A world mycotoxin survey has shown how widespread mycotoxins are in both grains and forages. Feed samples can now be tested for up to 700 different mycotoxins. Models for predicting risk are being developed which take account of weather (temperature, rainfall, humidity). If high risk is predicted, this could lead to earlier testing or more intensive testing, and could guide what to test for. Some predictions may indicate it is better to harvest earlier, and get less tonnage, but a cleaner crop.
Mycotoxins in forage can come from some of the same fungi that grow on grains but also from endophytes growing within the plant. The fungus that causes facial eczema, Pithomyces chartarum, grows in dying grass shoots and is now becoming more reported in parts of South America, southern USA and southern Europe.
Although the rust fungus does not itself produce mycotoxins, orange boots when walking through pasture indicate increased risk of mycotoxin-producing fungi. The rust fungus breaks the leaf surface which allows zearalenone- and trichothecene-producing Fusarium to get established.
Mycotoxins in silage can come from both fungi that grew on the crop prior to harvest and those that can grow in the silage. The latter tend to be fungi suited to low oxygen conditions such as Penicillium roquefortii and Aspergillus fumigates, both of which produce harmful mycotoxins. Aspergillus fumigates can also grow inside an animal (gut and lungs), so it is best not to sniff silage which could contain this fungus.
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