Mycotoxins from contaminated feedstuffs can directly or indirectly cause a range of economically significant problems in cattle - but much can be done to minimise, though not eliminate, these risks through good practice

The toxins, generated by microscopic fungi, affect the full range of farm livestock but the effects can vary. In dairy cattle the first signs are usually a lowered dry matter intake and a drop in milk production. In addition they are likely to be linked to problems such as lameness and mastitis as well as issues related to liver function

Some of this may be the result of lowered immunity rather than caused directly by mycotoxins. Acidosis in the rumen can also reduce the animal’s natural protection mechanisms against mycotoxins.

It is generally accepted that there is no way of totally excluding mycotoxins from the feed of dairy cows. The next best approach is to minimize their presence and effect.

Farmers can ensure that crops grown to feed their cows are subject to good husbandry practice. It has been found that under field conditions stress and reduced vigour often make plants susceptible to infestation and colonization by toxigenic fungi. Varieties that are more resistant to fungi should also be used where possible. Trials using the application of non mycotoxin producing strains of fungi to the crop to out compete the toxic strains has shown great promise

Harvest of the crop and the possible damage to the grain can allow more substrate to become available for mould growth, hence increasing the amount of potential mycotoxins produced. Insect damage in store will also have the same effect.

Most important is the control of moisture and temperature in the stored material with research indicating a moisture content for stored grain of less than 15 per cent within 48 hours if possible in order to limit mould growth in the store. Alternatively chemical treatments with fungicides and organic acids are effective in limiting the potential for mould growth. The most effective organic acid treatment is propionic acid.

Robert Skelton

Dugdale Nutrition