Abstrakt

DON is the most common mycotoxin in swine feed. It is found in corn and cereals infected with fungi of the genus Fusarium. There are restrictions on the amount of DON in pig feed, as even small amounts negatively affect the productivity of animals. Therefore, a lot of research has been done on how to measure and mitigate the effects of DON and other mycotoxins, such as aflatoxin and zearalenone (ZEN). To date, several hundred mycotoxins with very different chemical structures have been identified. 

Latest findings - impact on swine health 

In a 2021 review of research on DON and other mycotoxins, Dr. Sung Woo Kim of North Carolina State University and colleagues concluded that the effects of these compounds on pigs include immune modulation, disruption of intestinal barrier function and cell death. "In our paper published in May 2021, we found that the consumption of DON by pigs altered [brain biochemistry] and caused an increase in passive and calm behavior," Kim says. DON was also shown to damage the gastrointestinal tract of the pigs tested due to a "direct toxic effect."

Recent studies on piglets have shown that when DON, ZEN and their derivatives are transferred from the diet of sows into the bodies of suckling piglets through colostrum and milk, the piglets' performance is not altered, but an inflammatory process takes place in their bodies. Kim, based on his research with colleagues, notes that making sure the digestive system in young pigs is in good shape is an effective way to deal with the effects of DON. 

Latest findings - DON detoxification 

As for the feed itself, many strategies and feed additives have been studied for their ability to reduce or mitigate the effects of DON and other mycotoxins. In a new review published in January 2022, researchers from Huazhong Agricultural University in China concluded that each strategy has advantages and disadvantages. 

Strategies include: 

- Physical detoxification (separation, washing, heating, irradiation, and adsorption) 

- Chemical treatment (alkalis and oxidizing agents) 

- Biological methods of detoxification (microorganisms and enzymes) 

- Nutritional regulation strategies (antioxidants such as vitamin E, selenium, and curcumin) 

However, the researchers note that many of the physical and chemical decontamination strategies that have been studied are limited in terms of binding efficiency, biosafety, or cost-effectiveness. 

This view is shared by Professor Piotr Jedziniak of the Department of Pharmacology and Toxicology at the National Veterinary Institute in Poland. "There are no effective adsorbents for DON due to its chemical properties," he says. "There is research on various biological agents that can degrade mycotoxins, such as microorganisms and enzymes, but in my opinion, the ability of biological additives is so far insufficient. They activate in the stomach and there are few experiments showing good efficacy. One of the reasons why there are few experiments is that animal tests are very expensive." 

Dr. Kim and his colleagues observed in their study that partial protection of the pig intestine can be achieved by adding enzymes and adsorbents to the diet. But, says Dr. Kim, "I was not sure whether the protective effect was due to enzyme activity or adsorbents." Like Prof. Jedziniak, Dr. Kim notes that although DON has been shown in laboratory tests to be inactivated by enzymes, evidence that it actually occurs in the pig intestine is limited. 

Organic and inorganic sources 

In their 2021 review, Dr. Kim and his colleagues also note that products currently on the market can combine organic and inorganic sources to enhance their adsorption, immune stimulation, or detoxification capacity - but the frequent co-contamination with mycotoxins in raw feeds and swine feeds makes detoxifying agents targeting multiple mycotoxins preferable. A recent study by researchers at the Prairie Swine Centre in Saskatchewan, Canada, also indicates the potential to mitigate the effects of DON by feeding higher concentrations of nutrients and antioxidants to promote overall health and counteract the effects of lower feed intake observed in the study. Recently, the results of a model study conducted by French researchers that focuses on the feed intake response of growing pigs to a diet contaminated with mycotoxins were published. They found that the age of the pigs and previous exposure to DON have little effect on "immune capacity" (the ability to cope with toxins in the feed). The researchers suggest that the degree of response to mycotoxin-contaminated feed (reluctance or less reluctance to take it) can be characterized in terms of "resilience and flexibility," and that "these traits may be a potential source of genetic selection for breeding animals with increased resilience."

Latest findings - actual exposure to DON

 While the amount of feed intake and its analysis have long been used to determine DON exposure, the amount of biomarkers found in blood plasma may provide more information. This is explained in a review by Prof. Jedziniak and his colleague Dr. Agnieszka Tkaczyk, published in August 2021, titled, "The Biomarkers of Mycotoxicosis. "Biomarkers of mycotoxins in pigs - current state of knowledge and analytics." First, Prof. Jedziniak and Dr. Tkaczyk note that among mycotoxins such as DON, which are produced when Fusarium fungi infect a corn plant, some DON is metabolized by the plant into other forms. "To date, a number of so-called 'modified mycotoxins' have been identified, and while not all of them are more toxic than DON itself, the level of toxicity of the toxic ones has not yet been established," says Prof. Jedziniak. "They may consequently contribute to higher toxicity, as has already been shown for 3- and 15-acetyl-deoxynivalenol (3- and 15-Ac-DON) and deoxynivalenol-3-glucoside (DON-3-Glc) in pigs and broiler chickens." Prof. Jedziniak adds that although there are currently no requirements for measuring levels of these modified mycotoxins in feed, the European Food Safety Authority recently recommended monitoring them. Prof. Jedziniak says that these modified versions "are increasingly being detected in feed analyzed for mycotoxins." This fact is not taken into account when exposure of pigs to toxins is determined in the traditional pattern of feed intake effects, and using routine feed analysis. Professor Jedziniak and Dr. Tkaczyk also note that toxins in feed can have a "highly heterogeneous distribution," leading to incorrect results during traditional feed analysis.

"Another problem is that feed analysis and measurements of feed intake do not provide data on individual exposure due to 'synergy' between animals - differences in the processes of food intake and absorption, metabolism, and excretion," explains Prof. Jedziniak. "Because of all these difficulties, animal exposure assessment can include a much broader analysis of toxin contamination in feed along with analysis of the amount of" biomarkers "in blood plasma to assess individual exposure to toxins." 

Biomarker analysis 

Although biomarker analysis is expensive because it involves mass spectrometry, by using it, the swine industry can gain many benefits in terms of DON mitigation. These benefits range from much more accurate insights into the effects of current, past, and cumulative exposure to mycotoxins, to much more efficient testing of various detoxicatins. Looking to the future, Prof. Jedziniak said: "It is impossible to produce corn without DON and other toxins, and there is no single solution that can be applied. "We need to make progress in breeding Fusarium-resistant corn, perhaps also in pig breeding, developing fungicides for crops, and studying various detoxifiers. New methods, such as measuring biomarkers, can provide much more information compared to traditional tools. "We need to continue research on Fusarium mycotoxins and biological detoxifiers such as probiotics such as Lactobacillus. These are destroyed during the high-temperature feed pellet manufacturing process, but perhaps they can be added to the diet in water. This is a very promising area to explore, but only some probiotics are currently available for animal use."