Feed contamination by mycotoxins remains a big issue and the use of “in the feed” solutions to limit their adverse effects on animals is essential. A wide range of products is available on the market, with different mode of action and level of efficacy. With new challenges facing the feed industry, it will be crucial to evolve from basic toxins binder to more comprehensive and elaborate solutions.
MYCOTOXINS: A WIDESPREAD ISSUE AND FUTURE CHALLENGES
Mycotoxins are secondary metabolites, with low molecular weight, toxic in nature and naturally produced by various species of fungi, mainly Aspergillus, Penicillium and Fusarium which usually contaminate food and feed ingredients. They represent a very diverse group, with more than 400 different recognized mycotoxins that differ from each other structurally and in their toxicity. Their prevalence is high worldwide, with recent data reported, for usually detected mycotoxins, up to 60–80% contaminated crops, largely higher than the 25% estimated by the Food and Agriculture Organization (FAO) a few years ago. It is also well admitted that a very high percentage of cereal-based animal feed is contaminated with more than one mycotoxin, the major contaminants being Fusarium mycotoxins such as deoxynivalenol (DON), zearalenone (ZEA) and fumonisins (FBs). Only a low percentage of feed samples is contaminated above permitted or guideline levels. However, animals (poultry, fish and pigs particularly) exhibit symptoms of mycotoxicosis even when exposed to feed contaminated with mycotoxins below the guidance levels, probably as a consequence of negative synergistic effects.
With climate changes and better knowledges about mycotoxins contamination and toxicity, feed industry will have to deal with new challenges to cope with mycotoxins issues to maintain optimal animal health, well-being and performance. The challenges to consider are:
– the unavoidable mycotoxins prevalence that increases globally;
– the threat due to new, emerging mycotoxins or metabolites that can be more toxic than parent molecules;
– and the admitted, but poorly known, rule of multi-contamination that can exacerbate the effects of individual mycotoxins.
IMPACT OF MYCOTOXINS ON ANIMAL HEALTH AND PERFORMANCE
The mycotoxins of most concern in animal nutrition, due to their toxicity and occurrence, are aflatoxins, deoxynivalenol, ochratoxin, zearaleone, fumonisin and T-2 toxins. These can have various effects from chronic syndromes, with reduced productivity, impaired gut function or increased predisposition to infectious diseases and, less frequently, acute toxicoses with severe illness and death. The degree of toxicity that these compounds exert on the animal’s body is complex and depends primarily on the type of mycotoxin, their amounts, the duration of exposure, the overall health of the animal, sex, age, race, and many other factors.
DIFFERENT STRATEGY TO ALLEVIATE MYCOTOXINS EFFECTS IN ANIMAL
Due to hazardous and ubiquitous nature of mycotoxins contamination, different strategies are usually used to limit their negative effects on animal.
• Decrease the biovalaibility of mycotoxins through adsorption, biotransformation / biodegration – In vitro results
The aim of such solutions is to prevent or minimize exposure of animals to mycotoxins by reduction of mycotoxin uptake as well as distribution to the blood and target organs by decreasing their bioavailability in the gastro-intestinal tract. Adsorbing agents also called binding agents, adsorbents, binders, can be silica-based inorganic compounds, such as bentonites, montmorillonites, zeolite… or carbon-based organic polymers such as some complex indigestible carbohydrates (cellulose, polyssacharides from the cell walls of yeasts or bacteria). They are large molecular weight compounds that should be able to bind the mycotoxins in contaminated feed without dissociating in the gastrointestinal tract of the animal. In this way the toxin-adsorbing agent complex passes through the animal and is eliminated through faeces. A wide diversity of compounds has been reported for mycotoxins binding, especially for aflatoxins, however all of these products are not equivalent considering their level of efficacy, their activity spectrum, their interaction with other essential nutrients or their quality in terms of contaminants (dioxins, heavy metals, …), specially for clays-based products. Figure 1 shows variable levels of efficacy of some binding agents (clays, Yeast-cell wall) toward different mycotoxins.
Since multi-mycotoxin contamination is a topic of great concern and that synergic interactions between mycotoxins but equally with other biotoxins such as endo or exo-toxins, are more and more documented as exacerbating the adverse effects on animal, the rigorously selection and combination of the most efficient adsorbing agents, can allow maximum protection against challenges posed by broad-spectrum mycotoxin and bacterial toxins contamination.
An alternative strategy to deactivate mycotoxins in animal feeds is the use of microorganisms or enzyme systems having the capability to detoxify mycotoxins by metabolisation or degradation prior to their resorption in the gastro-intestinal tract. Indeed, this approach can be a specific, irreversible and environmentally friendly way of detoxification because it leaves neither toxic residues nor undesirable by-products.
Zearalenone (ZEA) and their derivatives metabolites are amongst main mycotoxins that require particular attention and interests to manage using biotransformation or biodegradation. Zearalenone has been shown to negatively affect the reproductive function of pigs and other animal species due to estrogenic effects. Indeed, it fits to the estrogen receptors triggering the wrong hormonal responses and upsetting the reproductive system. Interestingly, it has recently shown that effects of their derivatives can be up 60 times more toxic than parent ZEA molecule. Animals can be exposed to these derivatives through naturally contaminated feeds but equally after metabolization of zearalenone in environments with other micro-organisms such as the gut or he rumen.
A recent example for high degradation potential has been shown with Bacillus strains that were able to degrade zearalenone and their main metabolites, with levels up to 99.9% degradation using in vitro conditions, i.e ZEA at 1 ppm, initial Bacillus strains inoculum at 6 log CFU/mL and optimal incubation assays (pH7, 30°C, 24h) (Figure 2). These results, comforted in different other oxygen conditions, pH and temperature, also highlight the Bacillus potential efficacy in various physico-chemical and physiological environment (all along the digestive tract) and in different animal species.
• Support global animal health by bioprotection effects – In vivo results in piglet
Through the term bioprotection, it can be found a wide variety of action mechanisms and also numerous types of compounds. Bioprotection can be defined as all physiological action mechanisms that can support animal global health from mycotoxins negative effects. It can be antioxidant, immunostimulatory agents or specific amino acids or other molecules that can allow liver, gastro intestinal tract, kidneys, and other organs to function without interference from toxin. It can also involved compounds that strengthen the intestinal barrier and tight junctions, thus limiting the transfer of endotoxins or (emerging) mycotoxins into the organism.
For example, in pigs, deoxynivalenol is known to affect immune response and impaired gut health, by reducing the proliferation of enterocytes and the intestinal surface, resulting in impaired weight gain. Due to this chemical structure, DON is also well known to be poorly managed by adsorption strategy.
A trial performed on 32 piglets per group, with 21 days post-weaning piglets supplemented by Bacillus strains for 21 days and receiving 0.9 mg DON/Kg of complete feed, has shown that Bacillus significantly limit the passage of DON in serum (Figure 3). Since these bacteria didn’t show evidences neither for adsorption, nor for biotransformation/biodegradation effects in vitro, the prevalent hypothesis was their bioprotection effects, as largely well-documented in literature data through their ability to reinforce tight junctions of the gut barrier to limit the mycotoxins, specially DON, transfer into the organism. This bioprotection effect was associated with improvement of animal performance, with an increase of weight gain between days 14-21 of + 64 g (+8%) (p value = 0.09). Mean weight gain (g/D) were 720 and 784, for contaminated DON control group and supplemented group, respectively.
The best strategy to counteract the adverse effects of biotoxins on animals: to combine complementary actions – In vivo results in poultry
Considering the ubiquitous presence of multiple mycotoxins, their different levels and also the diversity of other environmental and stresses that animal have to cope in their production cycle, especially with the presence of other biotoxins such as bacterial toxins, the best strategy to counteract the adverse effects of toxins on animal is to combine complementary actions. Based on this principle, the MiXscience premium product Multiprotect Up, is an association of carefully selected ingredients, including Bacillus strains, that allow to combine multiple mode of action, such as adsorption, biotransformation and bioprotection properties. In different production context, it has demonstrated its ability to support animals coping with naturally, low and multiple mycotoxins challenge through different animal species contributing also to their better health and performance.
In broilers, a study was performed in Ivory Coast, with locally raw materials naturally challenged with mycotoxins, mainly aflatoxins, fumonisins (FB1 and FB2) and deoxynivalenol with levels up to 0.8, 1.7 and 0.05 mg/Kg of finished feed, respectively. Compared to the control group, in supplemented group, body weight was significantly increased (+ 60g; +3%), the final mortality of the animals was reduced, and blood analysis showed a significant decrease in aspartate aminotransferase levels at D21 (Figure 4), indicating a better liver health. The improvement of performance and a significant decrease of mortality (Figure 5) has equally been demonstrated in a duck commercial farm in Vietnam. The trial was performed with a total of 23 440 animals, divided in 2 groups and receiving for 46 days, naturally challenged local feed containing with DON and T2 Toxin at levels of 0.5 mg/Kg and 39 µg/Kg, respectively.
With growing evidence, there is no more doubt that the presence of mycotoxins is practically unavoidable in feed and that its management remains key because of significant threat to animal health, productivity and sanitary issues that can occur. The complementary effects resulting from the association of ingredients specifically selected to face these various animal challenges, make it possible to combine multiple modes of action in the gut and in the global organism such as mycotoxins adsorption, biodegradation and animal bioprotection, and contribute to better animal health, well-being and performance.
About Dr. Clarisse Techer
Clarisse Techer obtains a Msc degree in Microbiology at the Rennes 1 University (Fr) in 2009. After this period, she worked on the impact of dietary fiber in piglet feed and on the establishment of sensitive and specific immunological methods for the detection of staphylococcal enterotoxins in dairy products. In 2012, she joined the Animal nutrition and processing domain of the Avril group (Fr) and undertakes PhD research in the joint research unit “Science and Technology of Milk and Egg” between Agrocampus Ouest and the National Research Institute for Agriculture, Food and Environment (INRAE). Her PhD work concerned the control of spoiling bacteria in refrigerated food composed of egg products. Since 2015, she works in the Department of Research, Innovation and Development (RID) of MiXscience (Avril group) as researcher in microbiology and then as RID manager. Her main current research interests include animal gut health management, search for alternative solutions to the use of antibiotics in animal feed and mycotoxin risk management.
About Anne-Laure Tournay
Graduated with an Agricultural Engineering Master’s degree, Anne-Laure Tournay has a solid experience in marketing acquired within various international agricultural companies. She started working as a product manager for the world’s leading equipment manufacturer for dairy farming, responsible for the Cow Comfort range for the Southern European market. From 2016, she held the position of international product manager for a veterinary laboratory, in charge of the Hygiene range for all animal species. She joined MiXscience in September 2019 as In Feed Solution Product Manager. She is in charge of the development and marketing of two solutions portfolios: the Rabbit range, and the Multiprotect range dedicated to issues related to biotoxins.