Written by Manuel Contreras, Poultry specialist
Mycotoxin contamination in poultry feed is a persistent challenge in commercial production worldwide. Among the various mycotoxin groups, Fusarium toxins have gained increasing attention over the past decades not only due to their widespread presence in commonly used grains, but also because of their capacity to interact with and amplify the effects of other toxins. Understanding which Fusarium toxins are truly relevant in poultry, how to identify them, and how to select and evaluate effective control strategies is essential for any poultry health professional. This article provides a practical overview of the main Fusarium toxins affecting commercial poultry, the tools available for their detection, and the criteria for choosing and validating anti-mycotoxin additives.
The Fusarium mycotoxins group includes Zearalenone (ZEA) and Fumonisin (FUM). For decades, both toxins were considered irrelevant to a certain extent, in commercial poultry but are now constantly evaluated in feed analyses and considered important mycotoxins affecting performance. In the case of ZEA, despite being frequently present in grains and used as a marker for other mycotoxins, scientific and field reports indicate that it is not very toxic in either broiler chickens or hens. The situation with FUM is different because most of the corn produced globally shows its presence. In corn harvested in the United States, Argentina, and Brazil, it is common to detect levels of 1,500 to 4,000 ppb of FUM. As a result, many clinicians are diagnosing mycotoxicosis caused by FUM in cases where the etiologic agent is completely different. Inclusion Body Hepatitis (IBH), for example, is frequently misdiagnosed as mycotoxicosis.
Inside the Fusarium toxins, there is another classification called Trichothecenes, characterized by a similar chemical structure, which represents another important group affecting performance and causing specific gross lesions. T-2 toxin, DAS (diacetoxyscirpenol), and Vomitoxin/DON are the most relevant. The oral lesions caused by T-2 toxin and DAS are easily identified as a sign of mycotoxicosis in poultry farms. In the case of DON, identifying typical gross lesions is more difficult, though several scientific papers report microscopic damage to intestinal integrity. Something widely accepted by the scientific community is that the presence of Fusarium toxins significantly potentiates the damage caused by mycotoxins traditionally recognized as more toxic, such as Aflatoxin, Ochratoxin, and T-2 toxin.
Determining which mycotoxins cause damage in poultry production
Determining which mycotoxins cause damage is ideally one of the first steps to consider before choosing an anti-mycotoxin additive. Identifying characteristic lesions facilitates this task, since most mycotoxins affect specific target organs. For example, T-2 toxin, HT-2, or DAS can produce mouth ulcers, unlike Aflatoxin, which affects the liver and/or causes bruises in the skin and muscles. Under commercial conditions, most companies decide which product to include after evaluating feed mill analyses and, in some cases, reports of negative effects on performance. For farms that can identify which mycotoxins are affecting their flock through macroscopic or histopathological evaluations, this information allows them to select products with proven efficacy against the specific toxins present. Since more than one mycotoxin is generally present in the ration, combining two types of mycotoxin binders is sometimes necessary to achieve a broader spectrum of protection.
Although testing for mycotoxins in feed is a very practical way of finding out which ones are present, there are certain limitations to this tool. Results can vary due to the uneven distribution of mycotoxins in the samples analyzed, regardless of the laboratory technique used, whether simple tests such as ELISA (well known for its limited sensitivity) or more sophisticated methods such as HPLC (high-performance liquid chromatography) or LC-MS/MS (Liquid Chromatography-Tandem Mass Spectrometry).
Anti-mycotoxin solutions
Over the years, various anti-mycotoxin feed additives have been developed, including the following:
Traditional clays represent the first generation of products developed for aflatoxin control. Some clays can adsorb other mycotoxins in addition to aflatoxin, but their spectrum of action is not as broad as that of purified clays.
Purified clays are modified and activated through specialized processes — many are identified as organo-clays. Within this group, some have demonstrated efficacy in experimental trials against difficult-to-capture mycotoxins such as ZEA, as well as T-2 toxin and FUM.
Products containing bacteria, yeast cell walls, enzymes, and/or algae are frequently combined with clays. Some manufacturers claim that the microorganisms present can metabolize mycotoxins and convert them into less toxic metabolites.
How to evaluate mycotoxin binders?
Considering the large number of products available in the global market, the following are key factors to consider before deciding which additive to use.
1. In vitro test
A preliminary test and essentially a quality control measure. If a product clay works in vitro, it does not mean that it works in vivo. The test consists of determining the adsorption capacity of a product against different mycotoxins using HPLC at two pH levels (3.0 and 6.0), simulating the conditions of the gastrointestinal tract. Under no circumstances should the decision on which product to use be based solely on in vitro testing, it must always be accompanied by animal testing. The inclusion rate recommended in the feed should be the same as that used in this test.
2. In vivo test
When conducting this type of test, it is necessary to measure performance (body weight gain, feed intake, feed conversion, and target organ protection). For example, if the efficacy of a product against aflatoxin is being measured, its effect on the liver must be quantified. If a product is evaluated against T-2 toxin, the effect of the anti-mycotoxin additive on oral lesions must be assessed. Although T-2 toxin causes damage through direct contact due to its causticity when ingested, an effective additive will reduce the degree of oral lesions through its adsorption capacity in the intestines. Some mycotoxins, such as FUM, do not cause macroscopic damage to the chicken liver, so it is necessary to measure biomarkers such as sphingosine and sphinganine, which are produced by the toxic effect of FUM on sphingolipid metabolism in blood. The dose recommended under commercial conditions should be the same as, or close to, the one tested in vivo. When evaluating additives containing substances that act as growth promoters (yeasts, enzymes, immune stimulants), their effectiveness should not be based solely on favorable performance results.
3. Detection of markers/metabolites in blood
Metabolites of emerging mycotoxins such as Beauvericin, and other toxins such as Tenuazonic acid, are measured in blood and reported to poultry growers as indicators of mycotoxin exposure. Based on the scientific literature reviewed, the importance of these newer mycotoxins has not yet been established in commercial poultry production. For commercial farms fed with DON-contaminated feed, metabolites such as Deoxynivalenol-3-sulphate have been measured before and after using a mycotoxin binder.
4. Identification of lesions at the slaughterhouses
This tool demonstrates whether an anti-mycotoxin additive is working properly once it has been included in the diet. Every week, examine at least 200 to 300 birds at the slaughterhouse, looking for mycotoxin-associated lesions in the carcasses. To further support this evaluation, it is ideal to periodically submit formalin-fixed tissue samples for histopathological assessment.
Conclusion
It is critical to determine what type of mycotoxins are affecting the birds in order to decide which binder to include in the feed. Once an anti-mycotoxin additive has been selected, slaughterhouse evaluations will supply critical information regarding the efficacy of the product chosen.
