The three genera of fungi (mould) Aspergillus, Fusarium and Penicillium are all known to infect crops, particularly crops under poor management conditions. If exposed to one or more of these types of fungi cattle can also become infected, resulting in a disease known as mycosis. However this is uncommon as cattle usually need to be immunosuppressed in order for the fungi to take hold. A more common problem associated with these fungi is mycotoxin accumulation. Mycotoxins are a type of chemical by-product (poison) used as a defence mechanism by fungi that can be incredibly dangerous to the health of animals. Humans occasionally come into contact with mycotoxins in the form of black mould in houses, whereas animals such as cattle can be exposed to them through infected crops used as feed.
These fungi are present as spores in the soil and on decaying plant matter and can easily infect a crop if the correct precautions are not taken. The Food and Agriculture Organization of the United Nations (FAO) has estimated that 25% of the world’s crops are contaminated with mycotoxins (1998), showing the prevalence of these toxic chemicals. Certain conditions must be right for fungal growth and thus mycotoxin production. If these conditions are not present, even if there is fungi, mycotoxins will not be produced. These conditions include aerobic environments with high moisture contents. A moisture content of <14% is considered low enough to prevent fungal growth and can easily be achieved by allowing crops to dry before harvesting and storing them in a dry location. Oxygen is also required for fungal growth and it is because of this that plastic wrapped hay bales and silage are not often affected by mycotoxin contamination, even though they have a high moisture content, as they are stored in an anaerobic environment. Oxygen is present at first but is quickly used up by the bacteria fermenting the feed, at which point anaerobic fermentation takes place.
Prevention of mycotoxin production by preventing fungal growth is the most reliable and safe way of protecting a crop. There are methods for detoxifying infected crops but they are expensive and unreliable. Maintaining proper silage making practices and storing dry feeds in <14% moisture conditions is usually sufficient to prevent growth but tests such as Mycocheck from Micron Bio-Systems can be performed to rule out the possibility of mycotoxin presence. As the symptoms of mycotoxin poisoning in dairy cows are very similar to SARA symptoms it is important to detect the cause of the problem and act accordingly to prevent further damage. Using the eCow eBolus you can monitor rumen pH levels in cows showing symptoms of mycotoxin poisoning or SARA and use the results to rule out acidosis.