Moulds produce mycotoxins as a natural immune system. The presence of these mycotoxins may vary greatly since the development of moulds in the field (e.g. Fusarium spp.) or during storage (e.g. Penicillium, Aspergillus) depends on several factors. This makes it very difficult to estimate the exact extent of the damage caused. Therefore it is recommended to regularly sample the feed, both when fungal and/or mycotoxin contamination is expected and preventively. 

Predisposing factors

In general, environmental conditions – heat, water, and insect damage – cause plant stress and predispose plants in the field to mycotoxin contamination. However, weather conditions are difficult to control and a thorough monitoring of the crop should be applied to prevent these moulds.

Because feedstuffs can be contaminated pre- or post-harvest, control of additional mould growth and mycotoxin formation is dependent on storage management. After harvest, temperature, moisture content, and insect activity remain the major factors influencing mycotoxin contamination of feed grains and foods. Storage conditions should be very well fine-tuned to avoid mould growth.

Adverse effects of mycotoxins

Symptoms of acute mycotoxicosis: nausea, vomiting, abdominal pain and diarrhoea.

Symptoms of chronic mycotoxicosis: reduced feed intake, reduced growth and development, suppression of the immune system, some types of cancer, foetal malformation, birth defects, disturbed embryonic development during pregnancy and toxic effects on fertility.

 Intoxication with mycotoxins occurs by eating contaminated feed. Since mycotoxins are usually not degraded during digestion or temperature treatments, these compounds can accumulate to high doses in feed products, in this way forming a serious risk for and animals. Many symptoms are associated with mycotoxin intoxication (mycotoxicosis), most of which are well described in animals. Mycotoxicosis can occur at two levels: acute illness due to intake of high levels of mycotoxins and chronic illness due to regular low level intake of mycotoxins. 

Because of the serious health risks, it is very important to monitor mycotoxin levels during the feed production chain. Monitoring involves a correct sampling method as well as an accurate detection technique.

Sampling: the start of a reliable assay
Moulds (and therefore also mycotoxins) never have a homogeneous distribution pattern. Often point source contamination occurs in the field or during storage. Therefore some parts of the feed or the raw material will be free of mycotoxins whereas other parts will have very high values. Traditional methods of sampling and sample preparation of agricultural crops are usually not adequate for mycotoxin analyses because mycotoxin contamination is usually heterogeneous, which creates problems in obtaining a representative sample for analysis.Therefore correct sampling is extremely important. The highly non-uniform distribution of mycotoxin contamination, requires a sampling plan that takes this heterogeneity into account. Figure 1 illustrates this. The number of incremental samples to be taken depends on the weight of the lot and kind of feed material that is sampled.

Figure 1: Correct sampling of materials potentially contaminated with mycotoxins

Rapid & accurate mycotoxin assay
Methods using liquid of gas chromatography and electrophoresis are tedious, laborious, time-consuming, require sophisticated equipment and/or trained personnel, and cannot be used in situ. Therefore simple and reliable methods of analysis are needed within the feed industry for the purpose of internal control. Therefore the Nuscience laboratory has implemented Quantitox. This device uses a Rapid One Step Assay (Figure 2) and is not...