Advice on managing mycotoxin risks for poultry

Despite the rollout of new stricter limits on the permitted levels of mycotoxins in cereals for human consumption, no changes have been made to recommendations for parameters in animal feed.

Regulators are satisfied with the existing legal limits for poultry. But what has changed since the limits were set more than two decades ago is the prevalence of mycotoxins.

Changes to weather patterns and agronomic practices mean they are much more common, and this presents a particular threat to monogastrics.

See also: Why a poultry and arable unit uses ‘circular feeding’

Unlike ruminants, poultry rely solely on one feed source for their daily nutritional needs, so there is no “dilution” effect from another forage if mycotoxins are present.

This is why the thresholds are lower than for cattle and sheep.

Teagasc poultry adviser Rebecca Tierney points out that if meal is contaminated it will inevitably put poultry at risk.

They have a greater vulnerability to mycotoxins because of high feed intakes.

“The bird’s digestive system works hard, it is working all the time, and this puts it under stress,” she says.

Snatched harvests and poor storage lead to grain contaminated with mycotoxins © Tim Scrivener

Under UK animal feed legislation, legal limits exist solely for the mycotoxin Aflatoxin B1 in feed raw materials and finished compound feeds.

Although there are also guidance values for other key mycotoxins, complete elimination of mycotoxin contamination is therefore impossible and, despite regulations, poultry can still suffer adverse health effects.

Rebecca gives her advice on what farmers should look out for and how they can mitigate the risks.

Apply caution with every feed delivery

It is sensible to treat every new delivery of feed with caution because of the sheer prevalence of mycotoxins.

Wetter growing and harvesting conditions in combination with warmer temperatures at storage are reasons why contamination is now more likely.

“We are seeing more ‘snatch-and-grab’ harvests – farmers combining in between periods of rain – and that means wetter grain,’’ says Rebecca.

High energy costs and the additional financial pressure to a business from drying grain can also be a factor.

This means some grain is going into storage with higher than desirable moisture levels, when mycotoxin growth could already be developing.

Warm, damp grain provides ideal conditions for moulds to grow and if on-farm storage facilities are not up to scratch, that contamination will intensify.

Rebecca suggests that everyone involved in the poultry feed chain, from the grower and harvester to the mill and broiler or egg producer, can play a role in minimising risks from mycotoxins.

“The farmer growing the grain could rotate crops to avoid the build-up of fungi, and grow varieties that are more resistant to mycotoxins,” she says.

“The weather at harvesting is obviously a huge factor and where it is impossible to take it off the fields in dry conditions, with a low moisture content, it is more important than ever that grain must be dried and stored in dry, cool conditions.’’

Application of fungicides to growing crops can also help reduce risk, as can minimising soil contamination during the storage period.

Understand health risks

Different mycotoxins have different impacts on poultry.

These can vary according to bird species, life stage, how long (and at what level) the bird is exposed to a specific type, and its health status at the time of exposure.

Rebecca says the consequences to poultry from ingesting mycotoxins was brought into sharp focus in Ireland in 2024.

Contaminated feed, thought to have originated from imported grain, affected a large number of flocks.

“In broilers we saw it manifest as slow growth and mortalities, and in commercial layers the mortality rates were high and there was reduced output of eggs and poor shell quality.”

At least two flocks had to be depleted prematurely, she adds.

“That had major consequences for financial viability because producers had already incurred the high, up-front costs of paying for the birds and the period when the flock is consuming feed, but not in lay.’’

Spot the red flags of mycotoxin contamination

When contamination levels are high, there will be physical evidence of it: the feed will be darker in colour and dusty.

It probably will not flow well from the storage bin to the in-shed feeders.

“You might find that you need to tap the bin to dislodge the feed,” adds Rebecca.

But the behaviour of the birds can often be the first sign of a problem because contaminated feed will have a smell and taste that makes it unappetising.

This will put the birds off eating it, inevitably resulting in reduced performance.

© Tim Scrivener

And if they do consume it, some mycotoxins can cause poor egg quality, fewer eggs, and diarrhoea, which will make the litter wet and cause consequential health issues such as pododermatitis.

The bird’s immune system can be compromised too, so if it is challenged by bacteria, it can hit them a lot harder and cause disease.

“If they are not eating their daily nutritional requirement they haven’t got the energy to fight off infection, and that increases their susceptibility to any disease challenges that might result from bacteria that are present,” says Rebecca.

She also points out that mycotoxins will also reduce bird fertility.

Know your data

While mould might not be visible, or changes to the feed colour and smell obvious, data can quickly highlight an issue, for example, changes to daily weight gains or egg numbers.

“The alarm bells should ring straight away when the data fluctuate from what is normal for your system,” says Rebecca.

Having data means that if feed is the cause of a problem, it can be removed swiftly before the situation escalates.

Mycotoxins can cause poor egg quality and a drop in quantity © Tim Scrivener

Using mycotoxin binders and blockers

Binders and blockers can shield poultry from the negative effects of mycotoxins. These work in slightly different ways, but achieve the same outcome of preventing harm to the bird.

A blocker stops mycotoxins from being absorbed, whereas a binder sticks the mycotoxins together to enable the bird to excrete them in their faeces. They can be added at different rates.

If a feed mill is aware that it has levels of mycotoxins slightly higher than the guidance for poultry, they can add a binder or blocker to the feed to reduce the risk.

“There is an obvious cost involved by adding these, but it is less than the cost of the detrimental impact on poultry,” says Rebecca.

She points out that mills producing poultry feed generally operate to very high standards because they are well aware of the issues.

There is an added layer of protection in Ireland because all feed destined for poultry is heat treated, principally to kill salmonella-causing bacteria.

UK-milled poultry feed for domestic use is not heat treated because producers vaccinate for salmonella.