Mycotoxins are secondary fungal metabolites and are of great concern worldwide. It is estimated that 25% of the world's cereals are contaminated with mycotoxins. There are several methods that have been used to detoxify or inactivate feeds that have been contaminated with mycotoxin, but they are extremely unstable or impractical. First, the damage of mold on feed Since the outbreak of X-disease in the UK in 1960, the world began to pay attention to the thorough investigation of toxin poisoning. More than 300 fungi are known to produce toxins, but in addition to several toxins, little is known about the toxins they produce. The important toxins that are known are: aflatoxin, ochratoxin, citrinin, and zearalenone. These molds are distributed differently and have been separated from a wide variety of cereals and mixed feeds. Fungal growth: Aspergillus is a member of the Aspergillus family and most fungal contamination events occur during improper handling of harvest, transportation, feed ingredients, and mixed feed storage. Feed moisture content of 12% or more, relative humidity of 80 to 90% and temperature of 10 to 42°C are sufficient for the growth of fungi. The molds cause serious damage to the feed. Microbial activity is the main cause of mildew in stored feeds. Individual micro-organisms are extremely small, and they are often not easily detected before they multiply. When a mildew color is found, it indicates that the microbiology reproduction is already in an exuberant stage and the feed quality has been severely damaged. 1, causing a lot of nutrients. According to research, molds that cause moldy feeds are a kind of saprophytic microorganisms. Not only does the microbe not produce nutrients itself, but it can often decompose feed nutrients by secreting various enzymes for its growth and reproduction. Therefore, the content of nutrients in feeds contaminated with mold is greatly reduced, and an unpleasant musty odor is emitted. The Food and Agriculture Organization of the United Nations (FAO) surveys that about 10% of the total amount of cereals, oilseeds and feeds that are contaminated by fungi each year in the world. It can be seen that mold is a major hazard that affects the development of agriculture, feed and aquaculture all over the world and must be highly valued. 2, cause fever, so that storage material qualitative change. As molds consume feed nutrients, they also release heat. As a result of the increase in feed temperature, protein, fat, and vitamins in the feed are changed. First, the protein undergoes a qualitative change, resulting in a decrease in protein solubility, a decrease in pure protein, an increase in ammonia nitrogen, a decrease in protein utilization, and an amino acid content. 3, produce toxin pollution feed. In this article, emphasis is placed on the contamination of mycotoxins with grains and feed and their possible detoxification methods. Mycotoxins are secondary fungal metabolites and are still an area of ​​great concern worldwide. Mycotoxins, if any, are usually found in agricultural products in the form of trace contaminants in concentrations ranging from nanograms to micrograms per gram. The intense research on mycotoxins has been going on for nearly 40 years. In 1961, the first group of mycotoxins was isolated and described. They consist of aflatoxins. This is the result of a study of severe acute diseases that broke out in animals in 1960. In 1965, following the discovery of aflatoxin, another group of important mycotoxins (Ochratoxins) was identified. Second, the mycotoxin classification and the risk of mycotoxin poisoning are typically due to the occurrence of acute clinical symptoms. These acute poisonings have obvious manifestations and can cause economic losses, but more often it is difficult to detect hidden poisoning. The biological and economic consequences of acute poisoning are much smaller than those of latent poisoning. One example is the general production performance and suppressed immune status caused by lower doses of mycotoxins. This situation is particularly noteworthy because the Food and Agriculture Organization of the United Nations estimates that 25 percent of the world's cereal supply is contaminated with mycotoxins. Animal experiments have shown that mycotoxins can cause heart rate slowdown, rapid breathing, hair removal and miscarriage. In terms of mycotoxins, there are mainly Aspergillus, Penicillium and Fusarium contaminated feeds. According to reports, the detection rates of 121 livestock and poultry feedstuffs in dozens of feed factories and farms in six regions in Hunan Province were 76.2% and 55.4%, respectively, for Aspergillus flavus, Aspergillus niger, Aspergillus parasiticus, and Aspergillus niger. 49.6% and 20.6%. For the 66 samples of corn, rice bran, soybean meal, fish meal, rapeseed meal, and cottonseed meal, the mold contamination rate was 89.4%. The main place where fungi produce mycotoxins could be in the field (“field toxins†such as zeoctolin), also It can be a warehouse ("storage toxins" such as aflatoxins and scorpion toxins), or both. The presence of mycotoxins in crops or feed depends on many factors such as: crop type, crop susceptibility, type of attached fungi, insect or mechanical damage, sterilization at harvest, storage conditions, and subsequent Any treatment. The most important mycotoxins are briefly discussed below and, if possible, information on tolerability and regulations is attached. Hesseltine (1986) ranks the relative importance of mycotoxins (and their major target sites) around the world as follows: Aflatoxins (hepatotoxins) Scorpionotoxins (nephrotoxic toxins) Xylosporins (skin toxins) Zearalenone (Estrogen) Deoxynivalenol (skin toxin). Naturally produced plant toxins In addition to toxins produced by various fungi, naturally occurring plant toxins (anti-nutritional factors) are also involved in animal nutrition. Some important, but sometimes misunderstood, non-mycotoxins are: Glucosinolate and sinapic acid, which are found mainly in rapeseed. Gossypol, a polyphenolic compound, is found in certain seeds of the cotton genus. Lupin alkaloids, the total alkaloid content of new lupin varieties, are generally lower than 0.03%. Aflatoxins Among various toxins, aflatoxins are considered to be the most toxic because they can cause hepatotoxicity, mutations, Carcinogenesis and immunosuppression. No other toxin has such a wide range of toxicity as aflatoxin, so the world has more knowledge of it, and aflatoxin is a product of fungi, Aspergillus, Aspergillus flavus, and the like. They produce aflatoxins B1, B2, G1, M1, M2. Among them, B1 is the most toxic. Aflatoxins are a very toxic group of chemicals that are mainly produced by Aspergillus flavus A. parasiticus. These Aspergillus are widely distributed in the air and soil around the world, and both dead and living animals and plants can infect. In the tropical and subtropical regions, the highest incidence of aflatoxin appears in food and feed. The hot and humid climate there provides the best conditions for fungal growth. For example, the optimum temperature for Aspergillus flavus is 28-30°C and the minimum moisture content in peanuts is exactly 8-10%. Among many contaminated agricultural products, peanuts, cottonseeds, and rice are the most susceptible to aflatoxin-producing molds. Due to the widespread appearance of aflatoxin, they cause serious economic losses to livestock production. For example, it was estimated that the direct economic loss caused by weight loss in 1986 due to broilers eating feed contaminated with aflatoxin was approximately $140 million. A large number of reports have reported that Aspergillus flavus can cause hepatotoxicity, but it also affects the entire system of the individual, causing macroscopic and histological changes, affecting growth and productivity, and eventually causing an increase in mortality. In addition, in addition to mutagens and carcinogens, Aspergillus flavus can also affect the immune system, causing poultry to increase susceptibility to many infectious diseases. In the case of chronic poisoning, except for a slight decrease in productivity, the clinical symptoms are not very obvious and therefore difficult to diagnose. Given that aflatoxin is an important harmful feed pollutant, strict regulations have been established to limit its maximum content in feed and food. For example, according to the US Food and Drug Administration (1988), the highest level of aflatoxin in corn is 20 μg/kg (for humans and dairy cows), 100 μg/kg (for poultry), and 200 μg/kg (for Finishing pigs) and 300 μg/kg (for beef cattle). The European Union stipulates that the maximum content of aflatoxin in agricultural products from January 1, 1999 is generally 4 μg/kg, while the highest content of aflatoxin B1 (the most toxic compound) is 2 μg/kg. * Scorpion Toxin Scorpionotoxin is the most important storage poison in warm areas. In the tropics and subtropics, scorpion toxin A is mainly produced by Aspergillus and in warm regions it is mainly produced by Penicillium, especially Penicillium viridicatum. P. viridicatum can even be at a minimum temperature of 4°C and wheat at low moisture content. Under 18.5% conditions, the most common derivative of saxitoxin A (OA) is produced. When these conditions are not met, the fungus can grow but does not produce toxins. OA can even be detected in randomly selected human milk samples from Germany and Sweden. The main sources of human intake of OA are cereals and their products. In a recent large-scale survey conducted in Denmark, 1431 samples of wheat, barley, rye, oats, and bran were analyzed. The results showed that 40% of samples were contaminated with OA. In the products analysed, the OA contamination of the bran was higher than the grain part of the grain. For example, OA was detected in 62% of wheat bran samples, and only 30% of wheat samples were detected in OA. This is the case with most mycotoxins, where the content of mycotoxins in cereal by-products (especially bran) is higher than whole grains. The production of OA in cereals is mainly during the first period after harvest, when the activity of water has not been reduced by drying. Therefore, the most important way to prevent OA is to ensure good agricultural practices and prevent fungi from starting to grow and produce toxins during agricultural production and processing of agricultural products. Scorpion toxin A is a very carcinogenic toxin. According to reports, 0.2 to 0.3 mg of scorpion toxin A per kilogram of feed can poison pigs. The susceptibility of ruminants is much smaller because the microorganisms in their rumen will degrade toxins. The World Health Organization recommends (1991) that the general maximum limit per kilogram of grain and its products is 5 micrograms. Some countries (including Denmark and Sweden) also regard this as the legal maximum limit. * Fusarium Toxin It has been found that DON is present on all cereals, which is a type of dexamethasone. The most affected seems to be wheat. The main symptom of pigs after eating a feed containing more than 0.7 mg of DON per kilogram was that of feeding, but vomiting was rarely observed. Even toxic effects can occur with only 0.25 mg DON per kilogram of feed. Pigs are the most sensitive animals. The U.S. Food and Drug Administration's veterinary center has recently set a limit of 4 milligrams per kilogram for animal feed, provided that the feed does not exceed 10% in pig or pet diets, and no more than 50% in other animal feeds. . Zearalenone is a mycotoxin that occurs predominantly on corn. Its main function is similar to that of estrogen, and it has been determined that it can cause reproductive problems in pigs. This effect can be caused by a concentration of 1 mg/kg in the diet. It was found that the daily intake of 60 micrograms of zearalenone per kilogram of body weight could have an unobservable negative effect on the reproductive performance of pigs. The U.S. Food and Drug Administration Veterinary Center has not regulated the level of zearalenone action in feed. * Rototin: Rotoxin is a group of mycotoxins recently discovered in South Africa and therefore has not been listed before. Rototin is produced by Fusarium moniliforme and F. porliferatum of the genus Fusarium. The latest literature states that rotitoxin is a ubiquitous toxin, especially in corn and its products. The most toxic component of rotten horse toxin is rotoxin B1, and the most sensitive animal is the horse. Rotten horse toxin can cause serious adverse effects such as leukomalacia in equids and pulmonary edema in pigs. At present, research is being strengthened on this group of mycotoxins, especially in the United States. Other mycotoxins of regional significance are Alternaria toxins and ergot alkaloids. Alternaria toxins are produced by the genus Alternaria, which are microorganisms that cause many fruits and vegetables to spoil after harvest. Although ergot alkaloids are uncommon, they are still present in cereal products, especially in developing countries. Analysis and Detoxification In recent years, there has been a lot of accumulated information on mycotoxin production, mechanisms of action, and their impact on livestock and poultry production. The immediate need is to understand how to use mycotoxins contaminated feed in livestock and poultry diets. Many toxins are thermally stable and can survive granulation and other processing. Many toxins are not antigenic. In addition to aflatoxins, the pathology, clinical effects, acute and chronic toxicity effects, and diagnostic knowledge of these toxins are still limited. The mycotoxin safety limit is a disagreement with regard to the safety limit of toxic effects of Aspergillus flavus. Various suggestions "safety level" from 20ppb to 2000ppb. One of the reasons for this widespread existence is that many studies only use death as a criterion for safety margins. However, poultry farming does not just keep chickens alive, but it requires chickens to produce meat or eggs. The European Community listed 20 ppb as a significant level. This limit is limited by two well-defined parameters. Permissible levels of aflatoxin should not: (1) affect animal health and production; (2) be high enough to pass through animal products into the human food chain. Simply analyzing the safety of single mycotoxins can greatly underestimate the real dangers facing livestock and humans. Many factors such as genetic variation, animal nutrition status, environmental stress, age, and gender can affect aflatoxins. Therefore, as a concept, security is often based on limited personal experience. It has been stressed that it is impossible to have a safe level of toxins because even very small doses may prove to be prolonged to cause canceration over long periods of time. 1. Analysis Most mycotoxins can be quantitatively analyzed by high-pressure liquid chromatography (HLPC). Unfortunately, most feed mills and food factories cannot perform this analysis. Recently, many studies have reported semi-quantitative rapid analysis using microcolumn screening or enzyme immunoassay. Although some caution is used in interpreting this test result, especially if it is used to test complex samples, these test methods can still provide a good basis for predicting the existence of certain mycotoxins. 2. Decontamination Technology It is estimated that mycotoxins can affect 40% of the world's food crops and produce toxins in metabolic processes. The presence of toxin-producing fungi in crops does not mean that they have been infected by toxins, but as long as toxin fungi are present, it means potential catastrophes. Moreover, molds or toxins are rarely present alone, and the combined toxicity of two or more toxins may be greater than that of any single toxin. Killing these fungi can stop the toxin from continuing to produce, but it cannot remove the toxins that it produces. Therefore, the biggest challenge in dealing with contaminated feeds is to quickly determine the type and concentration of toxins. The main method of preventing toxins from toxins is the use of feed additives and various enzymes. 3. Control measures The toxicity level of many mycotoxins is only formed under certain environmental conditions. Therefore, fungal growth and mycotoxin production should be prevented as much as possible to minimize the harmful effects of these toxins. However, some environmental conditions are difficult to control. For example, in 1998, the summer of Europe was wet and cold, and the growth of field fungi was greatly increased, causing the grain to be seriously contaminated by Fusarium toxins. Therefore, methods that may be used to detoxify food and raw materials to ensure the safety of food supplies are being extensively discussed. There are many approaches that have been used to detoxify or inactivate mycotoxin-contaminated feeds, such as physical separation, heat inactivation, radiation, microbial degradation, and treatment with various chemicals. Chemicals used to test their ability to degrade and inactivate mycotoxins include various acids, bases, hydrogen sulfates, oxidizing agents and gases, as well as silages. With the exception of ammoniating, most methods are impractical, ineffective, expensive, or potentially dangerous. Even for ammoniation, the competent authorities and the research department have different opinions. For example, in the United States, only Arizona, California, and Texas allow ammonium treatment of aflatoxin-contaminated cottonseed meal products. Texas also allows the ammoniation of corn contaminated with aflatoxin. However, the Food and Drug Administration prohibits any interstate transportation of aflatoxin-contaminated but aminated cottonseed or corn because of the lack of evidence for the safety of amination reaction products. In short, there is currently no safe and inexpensive detoxification treatment of mycotoxin-contaminated feed. The first type of decontamination effort is the use of liquid extraction methods such as organic solvents, calcium chloride or aqueous sodium bicarbonate solution or saline. Ammonia treatment and monomethylamine and calcium hydroxide may also be effective. In high humidity conditions, high heat or high heat and high pressure can also destroy toxins. However, this treatment differs depending on the type of toxin, the heating time, the temperature, and the water content in the feed grain. Some toxins, such as aflatoxin, trichosporine, zeolicin, chloramphenicol, patulin, etc., are highly stable, but often exist in wheat and rye alkaloids and citrinin It is very easy to destroy. Ultraviolet and plasma emissions are also effective in destroying toxins such as aflatoxin, but they also destroy nutrients in feed ingredients. The ammonia treatment of aflatoxin is the most commonly used and most effective method in practice. 4, the use of feed additives in the prevention of feed pollution often encounter some practical difficulties, taking into account the cost and the time spent, attention has gradually focused on adding feed additives in the feed. These feed additives can fight mycotoxin in the body. Some mineral complexes can be absorbed and digested by the body, but not harmful to the body. These complexes are often referred to as feed additives. For example, mineral clays such as activated carbon, yeast cell wall products and bentonite, sodium sepiolite have such abilities to varying degrees. The absorption of mycotoxins from the gastrointestinal tract is reduced by the addition of adsorbed substances to the feed. Materials tested were charcoal, zeolite, bentonite, certain clays, and cholestyramine. Although some positive results have been achieved in scientific research, there are also huge differences of opinion in the discussion on the use of these substances. For example, the study group of Kubena et al. found that several sorbents protect pigs from aflatoxin toxins ranging from 0 to 75%. As mentioned earlier, there is currently no safe and stable antimycotoxin feed additive. Some of the synthetic products in use are zeolite, vanadium, and gamarabinobutanoic acid (GABA). Zeolites are effective against aflatoxins, T-2 toxins and vomitomycin but their effects are non-specific and the binding to many toxins is often incomplete. Adding 2% of zeolite per kilogram of feed containing 1 mg of aflatoxin B1 reduces the toxin level in the liver by 30 to 40%. Adding 0.20% methionine to the mixed feed can significantly reduce the effect of zeolite. This may also be a possibility that medicine can reduce the ability of toxins to bind. The body of livestock and poultry absorbs and decomposes toxins, which reduces the energy exchange rate of the body. Adding some additives to feed normalizes energy exchange. For example, in the case of low toxin concentrations, the addition of GABA or its analogues or sulphate acid can prevent the decline in productivity and normalize the energy conversion; if the toxin intake concentration is high, these additives will weaken the toxin effect. Addition of GABA to each kg of diet containing 1 mg of Aspergillus flavus can very well prevent the toxin effect, but it cannot completely eliminate the effect of antitoxin in the diet of 2 mg of Aspergillus flavus per kilogram. Adding silico-alumina to the feed also effectively absorbs aflatoxins and to some extent absorbs zearalenone and trichothecenes. Mycotoxins differ greatly in their structural and physical properties. For example, the family of triflumin alone consists of more than 100 derivatives. It is therefore obviously impossible to develop a method that can be applied to several different mycotoxins. Furthermore, animal feed is a complex matrix that may contain many interfering substances. There is also evidence that certain adsorbents may have a negative effect on important nutrients. As to why the efficiency of aflatoxin binding is much higher than that of other mycotoxins, one can first compare the following molecular structures. The molecular structure of these compounds is very different. According to observations, aflatoxin differs from other mycotoxins in two ways: (1) it has a relatively strong, rigid, almost uniplanar, atomic structure; (2) it is the only one that contains a 1,3-diketone structure. molecular. Although deoxytetrazol and T-2 toxins also have a relatively rigid molecular structure, the cup-shaped structure of their molecules makes them less coplanar. The partial structure of zearalenone is homogenous (ie, their phenolic ring), but other parts of these molecules are very "relaxed." Fusarium toxin is completely non-rigid, although it has a polar structure that may react quite strongly with clay surfaces. 5. The mycotoxin added to the blood to supplement methionine is detoxified by the liver. The biodegradation and oxidation of aflatoxin in the liver is based on glutathione. Part of glutathione is methionine and cystine. Therefore, this process will consume methionine, affecting growth and production performance. Therefore, when feed is affected by aflatoxin contamination, it is recommended to add more methionine. 6. The use of enzymes New developments in mycotoxins have included the use of enzymes to help break down toxins. The current knowledge is that most mycotoxins can be biotransformed by microsomal oxidation in the liver, so people are using enzymes that enhance mycotoxin metabolism (monooxygenase inducers). These enzymes degrade toxins Poisonous metabolites These metabolites are low in toxicity and are easily excreted from the body, reducing the toxin concentration and toxicity of toxins in the liver.Some enzymes can make zearalenone, T-2 toxin, deoxynivalenol Inactivation of alcohols, etc. Endolipase can break the zearalenone internal alicyclic ring, and the cyclooxygenase degrades the trichothecene enzyme toxin 12, 13 epoxy group, by splitting the mycotoxin functional atom group, the enzyme These toxins degrade into non-toxic metabolites, and non-toxic metabolites can be digested without causing side effects.To sum up, we often don't want to throw away human consumption, and we have to use livestock and poultry diets. Controlling the risk of contaminating the diet is one of the most important ways to solve this problem recently. There are many technologies that can reduce toxicity; * Establish a mycotoxin monitoring program * The first line of defense against fungal infections is agriculture. Infection with mold and toxins in the medium, proper harvesting, drying, and storage of grains to eliminate the favorable conditions for the production of toxins in the storage.* Physical separation of harmful or fungal infections of grains or seeds is basic general knowledge. Diet, dilute toxin-containing grains with clean grains to increase nutrient content in the diet.* Add anti-mould agent to prevent further infection of the feed.86 * Use feed additives to reduce feed toxicity. * One of the most recent methods is to use enzymes. * The addition of methionine above 30%-40% of the NRC standard can reduce the toxic effects.Finally, the best way is to prevent fungal growth through agricultural and technical means. Another possible approach is to feed certain animals. The harmful effects are diluted, for example by mixing so that the content of a certain kind of mycotoxins in the finally obtained mixed feed is below a dangerous level, and a mixed feed containing some mycotoxins may also be used to feed animals with lower sensitivity. For example, ruminally contaminated feed is fed to ruminants instead of monogastric animals.
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