Ochratoxin A is a mycotoxin of great impact in poultry farming due to its effect on intestinal welfare and microbiota.

What are mycotoxins?

Mycotoxins are toxic secondary metabolites produced by some species of fungi. These microorganisms grow in the raw materials used to manufacture poultry feed. This process can occur both in crops and in the processes of storing and supplying feed to the poultry. Fungi produce mycotoxins that contaminate this feed, one of the most important is Ochratoxin A.

It is estimated that 25% of the world’s food and feed crops are contaminated with fungi. Therefore, the study of these fungi and their mycotoxins is currently of great importance to know how they impact the health of people and animals when they consume food contaminated with mycotoxins.

Importance of Ochratoxin A

Ochratoxins are a group of secondary metabolites produced by fungi of the genera Penicillium and Aspergillus. Among these, Ochratoxin A is the most toxic and common. It has been shown to have a nephrotoxic, hepatotoxic, teratogenic, and immunotoxic effect in poultry.

Ochratoxin A, also called OTA, has a strong binding capacity to 99% of circulating proteins such as albumin. This characteristic allows it to be absorbed more easily at the intestinal level by poultry.

Generally, young poultry is more sensitive to the effects of OTA than mature poultry. This is because young poultry has a digestive tract still in formation. In studies comparing the Lethal Dose 50 (LD50) it has been observed that comparing poultry with mammals, these production poultry are more sensitive against Ochratoxin A.

The maximum accepted limit of Ochratoxin A in poultry feed is 0.10 mg/kg in Europe.

The poultry digestive system

The poultry digestive system has multiple functions such as feed intake, digestion, nutrient absorption, and energy production, immune responses, and elimination of waste in feces.

The intestine is a tubular structure of several layers, which have specific functions:

• Mucosa: constitutes a large surface area for absorption of nutrients thanks to its villi and microvilli.
• Submucosa: is the portion containing the arteries, veins, inflammatory cells, lymphatic vessels, autonomic nerves, and ganglion cells.
• Muscular mucosa: is a thin layer of smooth muscle that generates peristaltic movements to move food contents.
• Serosa: made of connective tissue containing blood vessels, nerves, and fat. Each of these performs specific functions.

Intestinal epithelial cells block the entry of pathogens, toxins, and foreign antigens into the circulatory system. These intestinal epithelial cells are connected by desmosomes, tight junctions, and adherens junctions. These structures regulate intercellular space and paracellular activity related to ion transport.

Impact of Ochratoxin A on avian intestinal welfare

Ochratoxin A can have multiple pathological effects on the organs of production poultry. Intestinal welfare is a pillar in poultry farming since the digestive system has the function of absorbing nutrients supplied in the diet. Therefore, this organ processes and absorbs all nutrients to convert them into animal protein.

For this reason, it is of great importance to study the impact of mycotoxins on the digestive system. When there is damage in the intestine, production parameters are compromised, and the poultry’s welfare decreases. Among the most important effects of Ochratoxin A are:

Effect on nutrient absorption

It has been found that Ochratoxin A can inhibit glutamate absorption by decreasing the expression of the glutamate/aspartate transporter and the glutamate surface transporter, among other cellular transporters. Therefore, it is recommended to think that OTA generates physicochemical effects. This mycotoxin effect may increase the energy requirements of poultry.

Effect on the intestinal barrier

When poultry consume feed contaminated with Ochratoxin A, it was observed that the integrity of the intestinal barrier was deficient. The mycotoxin can destroy proteins that form tight junctions such as occludin or claudin-1. This leads to increased intestinal permeability, which favors the translocation of pathogenic bacteria from the intestinal lumen and facilitates the onset of systemic infection.

On the other hand, it has also been observed that in poultry ingesting OTA there are lesions in the intestinal villi, together with necrosis of epithelial cells. This may further reduce nutrient absorption and predispose to opportunistic infections as intestinal immune cells are affected.

The immune system is affected by Ochratoxin A.

A major systemic effect of Ochratoxin A is to cause immunosuppression with signs of nephropathy. OTA can reduce the lymphocyte population in the intestinal epithelium. In addition, OTA induces the secretion of proinflammatory cytokines such as IL-1B and Tumor Necrosis Factor a.

Likewise, it reduces the production of anti-inflammatory cytokines such as IL-19. Consequently, the intestinal villi are observed shorter, thinner, and with edema. This sum of events ends up increasing the permeability of the intestinal epithelium.

You may also be interested in: Innate immunity in poultry: what are its characteristics?

Effect of Ochratoxin A on the intestinal microbiota

The intestinal microbiota is a set of microorganisms that inhabit the digestive tract of poultry. This barrier represents an important component at the digestive level since it functions as a bridge between environmental substances and poultry metabolism.

A large portion of the mycotoxins such as Ochratoxin A that poultry ingests with feed is not absorbed. Instead, these toxins remain in interaction with the intestinal microbiota.

It has been found that at the colon level Ochratoxin A generates a loss of beneficial microorganisms such as Lactobacillus reuteri. In addition, at a general level, it decreases the diversity of the microbiota and may favor intestinal damage.

However, researchers in this area mention that more studies are needed on molecular signals such as transduction and metabolomics. In this way, it would be possible to better understand how Ochratoxin A generates and regulates intestinal injury in poultry.

Prevention of the effect of Ochratoxin A

The pathogenic effects of Ochratoxin A in poultry can be prevented with products that act against mycotoxins and improve intestinal welfare. Therefore, Alquermix LN combines Silicoglycidol and hepatic and intestinal conditioner pronutrients to prevent the pathogenic effects of Ochratoxin A.

Silicoglycidol is a mycotoxin binder that binds to these metabolites and prevents their action. In addition, this product contains hepatic pronutrients conditioners that optimize the metabolic functions of the liver and the regeneration of its cells. Secondly, intestinal pronutrient conditioners optimize the intestinal barrier cells, improving nutrient absorption and the rate of enterocyte regeneration. Thus, the intestinal welfare of poultry is enhanced.

Conclusions

Mycotoxins are secondary metabolites produced by some genera of fungi. Among these is the group of Ochratoxins generated by fungi of the genera Penicillium and Aspergillus. Ochratoxin A is the most important of this group.

It is recognized that ÂĽ of the world’s crops are contaminated with fungi and that poultry is among the animals most susceptible to Ochratoxin A contamination.

The poultry digestive system consists of a multilayered tubular structure, each one with broad functions. The intestinal welfare of poultry is altered when Ochratoxin A enters.

Ochratoxin A has effects on nutrient absorption, promotes the entry of microorganisms by increasing permeability, and can destroy the intestinal villi of productive poultry.

Finally, OTA can affect the intestinal microbiota which is a protective barrier against pathogenic bacteria. However, more studies about the pathological mechanisms on the microbiota are needed.