Mycotoxins: An invisible dark side of climate change
Climate change is expected to have a severe impact on the development of mycotoxins in crops, with negative consequences for livestock health and performance. Farmers need new tools to overcome the challenges in animal feed.
BY KRISTINA SØRENSEN, PH.D, PRODUCT MANAGER, VILOMIX C
limate change poses a huge threat to agriculture around the world. Rising temperatures, extreme weather and abnormal variations in rainfall are bad news for crops and livestock. Under these condi-
tions, toxigenic fungi have excellent opportunities for growth. Along with them come mycotoxins, which rank among the most dangerous contaminants in animal feed. If left untreated, mycotoxins can have serious consequences for reproduction and other aspects of livestock performance. Mycotoxins are secondary metabolites of pathogenic plant fungi. Hard to detect and often undiscovered, they frequently develop in agricultural commodities and pose a hazard to hu- man and animal health. A range of environmental factors cre- ate the optimal conditions for growth, before or after harvest and during storage.
Factors beyond control Our inability to control the most important environmental factor – the weather – is the reason why mycotoxins accumulate most frequently pre-harvest. Interactions between fungi, the host plant and the weather determine the extent of the mycotoxin contamination. The local climate also
Mycotoxins and their origins
More than 700 secondary metabolites of fungi have been described and classified. The best known are: aflatoxins (AFLA), produced by Aspergillus fungi; ochratoxins (OTA), produced by species of Aspergillus and Penicillium; and deoxynivalenol (DON), T-2 toxin, fumonisins (FUM) and zearalenone (ZEN), produced by various species of Fusarium. Depending on the environmental conditions, single fungal isolates can produce a variety of mycotoxins before or after harvest and during storage.
32 ▶ MYCOTOXINS | NOVEMBER 2021
plays an important role by affecting plant growth and phenology, such as flowering time. Indirect influences on mycotoxin development include the presence or absence of insects and pests and plant stress due to droughts. As climate change progresses, mycotoxins are expected to become increasingly prevalent in agricultural commodities. Increasingly variable weather may create favourable conditions for mycotoxin build-up during critical windows of plant growth. For example, droughts can increase the risk of aflatoxins (AFLA) and rains after flowering can lead to higher production of deoxynivalenol (DON). All over the world, rising temperatures are likely to alter the risk map regarding the prevalence of specific fungi and the mycotoxins they produce.
The complexity of prediction The true nature of climate change is full of unknowns. However, even if we had a clear idea about what lies ahead, predicting changes in mycotoxin occurrence would be far from straightforward. This is because the interactions between pathogens, host plants and weather are complex. A variety of mycotoxin-producing fungi infect different plants. Among these fungal species, a little-known competitive interaction takes place. Today, researchers around the world are working hard to understand this interaction. Their ambition is to establish models for predicting changes in mycotoxin occurrence due to a warmer temperature, shorter crop cultivation period, earlier flowering and a rising level of atmospheric CO2
, for example. Such
models could play a key role in preparing feed solutions that protect animal health as well as performance. Data gathered over the past decade gives an indication of potential trends in mycotoxin occurrence within Europe (Figure 1). In wheat crops, data from 2013 to 2021 shows a trend towards increasing fumonisin levels in Southern, Northern and Central Europe. A similar trend has been identified for aflatoxins in Central and Northern Europe. On the other hand, aflatoxin prevalence in Southern Europe has declined during this time-frame.
Serious impact on animal health Mycotoxin contamination of feed is a cause of significant health problems in poultry, pigs and ruminants. Even when feed only contains low concentrations, mycotoxins build up
PHOTO: VILOMIX
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