High mycotoxin levels need proactive management

Published 19 December 12

mycotoxins

This year is shaping up to be one of the worst for mycotoxin contamination in grain for a long time. In fact, it's estimated that 50 per cent of grain has Fusarium mycotoxins on it following extreme rainfall and cold temperatures weather this summer, with the potential to have a big impact on livestock health and performance. DairyCo's R&D Manager Debbie McConnell talked to  Alltech's Graeme Smith about the issue.

Mycotoxins are produced by moulds that have been stressed by environmental and management factors, such as extremes of temperature, drought, flooding and harvesting technique. They're toxic to animals in low concentrations and exhibit strong physico-chemical resistance.

There are three main mould groups of concern: Fusarium, Aspergillus and PenicilliumFusarium  moulds are of field origin, ie they proliferate on the crop while still in the field and are found on grain - meaning they can also be found on wholecrop silages. Aspergillus and Penicillium  develop during storage of the crop and can be found on silages.  While Aspergillusis less of an issue in the northern parts of Europe, levels of its associated mycotoxin, Aflatoxin, are regulated under EU law.

In terms of negative effects on farm, the Fusarium and Penicillium mycotoxins are by far the most problematic in the UK. As mycotoxins are very stable compounds that 'survive' on the crop or grain long after the initial mould has disappeared, the absence of mould does not necessarily mean the crop is 'clean' (the reverse situation also applies) and, although routine testing is carried out for mycotoxins, producers utilising home-grown grain and conserved forage to feed animals on farm may be at increased risk of introducing a mycotoxin challenge to their animals.

Mycotoxins compromise animal health and performance. Signs of mycotoxin challenge include reduced milk yield, poor growth, swollen joints, 'dull' appearance and lethargy. It's important to note that many of the symptoms associated with mycotoxicosis are non-specific, often meaning that a mycotoxin issue is 'last in the queue' when diagnosing.

Graeme Smith says the main effect of many mycotoxins is impairment of the immune system. "Animals that are immune-compromised will be a greater risk of pathology from other infectious and metabolic diseases simply as a result of their weakened state," she explains. "Other effects include gastrointestinal disturbances, feed intake depression and reproductive abnormalities. Cystic ovaries, irregular cycles and embryonic abnormalities are all also possible."

He says probably one of the most important but underestimated effects is the antibiotic action of Penicillium mycotoxins. "Patulin, PR toxin and Roquefortine C are all produced by Penicillium moulds and have the same action in the rumen as Penicillin does in the human body - antibiotic.

"It's true that ruminants are less susceptible to many mycotoxins compared with non-ruminants because of the ability of the rumen microbes to degrade them to less harmful compounds. However, if this ability becomes impaired by an antibiotic action, then the animal becomes increasingly susceptible to those mycotoxins."

As Penicillium is a storage mould, 'stressors' during harvesting and ensiling lead to proliferation of associated mycotoxins. Contamination avoidance is virtually impossible but following good silage management practices can go a long way to minimising the risk to livestock. Again, the variability in, and timing of, this year's weather has done little to help the situation.

Graeme says: "One of the key points is the recognition and understanding of the mycotoxin problem. Part of this is recognition of the fact that the majority of exposure is to chronic, low concentrations of multiple mycotoxins and, as such, any interventions, including use of a mycotoxin binder, must be able to deal with a wide suite of mycotoxins at any one time. As mentioned previously, mycotoxins are often the last in the diagnostic queue and traditional analyses used for their detection often lacked sufficient sensitivity."


In conclusion, mycotoxin contamination is unavoidable, however, negative effects can be minimised through knowledge and understanding of the threat they pose. If you suspect that mycotoxins may be a problem on your farm, it's advisable to test your forages and any home-grown cereals. New technology has meant testing for mycotoxins has become much cheaper (<£10 per sample).
 

More information on testing can be found on the HGCA website

If you have identified high levels of mycotoxins on your farm, introducing rumen buffers, mycotoxins absorbers or particle binders may help alleviate this problem.   Alltech's Graeme Smith offers this advice when selecting mycotoxins binders:

  • Select scientifically proven products. 
  • Avoid clay-based products: clay is ineffectual against Penicillium mycotoxins and binds vitamins and minerals, preventing their use by the cow. 
  • Select broad spectrum binders to deal with the broadest range simultaneously.
  • Choose fast acting products - in the blood stream within 20 minutes.
  • Be aware of the European Animal Feed Regulations (legislation 767 2009)

Beware of products purporting to bio-transform mycotoxins.  This can be more harmful than the original mycotoxin.