Uk farmers urged to plan ahead to tackle mycotoxins

Ever present in the farm environment, mycotoxins pose a challenge for all livestock systems, yet they often fall under the radar.

This can be at significant expense to a producer’s bottom line, causing reductions in health and performance that can significantly eat into profit margins says Andrew Linscott, ruminant manager at Alltech UK.

“Because mycotoxin producing moulds aren’t usually visible and the clinical symptoms of contamination are typically wide ranging and subtle, farmers often fail to pinpoint them as the cause of many health issues in livestock,” says Mr Linscott.

Signs of mycotoxin contamination can be subtle, but symptoms in cattle include:

• Inefficient feed utilisation
• Digestive disturbances
• Compromised health status such as increased somatic cell counts
• Compromised reproductive performance such as reduced conception rate and abortions

“This can be a major hidden cost to businesses and producers should take precautions to reduce the risk of in-feed mycotoxin contamination. This requires an all-encompassing approach, factoring in mycotoxin prevention, identification and if required, mitigation,” says Mr Linscott.

With ensiled feeds such as grass silage being a major culprit in UK livestock systems, he says prevention of mycotoxin contamination in forage really begins at harvest.

“Where possible, producers should try to avoid mycotoxin producing moulds being brought into the clamp in the first place. Attention should then turn to creating a stable storage environment, that doesn’t enable moulds and fungi to grow and proliferate.

“While adopting best practice during harvest and storage doesn’t guarantee mycotoxin free silage, it will help reduce any contamination, potentially bringing mycotoxin levels to within a safe limit,” adds Mr Linscott.

Top tips to reduce mycotoxin risk in silage

1.Ensile the crop at the correct stage of maturity.

“While a mature crop with lower digestibility value is often acceptable depending on what you are feeding it to, it’s worth remembering that older crops are more vulnerable to attack in the field by fungal pathogens,” says Dr Dave Davies from Silage Solutions UK. “This can then result in the production of field bourne mycotoxins, such as Fusaria, which will be transferred into the silage clamp.”

2. Adjust the cutting height.

“If the crop is more mature, consider a cutting height of at least 7.5cm to 10cm from the base of the stem,” advises Dr Davies. “The bottom of the stem poses the highest risk of diseased material and has the lowest digestibility and nutritive value. Therefore, while you will sacrifice some yield, crop quality will be improved and mycotoxin contamination risk reduced.”

3.  Wilt rapidly.

Dr Davies says the crop should be spread immediately in the field to achieve a rapid wilt. “This is especially important in heavy yields as leaving it in a swath reduces the evaporation of water and can trap moist air,” he explains.

“This creates a warm humid environment which encourages the growth of yeasts and moulds, that’ll then contaminate the ensiled crop, resulting in storage formed mycotoxins.”

4. Compact well, to achieve a target density of 750kg of fresh matter/m3 or 220-250 kg of dry matter/m3.

“This can be achieved by layering the forage in the pit in layers no thicker than 15cm and rolling each layer before the next load comes in.  By doing this, you’ll achieve the high density required, which’ll reduce the yeast numbers in the silage significantly. The result will be a much more aerobically stable silage, that shouldn’t heat up, therefore reducing the risks of mould growth and mycotoxin formation,” says Dr Davies

5. Sheet up well.

“It’s really important that the clamp it sheeted up well, following good consolidation,” says Dr Davies. He advises that producers use a side sheet, oxygen barrier film and top sheet, and then apply enough top weight, paying particular attention to the junction between the wall, the top sheet and the ramp.

“It’s vital to keep air out, as oxygen allows yeasts and moulds to survive and grow, reducing the nutritive value of the silage and increasing the mycotoxin risk.”

6. Good clamp management.

“While good harvest and storage management is key, it’s also important that livestock producers manage the clamp well when feeding-out,” says Dr Davies.

“The clamp face should be kept clean and tight; a shear grab is the best way to achieve this.  It’s also important that producers move across the clamp face as quickly as possible. Ideally, the clamp face should be moved across every three to four days, especially during warmer weather.

“The area in front of the clamp should also be kept clean and free of mud or manure, which could directly contaminate the feed or the clamp,” he adds.

7. Discard visibly mouldy feed. 

“While a lot of mould and fungi aren’t visible, some, such as penicillium moulds, are noticeable by sight. In this instance, it’s important that any obviously mouldy feed is discarded,” says Dr Davies.

He adds that it’s also advisable to clean out feeder wagons and troughs on a regular basis, which could become a source of mycotoxin contamination.

8. Carry out an Altech 37+ mycotoxin test.

Despite adopting best practice during harvest and when managing the clamp during feeding-out, there is still potential for mycotoxin contamination, adds Andrew Linscott.

He therefore advises that all producers should analyse TMR’s with a broad-spectrum mycotoxin test.

“Because mycotoxin contamination isn’t usually visible, the only real way to know whether there are mycotoxins present is to carry out a test. Not only is it useful to identify the type of any mycotoxins present, but it’s also important to determine the level of contamination, to enable producers to decide whether any further action is required to mitigate the risk to animal health and performance.”

Mr Linscott adds that in dairy herds, it’s important not to forget to test transition cow rations.

“With transition cows, close attention should be paid to the quality of the ration. A diet with relatively low levels of mycotoxins can prove costly, as transition cows already face challenges in relation to dry matter intake and immunity. The additional presence of mycotoxins can exacerbate these challenges, with knock-on effects at calving and during the subsequent lactation.”

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