Mycotoxin Outlook

Mycotoxin Outlook

As farmers begin to dip their toes into cereal crops around the country, yields are the focus for every arable farmer. AHDB has predicted a UK wheat crop that could be as low as 10Mt, which would be the lowest seen this millennium. Winter barley also looks to have struggled through the spring drought, although the total barley crop is likely to recover due to the large amounts of spring barley planted.

As there is plenty of wheat around the world it is still likely to play a significant part in winter rations this year. However, it is also predicted that imports of maize will be higher and likely to feature in many winter rations. It is important that we are aware of the mycotoxin threat posed by crops grown in different climates as maize for example is especially susceptible to mycotoxin contamination – we see a very high proportion of maize samples having at least one mycotoxin through our Mycocheck service.

Considerations for Imported Feedstuff

1. The Different Climate

Cereals crops are imported from around
the world with the majority coming from
a warmer climate than the UK. Fusarium moulds are the most common in the UK and Ireland, with the temperate/wetter climate and this leads to the production of the mycotoxins such as Deoxynivalenol (DON) and Zearalenone (ZON) amongst others.

Aspergillus moulds that produce Aflatoxins are much more common in warmer & drier climates with higher temperatures. Due to the higher levels of imported feeds, we will see this winter, farmers and feed companies should be on the lookout for symptoms associated with Aflatoxins, as well as the more common DON and ZON mycotoxins from Fusarium moulds.

2. Transportation and Storage

Most moulds that produce mycotoxins are produced in the field before harvesting, however, transportation and storage can also pose a risk, especially when travelling long distances in hot confined containers. These warmer conditions tend to favour Aspergillus moulds and the production of Aflatoxin.

Symptoms of Aflatoxin Contamination

The most common symptoms to look out for with high level of Aflatoxin contamination are:

• Depressed milk yield by as much as 25%
• Significantly reduced reproductive efficiency • Reduced rumen efficiency
• Gastrointestinal upset

How does mould produce mycotoxins?

Moulds produce metabolites at different stages during their lifecycle:

1. Primary metabolites are produced continuously during the exponential phase of growth and are involved in primary metabolic processes such as respiration.

2. Secondary metabolites are compounds produced and are not required for primary metabolic processes, e.g. during reproduction.

Mycotoxins are poisons generated from the secondary metabolic process which occurs naturally in a wide variety of moulds.

Mycotoxins can be present even if there isn’t visible mould on the feedstuff

It has been estimated that over 80% of all mycotoxins are formed pre-harvest with mould growth being present in the stalk or grain of the plant or in the soil. When the crop is then harvested the mould is dispersed through the feed. This allows the mycotoxins to be present in the feed without being visible, so the threat often goes unnoticed.

What does it mean if there is visible mould on the clamp face/feed?

The colour of the mould is an important factor
in understanding its metabolic stage (primary or secondary) and also the type of mycotoxin risk it presents.

• White mould: Commonly seen on feedstuffs especially on open clamp faces. White mould
is still in the primary metabolic phase so it isn’t producing mycotoxins but it is still damaging the feedstuff (Figure 3). When the white mould starts to reproduce, the spores are pigmented and the colour of these spores help to identify the type of mycotoxin present.

• Pink/Red mould: Indication that the feedstuff is contaminated with a fusarium mycotoxin (DON, ZON, T2) (Figure 4). In UK & Irish climates this is the most prevalent mycotoxin.

• Green mould: Indication that aspergillus mycotoxins (aflatoxin) are present.

• Blue mould: Indication of a penicillium mycotoxins.

Top Tips

1. If using homegrown cereals, walking the field pre-harvest and checking for visible mould will provide an indication of whether the feed is going to present a risk to animal health and performance.
2. If you spot white mould growth on feedstuffs, then continue to monitor any changes in the colour/size of the mould, as environmental triggers can cause the mould to enter the reproductive stage, producing mycotoxins