26.11.2020

Deoxynivalenol (DON) and intestinal inflammation in pigs

Dr. Hannele Kettunen, R & D Manager

The autumn is the time of harvest. The season brings the discussion and speculation about the quantity and quality of the crops. For an animal farmer, the concentrations of mycotoxins in cereal grains are of special interest.

Deoxynivalenol (DON), also called vomitoxin, is one of the most prevalent mycotoxins in cereal fields. This trichotecene metabolite of Fusarium fungi does not have a high acute toxicity, but it still causes several adverse effects such as nausea, loss of appetite, impaired immunity and decreased growth rate and reproductive functions in pigs and other farm animals. Due to the widespread occurrence of Fusarium fungi in grains, DON has been claimed to be the economically most important mycotoxin for the farm animal industry.

Mycotoxin binders do not help against DON

Aflatoxin B1, ochratoxin A, and zearalenone and some other mycotoxins readily bind to specific adhering agents such as yeast derivatives, clay or silicates which are added into feeds. These mycotoxin binders at least partly prevent the intestinal absorption of these mycotoxins, so that the toxins are retained in the intestinal lumen and become voided via feces.

This is not the case with DON. Deoxynivalenol escapes the action of mycotoxin binders, and quickly gets absorbed into the bloodstream. Means to control its absorption are scarce, so monitoring the levels in feeds is of outmost importance.

Pig are especially sensitive to DON

Pigs are the most sensitive farm animal species to DON. This is problematic, as cereal grains form such a large part of porcine diets. According to the European Union, the level of DON in complete feedstuffs should not exceed 0.9 mg/kg. As the name vomitoxin implies, DON gives a strong emetic response to pigs, causing decreased feed intake in mild cases or even a feed refusal when DON levels are high.

Currently, a complete understanding of all the factors that contribute to the sensitivity of pigs to DON does not exist, but its negative effects on the immune system and intestinal epithelium are likely involved.

DON activates proinflammatory cascades

After ingestion by a pig, DON is rapidly absorbed from the proximal small intestine, and reaches the peak plasma concentration as soon as in thirty minutes. In cells, DON attaches to the ribosomes, inhibiting the elongation step of protein synthesis and causing the cells to activate so-called “ribotoxic stress” responses (1). This process leads to proinflammatory immune activation. Eventually, DON is metabolized into several conjugated and modified forms, and excreted via urine.

DON harms gut barrier functions

Studies with pigs and pig cell lines have proven that DON harms the intestinal epithelial barrier functions, and causes gastrointestinal lesions and inflammation.  It has been demonstrated that the permeability of pig gut tissue to pathogenic E. coli is increases and the trans-epithelial electrical resistance decreases in the presence of DON (2).

Observations from in vivo studies lend support to the hypothesis. Thus, DON is clearly one of the many factors contributing to intestinal inflammation and dysbiosis in pigs.  

Progres® reduces inflammation and supports homeostasis in intestinal epithelium, regardless of the challenge factor

The delicate intestinal epithelium needs to absorb nutrients efficiently but keep the pathogenic bacteria of gut lumen away from the bloodstream. The gut tissue of pigs is constantly challenged by a variety of factors from pathogenic microorganisms to heat stress and feed-derived mycotoxins. The multiple stressors frequently cause small scale and local disturbances in the intestinal homeostasis.

Hankkija FFI’s resin acid -based feed material Progres® is known have anti-inflammatory effects in the intestine of monogastric farm animals. In-feed resin acids suppress the expression and activity of inflammation-associated, collagen-degrading matrix metallo-proteinases, and thus support gut barrier functions and intestinal homeostasis (3), regardless of the original challenge factor. Do not hesitate to ask your local distributor for more information on the benefits of Progres® on intestinal epithelium.

References

 

1) Pierron et al., 2016. Porcine Health Management 2:21.

2) Pinton et al., 2009. Toxicol Appl Pharmacol 237:41-48.

3) Aguirre et al. 2019. Vet. Res. 50:15.