Mycotoxin survey: Co-occurrence still an issue

The presence of mycotoxins in feed are associated with lower performance, health and reproductive issues and higher medical costs. Despite the fact that solutions are there to prevent mycotoxin formation or counteract the effects when animal digest the toxins, the prevalence of mycotoxins in all regions of the world remains a problem.

This is due to several factors, of which climate change is one of them. Felicia Wu from Michigan State University in the US states that climate change patterns (more rain for example) in the decades to come will affect mycotoxin levels in crops and consequently the costs for grain growers and feed mills. Extra costs can include for ­example the extra costs associated with testing at the level of grain elevators, handlers, and processors; as well as crop insurance costs for excessively high mycotoxin levels in certain countries. Costs will also rise because a substantial portion of food- and feedstuffs will be rejected for excessively high mycotoxin levels. For farmers, costs can be found in the economic losses associated with reduced animal production and compromised human health. The consumption of ochratoxin A (OTA) contaminated diets by broilers for example results in negative effects on poultry production, such as decreased body weight gain and kidney problems. In pigs, deoxynivalenol (DON) and fumonisins (FUM) have a negative effect on gut integrity: they decrease vaccine efficiency and render the animal more susceptible to pathogen infections.

Insight into prevalence around the world

Animal nutrition company Biomin is known for its annual comprehensive mycotoxin survey, which is already the largest and longest-running programme on mycotoxin occurrence. Thousands of samples are tested throughout the year for presence of the most important mycotoxins. These large datasets give a reliable and sound overview of the mycotoxin prevalence for all regions around the world, which help animal nutritionists, farmers and commodity traders in making better strategic decisions to improve livestock performance and save money. In 2016, the survey was bigger than ever. Last year, 99,066 analyses were performed in 16,511 samples. The samples were collected in 81 countries. This is far more than the 49,626 analyses, 8271 samples and 75 countries in 2015 (which was already far more than the 26,200 analyses, done in 2014). Those numbers are just for the six main mycotoxin groups. The survey also includes results of multiple mycotoxin analysis of 1,378 samples for more than 380 mycotoxins and metabolites, Spectrum 380®, using state-of-the-art liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) in a single analysis step.

Mycotoxins have a major effect on animal performance and health. In poultry, decreased body weight gain and kidney problems can be observed. Photo: Hans Prinsen

Greater focus on practical risk levels

This year the survey conveys risk levels in terms of the percentage of samples testing positive for at least one mycotoxin above the threshold level. The risk threshold levels for the most sensitive species are as follows: Aflatoxins (Afla); 2 ppb, Zearalenone (ZEN); 50 ppb, Deoxynivalenol (DON); 150 ppb, T-2; 50 ppb, Fumonisins (FUM); 500 ppb, Ochratoxin A (OTA); 10 ppb. For example, in Asia, the region where mycotoxin risk was the highest in 2016, the risk level is 80%.

This means that 8 in 10 samples had at least one mycotoxin above the threshold levels. This is the highest risk level seen for Asia since Biomin started its survey. The 2016 risk levels for all regions can be seen in Table 1. “For a producer in the field, an elevated risk level means that the odds of encountering mycotoxin contamination that could affect animal health or performance are indeed high. In light of the latest results, livestock producers should be vigilant in monitoring their feed and raw ingredients for mycotoxins,” states Dr Timothy Jenkins, Mycotoxin Risk Management Product Manager at Biomin.

Co-occurrence still an issue

The presence of multiple mycotoxins is referred to as co-occurrence. Mycotoxins seldom come alone and in practice,
a great number of samples are being contaminated with multiple mycotoxins as compound feed contains a mixture of several raw materials, each of them with their own mycotoxin contamination pattern. The co-occurrence of mycotoxins can affect both the level of mycotoxin production and the toxicity of the contaminated material. The challenge is to deal with these different mycotoxins in one sample, each having their own modes of actions. Co-occurrence in the Biomin Mycotoxin Survey samples is tested for at least three different mycotoxin types. The data shows that practically two-thirds (66%) of samples contained two or more mycotoxins. In 2015, 84% of all samples contained at least one mycotoxin and over 50% contained several. Multiple mycotoxin contamination of feed presents additional problems, as certain combinations of mycotoxins are known to have synergistic effects that intensify the negative consequences for animals. “The combination of DON and ZEN is a known synergistic pairing that disrupts gut integrity more than DON alone, reducing animal performance and opening the door to pathogens,” explained Dr Jenkins. “Similarly the effect of ZEN on reproductive systems can sometimes be worsened by the presence of DON.”

Regional trends

A year-on-year comparison of mycotoxin occurrence data reveals a number of key trends per region. As in previous years, DON and FUM are once again the main mycotoxins present.

North America

It was observed that Fumonisins rose with the 2016 harvest of North American corn. Although DON remained the most prevalent of the mycotoxins (58% of samples was contaminated with this mycotoxin) with levels assisted by rainfall around the silking (flowering) period, higher summer temperatures may have contributed to the rise of FUM. Year on year, the percentage of contaminated samples with FUM increased slightly from 39% in 2015 to 46% in 2016, but focusing specifically on the new corn harvest, the results were 66% in 2016 (with an average of positive samples of 3564 ppb) compared to 51% in 2015 (with an average of 1155 ppb). The overall risk level for 2016 is set at 66%. This is higher than 2015 (57%) but lower than the overall risk level observed in 2014 (68%).

Europe

Deoxynivalenol levels are elevated in cereals harvested in many parts of Europe. Conditions around flowering were wet in most European areas and conducive to Fusarium head blight. This disease produces ZEN as well as DON. 2016 saw a slight drop in samples contaminated with ZEN (from 64% in 2015 to 48% in 2016). This was also the case for DON (from 77% in 2015 to 70% last year). This is also why the risk level for whole Europe dropped from 65% to 58%. However, the risk levels have increased when comparing the last quarter (more relevant for the recent crop harvest) from 56% to 66%.

Asia

Asia faces a heightened risk of mycotoxins overall with a lift this year in the risk in Northern Asia and South East Asia (Table 2). The risk profile is very regional with prevalence of Afla being very high in South Asia (88% of samples) and DON being particularly high in East Asia (92% of samples).

Middle East

The risk level has reduced in the Middle East from 50% to 41% due to a somewhat lower prevalence of DON and FUM. However, the average levels of all the six main mycotoxins increased for the samples where the mycotoxins were detected.

Oceania

The annual results for Oceania have seen a decrease in risk levels from 28% to 16% for 2015 and 2016 respectively. Weather conditions in many areas of Australia and New Zealand may be conducive to higher levels of mycotoxins in pasture and crops in the current growing season.

Africa

Aflatoxins are a hidden and big problem in Africa. The percentage of samples contaminated with Afla increased from 21% in 2015 to 29% last year for Africa (excluding South Africa). However, contamination levels for the other mycotoxins dropped, compared to the year before. In South Africa, the Afla levels remain relatively low, compared to the rest of the continent (17%). The risk level for South Africa is however comparable to the rest of Africa. Looking at the quarterly data from 2016, we see that the risk levels for Africa (excluding South Africa) were the highest in Q3 and Q4 (Table 3).

South America

The risk level in South America jumped to 60% from 37% in 2015. This is likely to be largely related to high levels and bad timing of rainfall. For this region of the world, the samples from 2016 contained more often ZEN, DON and T-2. See Table 4.