Mycotoxins in oats: effects on animal production and methods of analysis

Animal diets include a combination of feedstuffs designed not only to meet their nutritional requirements at the lowest possible cost, but also to ensure their health, welfare, and production performance.

Cereals are one of the most common ingredients in feed formulation, as they provide most of the essential nutrients for livestock.

⇰ Among the most used cereals in the feed industry are corn, wheat, barley, sorghum and oats¹.

Oats (Avena sativa L.) is a crop of great importance, especially in countries of the northern hemisphere.

It is traditionally used for animal feed, although its human consumption has increased considerably in recent years due to its outstanding nutritional and multifunctional properties².

Oats are susceptible to contamination by various fungal species, both in the field and in post-harvest storage.

These fungi can damage grain structure, reducing grain quality and yield.

Moreover, many of these fungal species can produce toxic secondary metabolites, known as mycotoxins, which pose a risk to animal and human health³.

MAIN FUNGI AND MYCOTOXINS IN OATS

Fusarium

Fusarium is the most common mold on oats and it is responsible for the disease known as “Fusarium Head Blight”.

The production of its mycotoxins is strongly influenced by climatic conditions and therefore varies according to the growing region⁴.

The most relevant Fusarium mycotoxins in oats include:

• Zearalenone (ZEN)
• Fumonisins (mainly B1)
• Trichothecenos tipo A and B

Among type A trichothecenes are T-2, HT-2 and diacetoxyscirpenol (DAS) toxins are noteworthy.

Among type B trichothecenes are deoxynivalenol (DON) and nivalenol (NIV). In addition, some glycosylated forms, such as DON-3-glucoside (DON-3-G) and T-2-glucoside, may be present^5,6,7,8.

Studies in Sweden, Finland, Poland, Norway, Canada, and Spain have shown increased contamination by DON and its derivatives (15-acetyl-DON, 3-acetyl-DON, and DON-3-G), ZEN, NIV, and fumonisin B1 (FB1)^{7,9,10,11,12,13}.

On the other hand, in countries such as the United Kingdom, Ireland, Czech Republic and Switzerland, type A trichothecenes and their glycosylated forms are predominant, due to the variability in the Fusarium species present in each region^5,6,14,15.

Emerging Fusarium mycotoxins, such as enniatins, beauvericin, fusaric acid and fusarenon-X, can also be detected in oats.

⇰ Studies in the Republic, Sweden, and Ireland have identified a significant presence of beauvericin and enniatin B, correlated with high levels of NIV^5,10,14.

Alternaria

Alternaria mycotoxins have been less studied, but have also been found in oats and may pose a health risk.

These include¹⁶:

• Alternariol (AOH)
• Alternariol monomethyl ether (AME)
• Tentoxin (TEN)
• Tenuazonic acid (TeA)

The content of AOH in oats has been found to be higher than that of other cereals such as wheat and barley.

Likewise, the content of TEN is high in oats, similar to that of wheat, and its combination with TeA is frequent

Penicillium and Aspergillus

Penicillium and Aspergillus mycotoxins often appear in oats after harvest.

Penicillium mainly produces ochratoxins, such as ochratoxin A (OTA) and ochratoxin B (OTB), while Aspergillus can also produce ochratoxins, although it is best known for producing aflatoxins.

However, these mycotoxins rarely reach levels of concern in oats used in animal feed^5,7,19.

Sterigmatocystin, an emerging mycotoxin produced by Aspergillus, has occasionally been detected in oats, although at low frequency⁵.

MYCOTOXIN REGULATION IN ANIMAL FEED

Limits and recommendations for mycotoxins in feed are established in various European Union (EU) directives and recommendations:

• Commission Directive 2003/100/EC of 31 October 2003 amending Annex I to Directive 2002/32/EC of the European Parliament and of the Council on undesirable substances in animal feed.

• This includes a maximum limit for aflatoxin B1 (AFB1) in these products²⁰.

• Commission Recommendation of August 17, 2006, on the presence of DON, ZEN, OTA and fumonisins in products intended for animal feed^21.
• Commission Recommendation of 4 November, 2013, amending Recommendation 2006/576/ EC as regards T-2 and HT-2 toxins in feed²².
• Commission Recommendation (EU) 2016/1319 of 29 July, 2016, amending Recommendation 2006/576/ EC as regards DON, ZEN, and OTA in pet food²³.

In EU legislation, only the limits established for AFB1 are mandatory, while the levels of DON, ZEN, OTA, T-2 and HT-2 toxins, and the sum of FB1 and FB2 are considered recommendations.

IMPACT OF MYCOTOXINS ON ANIMAL PRODUCTION

Fusarium and Alternaria mycotoxins are the most common mycotoxins in oats and can be present in feed products made from oats, affecting the health and performance of livestock.

Fusarium mycotoxins

Type A trichothecenes

Type A trichothecenes, such as T-2 and HT-2 toxin, are highly toxic to animals.

T-2 toxin, in particular, causes:

• Reduction of food consumption
• Weight loss
• Oral necrosis
• Internal hemorrhages in pigs and poultry
• Damage in the gastrointestinal tract

In addition, it can cause immunosuppression, increasing susceptibility to infections, and can affect milk production in cows.

HT-2 toxin, although somewhat less toxic, also interferes with protein synthesis and affects immune function and animal growth, which may decrease productive efficiency²⁴.

Type B trichothecenes

DON and NIV are the main type B trichothecenes.

DON, known as “vomitoxin”:

• Is widely recognized for inducing vomiting and feed refusal in pigs, which causes a decrease in weight gain.
• Reduces feed efficiency and impairs immune response, increasing susceptibility to infections.
• Alters the intestinal barrier, facilitating the entry of pathogens.

NIV, although less toxic than DON, also reduces growth in pigs and poultry and alters intestinal function, increasing the risk of infections and other digestive problems²⁴.

ZEN

ZEN is a mycotoxin with estrogenic activity that can cause reproductive disorders in animals, especially in pigs.

Its toxicity is due to its ability to bind to estrogen receptors, generating endocrine, immunotoxic and carcinogenic effects.

In females, it causes:

• Hyperestrogenism
• Infertility
• Vulvar enlargement
• Abortions

In males, it:

• Reduces semen quality
• Affects testicular development

Reproductive problems have also been described in cattle and fish, where it reduces fertility, affects growth, and can accumulate in muscle^25,26.

Fumonisins

Fumonisins, especially FB1, interfere with sphingolipid metabolism, causing:

• Leukoencephalomalacia in horses and pulmonary edema in pigs.
• Hepatic and renal damage in various species.
• Possible carcinogenic effects and metabolic alterations.
• Hepatic and renal involvement in fish, where they reduce growth and feed consumption, alter feed conversion and may cause lesions in the brain and pancreas.

Alternaria mycotoxins

These mycotoxins have genotoxic, mutagenic, and carcinogenic effects in humans and animals²⁸.

⇰ Prolonged exposure may increase the risk of chronic diseases and affect DNA integrity.

TeA is a potent inhibitor of protein synthesis and is considered more toxic than AOH and AME.

It can cause alterations in cell metabolism and reduce feed efficiency in animals.

Although its toxicity in mammals is relatively low, TEN is a toxin that affects chloroplast development in plants.

Its impact on animals is minor compared to other Alternaria mycotoxins²⁹.

Emerging mycotoxins

Emerging mycotoxins recently detected in oats, such as NIV, DAS, enniatins, beauvericin, fusaric acid, fusarenon-X and sterigmatocystin, can have a variety of adverse effects on animal health.

These mycotoxins have the potential to affect the gastrointestinal and reproductive systems, feed conversion efficiency and can induce inflammatory processes.

METHODS OF ANALYSIS OF MYCOTOXINS IN OATS

Mycotoxin analysis in oats is essential to ensure food safety and compliance with current regulations.

Accurate detection of these compounds is a challenge due to their low concentration, heterogeneous distribution, and the presence of conjugated forms^8,31.

Screening methods

These methods allow rapid and preliminary detection of mycotoxins in oats.

They are used to evaluate large sample volumes and provide rapid results, although with lower precision than chromatographic methods. These include^1,32:

• ELISA (Enzyme-linked immunoadsorbent
  assay): widely used method due to its speed and ease of use.

• It is applicable for the detection of mycotoxins such as DON, ZEN, and OTA. However, it may present interferences with the sample matrix, which affects the accuracy of the result.

• Biosensors: they incorporate antibodies or aptamers that allow the detection of mycotoxins through optical or electrochemical signals.

• They are an emerging technology with the potential to improve the speed and specificity of analysis, although they require more extensive validation before routine use.

• Lateral flow devices: these are fast and portable detection tools, ideal for analysis in the field or in emergency conditions.

• They work by detecting mycotoxins in a sample, generating a visual signal (as a colored line) on a test strip. Although they are fast and easy to use, their sensitivity and accuracy can be inferior to more advanced methods, so they are generally used for initial screening.

Chromatographic methods

These methods offer greater accuracy and specificity in the detection of mycotoxins, although they require specialized equipment and longer analysis time^1,32.

• High performance liquid chromatography (HPLC): technique widely used in the determination of mycotoxins.

• It is used with UV, fluorescence detectors (FLD) or coupled to mass spectrometry (MS), allowing the simultaneous detection of multiple mycotoxins. Its main advantage is the accuracy and sensitivity of detection.

• Gas chromatography (GC-MS): mainly used for volatile mycotoxins or those requiring prior derivatization.

• Although it offers high sensitivity, its application is more limited due to the complexity of the analytical procedure.

Non-invasive methods

New techniques are currently being explored for the detection of mycotoxins in oats without the need for destructive sample preparation^33,34,35,36.

An example of this is near infrared spectroscopy (NIR).

This technique allows the detection of mycotoxins quickly and without sample destruction, which makes it ideal for real-time analysis.

However, it requires specific calibrations and may be affected by matrix variability, which limits its applicability in some cases.

CONCLUSION

Monitoring and control of Fusarium and Alternaria mycotoxins in oats for animal feed is critical, as their presence can affect the health and performance of livestock.

The choice of analysis method depends on factors such as the type of mycotoxin, the required sensitivity, and the available infrastructure.

While screening methods such as ELISA, lateral flow devices and biosensors allow rapid and preliminary detection, chromatographic techniques remain the gold standard for their accuracy and ability to detect multiple mycotoxins.

The development of new technologies, such as advanced biosensors and spectroscopic techniques, opens new possibilities for improving the speed and accessibility of analysis.

As these tools evolve, their integration into automated systems will facilitate more efficient control.

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