Holistic approach to multiple mycotoxin challenge

Adams is global director of Alltech’s expanding mycotoxin management team and bases his conclusion of the company’s latest analysis of more than 7,000 livestock feed samples tested worldwide since 2012. “The recent results from this analysis confirm that the spectrum of mycotoxins naturally contaminating common feed commodities is much broader than people think – whatever continent you are farming on,” said Adams. “On average seven different mycotoxins contaminate each feed sample with up to 20 different mycotoxins being detected in some common livestock feeds. Only 34 of the 5,949 feed samples tested over the last three years contained no detectable mycotoxins.”

Climate change and new feed storage

The data reveal that the most prevalent feed mycotoxins worldwide are Fumonisins, Type B trichothecenes and fusaric acid, but tricothecenes A, ergot alkaloids and significant others – such as Aspergillus and Penicillium toxins found in stored feed – account for 30% of the mycotoxins found. Aflatoxins tend to be a threat in warmer areas of the world, or in regions feeding significant levels of grain that have been grown in warmer climates.

When there’s too much air in the forage, this will potentially increase mould growth and hence lead to mycotoxins in the silage.

“Climate change and feed storage practices do seem to be starting to influence the range of moulds occurring in farm feed stocks,” said Adams.“ And with traditional tilling and crop rotation practices diminishing too in many developed countries, mould contamination is persisting year-on-year, making the multiple mycotoxin threat very real. We are definitely seeing more and more cases every year in many of the 128 countries in which we are present.

“One of the reasons is the rise in unusual seasonal weather in some countries. For example, 2014 was the warmest year on record in in the UK. Mycotoxins are products of mould metabolism, so anywhere that moulds can grow is a potential source of a problem. However, it is the simultaneous presence of various mycotoxins that increases the potential toxicity to livestock.”

Cumulative effect

According to Adams, it is important to give livestock producers a more 
accurate picture of total mycotoxin contamination in their feeds. And, importantly, the overall risk that any toxin group is likely to have on the animals being fed. “Livestock producers are often concerned about which mycotoxin is the main contaminant, but even mycotoxins persisting at very low levels add to the total contamination of the diet. This is because mycotoxins have a cumulative effect whereby the presence of one can contaminate the effect of another. That’s why it’s so important to undertake a risk assessment process so farmers can better understand the most effective steps to take to mitigate the threat to livestock performance,” said Adams.

Proper cleaning of feed silos is essential. Hot weather conditions can increase mould growth in the silos, leading to contamination of the compound feed.

MIKO audit on farm

“On the farm our MIKO audit starts with examining the grains and other feeds stored on the farm, looking for evidence of mould growth and exploring issues such as where the feeds are stored (e.g. are they exposed to rain and humidity), their delivery pattern and we also use temperature probes and a thermal imaging camera to look for hotspots that indicate potential mould activity,” he explains.

The single most important management tool

“This builds a picture of the potential threat and allows us to make practical recommendations such as storing feeds a metre from a wall to prevent moisture accumulation. When feed is stored adjacent to an external barrier it is more exposed to the heating and cooling of the wall and this presents a mycotoxin risk. Making sure all the feed is removed and the floor/walls are cleaned before new loads come in is essential to prevent cross batch contamination and spoilage. In fact the control of moisture during storage is the single most important management tool to keep mycotoxins under control,” he continued.

Pit face management and daily removal rate

On ruminant livestock units the on farm assessment then looks at forage storage, examining similar issues with respect to conserved grass and maize in the clamp. “We also look at pit face management and daily removal rate – whether the forage is shear grabbed or simply pulled from the face with a loader – silo structure, additive usage and packing density,” Adams explained.

“We tend to tell beef and dairy farmers that if you can push your fingers into the clamp face easily, there’s too much air in the forage and this will potentially increase mould growth. Silage clamps should be really well compacted to drive out this air and good quality covers with plenty of weight in them are essential in this respect,” he said.

Nick Adams: “Livestock producers are often concerned about which mycotoxin is the main contaminant, but even mycotoxins persisting at very low levels add to the total contamination of the diet.”

Observing the livestock

After the feed risk assessment, the stock on the farm is studied to build up a picture of their overall health and fertility. “On the majority of units it’s difficult to see any definitive evidence of animals suffering from mycotoxin problems. The signs may be many and varied – such as sunken eyes, poor condition, low rumen fill and loose dung in cattle – but after you have gained a feel for the potential mycotoxin challenge from the feed assessment, you do get an inkling for how problems may be manifesting in the livestock, even though they may be quite subtle,” continued Adams.

Diagnostic assessment

Following their MIKO audit, the farmers receive a written summary report. The company can also build a better risk assessment picture through analysis of the levels of different mycotoxins actually present in the farm feeds using its 37+ diagnostic programme.

“Once we have processed all the data from the farm visit we are then able to offer a diagnostic assessment based on a percentage score. This ranges from 80%+, which suggests an excellent mycotoxin management plan is already in place; to 40-80%, which suggests some improvements could be made, through to 40% and below where there is a high risk of mycotoxin contamination.

We also offer advice on how to improve the management of stored feeds. It is only then that we start talking about appropriate use of a proven broad-spectrum mycotoxin adsorbent, where necessary – and at what feeding rate – to negate any damaging effect on the health and performance of the livestock operation,” Adams explains.