Global state of mycotoxins

By Karin Nährer & Paula Kovalsky,  product managers Mycofix®, Biomin, Austria


Mycotoxin-producing fungi can colonise all kinds of agricultural commodities. Some mycotoxins, such as deoxynivalenol, are even used by the fungus to spread within the host plant. For example, DON has been shown to be a virulence factor needed for Fusarium to spread in wheat. The growth and development of the fungus, as well as the production of mycotoxins, depend on a series of factors such as temperature, humidity and insect attacks. However, plant-related factors, such as general stress conditions and susceptibility, also play an important role in the mycotoxin patterns observed in each plant.
Animal nutrition company Biomin tested 4,218 samples from more than 40 commodities intended for animal feed. A total of over 16,300 single analyses were carried out and provide a representative worldwide sampling. In this article we look at the incidence of different mycotoxins (Alfatoxins (Afla), deoxynivalenol (DON), fumonisins (FUM), zearalenone (ZON) and ochratoxin A (OTA)) in different commodities.

Shifts from 2012

Compared to 2012, the number of samples tested positive for Afla increased by 5% in 2013 to 30%.
However, the average of these positive samples remained almost the same as the previous year (31 ppb). A concentration of 31 ppb Afla poses a medium risk for swine and poultry (breeders, turkeys and ducks). There is a decrease in the number of positive samples and average concentrations for ZEN and DON compared to the survey in 2012. The maximum value of ZEN was detected in a Chinese corn sample at 5,324 ppb – a concentration level that would lead to adverse effects in all kinds of livestock animals. 
Despite the reduction in average DON concentrations to 777 ppb, this level still poses a high risk for piglets, which show the highest sensitivity to the toxin. FUM levels have remained similar to 2012 at about 1,400 ppb. Although the number of positive OTA samples declined to 23%, the average concentrations increased twofold to 10 ppb, which can pose a medium risk for some poultry species, such as layers, breeder, ducks and turkeys.

High levels in corn

Some of the most important commodities intended for animal feed around the globe are corn and wheat, and are therefore the most extensively tested commodities. African corn samples showed the highest incidence of Afla (50%), DON (80%), FUM (94%) and OTA (44%) compared to corn samples from all other regions. Asian corn samples showed the highest incidence of ZEN (45%) and also the highest average concentrations of ZEN (244 ppb) and DON (592 ppb).
North American corn samples contained the highest average concentrations of Afla (61 ppb). In South American corn samples, not only the incidence of FUM was second highest among all regions (93%) but also these samples contained the highest average level observed (3,052 ppb). With an incidence of 67%, DON is the most common mycotoxin in wheat worldwide. The average DON concentration in wheat is 1,217 ppb, which is more than twice the amount that was found in Asian corn samples.

Risky corn by-products

Whole grain corn contained the highest average value for the sum of aflatoxins (61 ppb). At 61 ppb of total aflatoxins, swine and poultry are at medium risk and dairy cows are at a very high risk.  As expected, corn gluten meal (CGM) contained the highest average values for ZEN (465 ppb), FUM (3,791 ppb) and OTA (17 ppb). Also, the highest incidences of Afla (62%), ZEN (71%), FUM (94%) and OTA (40%) were observed in CGM. It was not surprising to observe relatively high average concentrations of DON (1,241 ppb) and FUM (2,852 ppb) in DDGS, as it is known that during the production of bioethanol, many mycotoxins are concentrated in the remaining corn by-product.

Wheat and rice bran

DON is the most common mycotoxin found in wheat samples with an incidence of 67%. In wheat bran the DON incidence was even higher; 95% of the samples were above detection limits.The highest average DON concentration was detected in wheat bran samples (2,111 ppb) which is twice the amount found in wheat samples. Compared to wheat and wheat bran, rice bran samples contain higher average Afla (16 ppb) and ZEN (105 ppb) concentrations.
The highest maximum level of DON was observed in a single barley sample that originated from China (29,267 ppb). The concentrations of mycotoxins in soybean meal were relatively low compared to other cereals.

Finished feed and silage

As corn is one of the main components of finished feed, the most common mycotoxins, FUM and DON, were found at almost similar levels in both finished feed and corn samples. However, a lower percentage of finished feed samples tested positive for all mycotoxins except for OTA. Accordingly, the highest maximum OTA concentration was observed in a single finished feed sample (595 ppb). This level exceeds ten-times the EU guidelines for OTA in complete feedingstuffs for pigs (50 ppb) and would pose a high risk for all livestock animals. The average mycotoxin concentrations in corn silage samples were very similar to those observed for finished feed. The most common mycotoxin in corn silage samples was DON with a prevalence of 55% and an average concentration of 398 ppb, which poses a high risk for piglets.

Conclusions

The present survey highlights the variances in mycotoxin occurrence among different agricultural commodities. Distinct mycotoxin patterns can be observed in each commodity due to the individual plant’s susceptibility to fungal infection and subsequent mycotoxin contamination. The survey also showed that mycotoxins are a problem across all the different regions in the world, although the type of mycotoxin in the commodity can differ per region. Therefore, the analysis of different commodities from various regions is essential to obtain a clearer understanding of the worldwide occurrence of these fungal toxins. Implementing an effective mycotoxin risk management program is the best way to protect animals from the effects that mycotoxins have on health and performance.

Article featured in AllAboutFeed Volume 22 Issue 3
Click on link to read Part 1 of the Global state of mycotoxins