A poultry farmer’s guide to using mycotoxin binders in feed

Fungi produce toxic substances, known as mycotoxins, as a form of defence against the environment.

The development of mycotoxins is subject to specific environmental factors, such as warm temperatures, high humidity and the presence of nitrogen and oxygen. 

The three predominant types of fungi – aspergillus, fusarium and penicillium – are often found in cereal crops that have suffered wet weather or insect damage before harvest, or they develop over time during storage. 

See also: Everything you need to know about poultry feed additives

When ingested, mycotoxins can have serious implications for all livestock, including poultry. Health risks include growth retardation, infertility, immunotoxicity, liver failure, intestinal destruction and even death.

The latest research shows that even subclinical exposure to mycotoxins will affect productivity, says microbiologist Hsueh lui Ho of Micron Bio Systems.

More than 300 mycotoxins have been identified, but the most common found in feed are:

• Aflatoxins
• Trichothecenes
• Zearalenone
• Fumonisins
• Ochratoxins
• Patulin
• Ergots.

How do feed binders help?

Feed binders are usually composed of a mix of clay minerals (bentonites, sepolites, kieselgurs) or algae materials.

As the name suggests they bind to the mycotoxin in the gut of the animal, a bit like a magnet, preventing its absorption so that it is simply passed through and excreted.

Most binders work well at low pH levels, but binding capability drops as pH rises. The pH of a chicken’s intestinal tract varies from about 2.5 in the proventriculus or gizzard to pH5-6 in the duodenum.

To address this, remediators – a combination of binders and enzymes/micro-organisms – can be used to detoxify or break down the mycotoxin.

What are the potential benefits?

Depending on the type of mycotoxin present, the benefits of using a binder include:

• Better feed conversion ratio
• Improved bodyweight 
• Higher egg production
• Increased fertility
• Better health and immunity
• Improved gut health
• Less risk of mycotoxins entering the human food chain.

How can they be introduced to a diet?

Binders are added to the complete feed. Some farmers will put them in all feed as a preventative measure; others will only use one when they start seeing a problem.

Vet Richard Turner from St David’s Poultry Team says broiler integrators tend not to use mycotoxin binders in their rations due to the added cost.

But he questions that thinking, because there is firm evidence of health and litter problems caused by mycotoxins in feed.

“In southern Europe it’s routine to use binders, and I think they should be used more routinely here,” he adds.

“I see evidence of gizzard erosion, which is a classic sign of mycotoxins – from that you get rapid feed passage, leading to poor litter quality.” 

Binders are approved for use by the European Food Safety Authority (Efsa) and the UK’s Food Standards Agency because there are no known side effects.

There are some concerns that binders will also bind minerals and vitamins, which means there is less available for the animal. However, diets are usually reformulated to ensure there are sufficient quantities of both minerals and vitamins present.

Under Efsa rules a binder needs to show greater than 90% binding of aflatoxins at a level of pH5. All binders should be composed of materials that are approved for safety on the feed material register.

What will it cost?

Most binders cost £2-£3/t of feed at an inclusion rate of 1kg for each tonne of feed. A basic product purely binds the mycotoxin. But a more sophisticated remediator binder will transform and detoxify the mycotoxins, depending on the mode of action.

Cost is often used as a reason not to include binders in feed, says Mr Turner. “But why wouldn’t you pay £3/t when you get the results? If I were formulating a ration, it would certainly have a binder in it.”