxins (AF) and T-2 toxin are certainly ones that pose significant risk to poultry. This research by Girish and Devegowda (2006) from Asian-Australasian Journal of Animal Sciences, showed how these two mycotoxins impact commercial broilers and how different mitigation strategies may be needed depending on the mycotoxin present.

In this research, broilers were fed for 35 days diets containing 0 or 2 mg/kg AF, 0 or 1 mg/kg T-2, AF and T2 combined, 0 or 1 kg/ton Mycosorb (Alltech, Inc) and 0 or 10 kg/ton hydrated sodium calcium aluminosilicate (HSCAS). Results showed birds consuming either mycotoxin had significantly reduced body weights while the combination of the two mycotoxins caused an additive effect on gain.


Clay materials such as HSCAS have been shown to have benefits in binding to highly charged molecules such as AF. T-2 toxin however has a different structure and lacks the attractive charge. As a result, as was demonstrated in this current research, HSCAS supplementation improved the performance of broilers only in the AF fed groups. The inclusion of 10 kg/ton of HSCAS did not afford any protection against the toxicity of T-2 toxin. Conversely, the addition of Mycosorb at 1 kg/ton to the diets containing AF and/or T2 toxin resulted in broilers with significantly improved performance.


Additionally, antibody titers against Newcastle Disease and Infectious Bursal Disease were significantly reduced in all mycotoxin groups. This suggests suppression of the immune system and potential vaccine failure. To combat this challenge, it was observed that the inclusion of Mycosorb significantly improved antibody titers during mycotoxicosis caused by both AF and T-2 toxin, whereas HSCAS only improved titers in the AF challenged birds.


Overall, this data suggests that there can be additive or potentially synergistic interactions between aflatoxins and
T-2 toxin, and that these can cause negative effects on broilers. Birds fed the glucomannan based yeast product, Mycosorb, have improved performance, organ health and immunity during both AF and T-2 challenges whereas HSCAS was only effective during an AF challenge.

Low doses of type B trichothecenes can have synergistic impacts on intestinal cells

There are hundreds of different mycotoxin compounds, but aflatoxins (AF) and T-2 toxin are certainly ones that pose significant risk to poultry. This research by Girish and Devegowda (2006) from Asian-Australasian Journal of Animal Sciences, showed how these two mycotoxins impact commercial broilers and how different mitigation strategies may be needed depending on the mycotoxin present.

The type B trichothecenes are a group of mycotoxins produced by Fusarium fungi. Deoxynivalenol (DON) is likely the most prevalent and well known of this group, but there are several other members which may play an important role in toxicity to animals. Additionally, the combination of these different type B trichothecenes may increase the risk. Research conducted by Alassane-Kpembi et al. (2013) published in the journal of Toxicology and Applied Pharmacology, investigated the effects and interactions of five different type B trichothecene mycotoxins on intestinal epithelial cells. The five mycotoxins were: DON, 3-acetyl-deoxynivalenol (3-ADON), 15-acetyl-deoxynivalenol (15-ADON), nivalenol (NIV) and fusarenon-X (FX).


Following exposure of the intestinal epithelial cells to the five type B trichothecenes, it was determined that all mycotoxins impacted the proliferation of the enterocytes in a dose-dependent manner. Individually, the classification of these mycotoxins in their order of toxicity is 3-ADON has lower toxicity than 15-ADON which is about equal in toxicity to DON which is less than NIV which has lesser toxicity than FX (3-ADON < 15-ADON≈DON < NIV < FX).


Combinations of two or three of these mycotoxins also showed dose-dependent effects on enterocyte proliferation. Interestingly, at lower mycotoxin concentrations (cytotoxicity of 10 to 40%), most interactions were synergistic. At higher mycotoxin concentrations (cytotoxicity of about 50%), the combinations of mycotoxins had additive effects.


Overall, this data suggests that type B trichothecenes do influence the intestinal epithelial cells. Furthermore, it was determined that lower levels of these mycotoxins in combination may in fact be more toxic than mycotoxins alone. Type B trichothecenes are one of the most commonly detected mycotoxin groups in feedstuffs, and thus synergistic interactions of these compounds should be considered.­

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