Adopt a Preventative Approach to Mycotoxins in Maize Diets

All dairy farmers could benefit from protecting their herds against mycotoxins, according to the latest Mycocheck results which identified the toxins in over 90% of samples.

Nearly 800 animal feed and forage samples were tested in the UK & Ireland in 2025, with 93% of those positive for one or more mycotoxin, which is comparable to data from the previous year. Maize was also higher risk, with 99% of maize silages testing positive, versus 80% of grass silages.

Mycotoxins are produced by certain moulds which can grow on bought-in feeds and home-grown silages. These invisible toxins have wide-ranging effects including reduced feed efficiency, suboptimal yields, poor fertility and problems such as lameness and mastitis.

Profit drain

Rob Furmage, Scientific Services Manager for Volac believes the test results show that mycotoxins could be “silently eroding profit margins” on many farms.

“Usually, farmers don’t realise there are background issues caused by mycotoxins putting the brakes on performance,” he says. “If they’re present at low levels, they might be causing slightly reduced yields. You may not even know you could be achieving more.”

Anna Dinsdale, Ruminant Technical Manager GB & Ireland for Trident MicroNutri says pressure on milk price means farmers can ill-afford any drain on performance.

“There isn’t room this season for inefficiencies and that’s essentially what mycotoxins do to a herd. They can immuno-suppress or immuno-stimulate. If a cow’s immune system is switched on unnecessarily, that is very energy inefficient and diverts energy away from production,” she explains.

Not all moulds will produce mycotoxins, but a mould is more likely to produce a mycotoxin if it is stressed. Likewise, moulds don’t have to be visible for mycotoxins to be present.

Mycocheck results highlight the variability in mycotoxin risk both within the same year and between farms. For example, more samples had mycotoxins present in 2025, but the levels and type of toxin present made it lower risk on average than the previous. However, data analysis showed that various high risk geographical “hot spots” emerged through the year, which could have been linked to buying-in high risk imported maize-based feeds or environmental stress in a particular region, for example.

Rob says it underlines the unpredictability of mycotoxins and the fact they are always present in the background.

“Mycotoxins may be identified as low risk at any given time, but they can very quickly become an issue. For example, very wet or very cold or very hot weather might trigger them, but it’s hard to predict,” he explains.

Any stressor that increases the risk of mycotoxins can quickly tip the balance and lead to greater herd level issues such as poor fertility, diarrhoea or reduced feed intakes (see table) which can mistakenly be linked to any number of things such as genetics, management or poor silage.

Maize is particularly high risk for mycotoxins as moulds favour the crop due to the open ear structure and long growth period. That combined with warm, humid weather creates the perfect environment for moulds to flourish.

Anna believes the commonality of mycotoxins in feed and forage samples means it’s important to adopt an ongoing preventative strategy to protect cows from background low-level mycotoxins. This is even more vital when feeding maize silage or maize-based by-products such as maize distillers.

Preventative approach

She advises including the triple-action mycotoxin remediator and endotoxin binder, Ultrasorb in all diets at feed-out. Unlike a straight clay binder which simply binds a small number of mycotoxins, Ultrasorb binds, transforms and degrades a wider range using a combination of specifically selected clay binders, yeast fractions and biological active agents. This makes it effective against mycotoxins that are difficult to bind such as DON and ZON. It is available through Trident MicroNutri in the UK and can be incorporated into the diet in multiple ways including in blends, minerals or as part of a farm pack.

Anna says it can be used at a preventative, standard rate of 10g per cow per day or 20g per cow per day should a high-risk mycotoxin/endotoxin problem be identified.

“Using Ultrasorb costs pennies per cow per day. If preventative measures are not taken and milk production falls due to mycotoxin intake from the ration, it takes time to get that milk back during which time you’re losing income,” she explains. “Feeding it preventatively takes the worry away and it also opens up a whole feed library as you don’t have the same level of concern over higher mycotoxin risk materials.”

Having the product already on-farm also means it’s possible to react quickly should mycotoxin challenge rise due to issues with a feed or forage. “Why risk not protecting cows by using a binder when you know they’re there and can cause damage to health and performance?” Anna asks. “It’s about taking a proactive approach rather than waiting for a problem.”

That said, if health and production issues are being seen, Anna urges farmers to consider mycotoxins as the potential cause sooner and test the diet for mycotoxins – without testing, it’s impossible to know if they are present.