DON, understanding of its various intestinal modes of action.
Mycotoxins, molecules produced by molds, contaminate 25% of grains intended for humans and animals worldwide. At certain doses, mycotoxins are responsible, among other things, for weight loss in farm animals. Additives with anti-mycotoxin properties are marketed, but not very effective on deoxynivalenol (DON). DON is one of the mycotoxins particularly affecting pigs which also has an impact on the response to viral infections (SRRP). In order to validate the protective impact of an anti-mycotoxin compound on the weight gain of pigs, the researchers want to quantify meticulously the use that the animal will make of the nutrients it ingests, namely the digestibility of the nutrients in pigs. receiving DON.
The small intestine is a long organ (on average 6 m), its section following the stomach is used to absorb nutrients and contains few microorganisms compared to the colon or large intestine. The colon is colonized by an important microbial flora called the microbiota. This region notably helps to complete the breakdown of food, maintain the water balance of the pig, absorb molecules made by the microbiota, eliminate certain toxins and protect against pathogens. Currently, researchers are more and more interested in the colon because it is involved in the modulation of the immune response and in neurological exchanges with other organs (inflammatory response, control of satiety).
A multidisciplinary team from Laval and Montreal Universities has precisely measured the digestibility of nutrients in pigs exposed or not to DON and subjected or not to an anti-mycotoxin additive coupled to an antioxidant mixture. The experiments carried out on six castrated pigs highlight a different action of DON depending on the intestinal region analyzed.
During the experiment, DON increased the absorption of nutrients in the ileal part but the measurements covering the entire intestinal tract show that in the end the total digestibility decreased for dry matter and energy; thus corroborating the work of other research teams. DON is therefore absorbed quickly, but its main action could be due to its impact on the colon microbiota (previously shown). Like the weight change models correlated with the microbiota in rats and between human twins, one can imagine that the modulation of the microbiota by DON would influence the satiety of pigs who eat less lose weight.
Most feed additives are not effective against DON, however the use of sodium bisulfite coupled with antioxidants (SBS-O) is able to reduce the impact of DON on the weight gain of pigs, possibly by transforming DON in the DON-sulfonated form which is less toxic. The CRIPA-FRQNT team therefore also checked this impact on the digestibility of nutrients. The SBS-O additive had no impact on the total digestibility of the nutrients, even if it reduced their absorption at the ileal level. SBS-O also reduced absorption of DON without completely preventing it. Interestingly, SBS-O in the presence of DON also modifies the fermentation process of the colon microbiota, an impact that remains to be studied.
The scientific community has shown that the microbiota can produce molecules that have a targeted impact on certain pathogenic microbes. In particular, it has been shown for Salmonella and Candida albicans, that a molecule produced by the microbiota can modulate the aggressive functions of these pathogens which then colonize the intestine without causing disease. It would therefore be very interesting to better characterize the modifications of the microbiota in order to find how to increase the protective action of SBS-O in this anti-DON approach.
Source: Mélina Josiane Bouchard, Younes Chorfi, Marie-Pierre Létourneau-Montminy & Frédéric Guay (2019) Effects of deoxynivalenol and sodium meta-bisulphite on nutrient digestibility in growing pigs. Archives of Animal Nutrition, 73:5, 360-373, DOI: 10.1080/1745039X.2019.1641369
