Mycotoxins in Feed and Their Amelioration: A Review

JOURNAL OF ANIMAL NUTRITION AND PHYSIOLOGY Journal homepage: www.jakraya.com/journal/janp Mycotoxins in Feed and Their Amelioration: A Review MINI-REVIEW V.R. Patel., M. Choubey*, B.J. Trangadiya and A.P. Raval Department of Animal Nutrition, College of Veterinary Science and A.H., Navsari Agricultural University, Navsari 396450 (Gujarat), India. *Corresponding Author: M. Choubey Email: mahipalvet@gmail.com Received: 07/08/2015 Revised: 27/09/2015 Accepted: 29/09/2015 Abstract Mycotoxins are widely distributed among major feed ingredients, affecting animal production and performance. A part of ingested mycotoxin is being metabolized by rumen microbes and liver while remaining may affect the different organ system and may be excreted through milk and urine. They are produced in the field crops, during harvest, or during storage, processing, or feeding. They affect dairy cows by reducing feed consumption and nutrient utilization, altering rumen fermentation, suppressing immunity and reproductive performance. Diagnosis can be difficult because mycotoxin residues are not easily detected in the cow, and symptoms are often nonspecific and may be the result of a series of events or opportunistic diseases. There risk can be minimized or inhibited through various managemental techniques involving physical, chemical, microbiological and nutritional interventions, of which use of mycotoxin binder is most prevalent and viable under field conditions. Keywords: Mycotoxin, Feed, Amelioration. 1. Introduction Molds are filamentous (fuzzy or dusty looking) fungi that occur in many feedstuffs including roughages and concentrates. They can infect dairy cattle, especially during stressful periods when they are immune suppressed, causing a disease referred to as a mycosis. Molds also produce poisons called mycotoxins that affect animals when they consume mycotoxin contaminated feeds. This disorder is called a mycotoxicosis (Upadhaya et al., 2010). Mycotoxins can be formed on crops in the field, during harvest, or during storage, processing, or feeding (Katole et al., 2013). Molds are present throughout the environment. Spore concentrations are high in the soil and in plant debris, and lie ready to infect the growing plant in the field. Mold growth and the production of mycotoxins are usually associated with extremes in weather conditions leading to plant stress or hydration of feedstuffs, to poor storage practices, low feedstuff quality, and inadequate feeding conditions (Patil et al., 2014). It is generally accepted that the Aspergillus, Fusarium and Penicillium molds are among the most important in producing mycotoxins detrimental to cattle. The mycotoxins of greatest concern include: aflatoxin, which is generally produced by Aspergillus mold; deoxynivalenol, zearalenone, T-2 Toxin, and fumonisin, which are produced by Fusarium molds; and ochratoxin and PR toxin produced by Penicillium molds. Several other mycotoxins such as the ergots are known to affect cattle and may be prevalent at times in certain feedstuffs. There are hundreds of different mycotoxins which are diverse in their chemistry and effects on animals. It is likely that contaminated feeds will contain more than one mycotoxin (Whitlow and Hagler, 2004). 2. History In the early 1950 s, death of cattle on consuming moldy corn was reported in the United States (Sippel et al., 1953). Toxic substances from Aspergillus and Penicillium fungi were identified to cause the problem in later years (Burnside et al., 1957). The toxin responsible for the mortality was first purified by British scientists (Allcroft et al., 1963) from peanut meal originating in Brazil and was then named aflatoxin. Mycotoxins are toxic secondary metabolites produced by fungi (molds) that cause undesirable consequences (mycotoxicosis) when animals are exposed. Worldwide, approximately 25% of crops are affected by mycotoxins annually (CAST, 2003), which would extrapolate to billions of dollars (Trail et al., 1995). The study of mycotoxins began in 1960 with the outbreak of Turkey X disease in the U.K. (Sargeant et al., 1961). 3. Mycotoxin Prevalence

Mycotoxins are ubiquitous in nature; however, geographic distribution of mycotoxin has diverse variation with respect to their occurrence (Lawlor and Lynch, 2005). Contamination of feed with mycotoxins accounts for significant losses in dairy industry as well as an undesirable trade barriers for raw materials and consumable products. The worldwide prevalence of mycotoxins in feedstuffs and feeds was carried out by Rodrigues and Naehrer (2012) to detect the presence of mycotoxins like aflatoxins (AF), deoxynivalenol (DON), zearalenone (ZON), fumonisins (FUM) and ochratoxin A (OTA). They found that the AF and OTA were more prevalent in countries having subtropical and warm temperate climates (Table. 1) such as India, Pakistan and Bangladesh where 83% and 67% of analyzed samples tested positive for these mycotoxins, respectively (Table 1). On qualitative analysis of collected cattle feed samples across the Gujarat state by Fulsoundar and Shukla (1978) revealed that more than 60% samples were positive for aflatoxins. Among positive samples, 100% samples were found positive for AFB1 followed by AFG1 (Table 2). On quantitative analysis the amount (ppm) of Aflatoxin in the cereal by products and compound cattle feed sample were 0.95 to 6.50 and 0.89 to 3.31, respectively which were much higher than the permissible limit. As per the reports of Narasimhan and Muthumary (2008), 77% of commercial feed samples in Tamilnadu state have shown the presence of mycotoxins, which were positive for AFB1, AFB2 and OA. Compound cattle feed in Pakistan revealed a high incidence for aflatoxin B1 (97.3%) followed by B2 (50.3%), G1 (10.7%), G2 (1.5%), zearalenone (39.3%), ochratoxin A (37.5%) and deoxynivalenol (2.9%) with average values of 29, 8, 21, 10, 862, 64 and 813 ng/g, respectively (Sultana et al., 2013). Sarathchandra and Muralimanohar, (2013) have reported the high occurrence of citrinin followed by AFB1 and ochratoxin A in feed stuffs and feeds in Tamilnadu and the level of mycotoxins was found 20-350, 50-80 and 20-160 µg/kg, respectively. On ingestion of mycotoxin contaminated feed, the secondary metabolite of mycotoxin could be excreted in milk and thereby contaminate milk product also. Rastogi et al., (2004) reported that the incidence of milk product contamination of AFM1 could be of the magnitude of 87.3%. The range of contamination of AFM1 was comparatively higher in infant milk products (65 1012 ng/l) than liquid milk (28 164 ng/l). Almost 99% of the contaminated samples exceeded the European Communities/Codex Alimentations recommended limits (50 ng/l), while 9% samples exceeded the prescribed limit of US regulations (500 ng/l). 4. Toxic Effect of Mycotoxins Fungal pathogens include Aspergillus, Penicillium and Fusarium has been proposed as the pathogenic agent associated with mycotic hemorrhagic bowel syndrome (HBS) in dairy cattle (Puntenney et al., 2003). Healthy cows with an active immune system are more resistant to mycotic infections as compared to dairy cows in early lactation, which are immune suppressed (Kehrli et al., 1989). 4.1 Aflatoxins (AF) Aflatoxins are a family of extremely toxic, mutagenic, and carcinogenic compounds produced by Aspergillus favus and A. parasiticus. AFB1 from feed after metabolism in animals body is excreted in milk in the form of AFMI. The FDA limits aflatoxin to no more than 20 ppb in lactating dairy feeds and to 0.5 ppb in milk. Symptoms of acute aflatoxicosis in mammals include: inappetance, lethargy, ataxia, rough hair coat, and pale, enlarged fatty livers. Symptoms of chronic Aflatoxin exposure include reduced feed efficiency and milk production, jaundice, and decreased appetite. 4.2 Deoxynivalenol (DON) or Vomitoxin Deoxynivalenol is a Fusarium produced mycotoxin that is one of the most commonly detected in feed and is associated with range of disorders including feed refusals, diarrhea, emesis, reproductive failure, and deaths. The impact of DON on dairy cattle is not well established, but clinical data showed an association between DON contamination of diets and poor performance in dairy herds (Whitlow et al., 2004). 4.3 T-2 Toxin T-2 toxin is a very potent Fusarium produced mycotoxin that occurs in low (<10%) proportion of feed samples (Russell et al., 1991). It is associated with reduced feed consumption, loss in yield, gastroenteritis, intestinal hemorrhage, reduced reproductive performance, bloody diarrhea, low feed consumption, decreased milk production and absence of estrus cycles in cows and death. 4.4 Zearalenone (ZEA) Zearalenone is a Fusarium produced mycotoxin that has a chemical structure similar to estrogen and can produce an estrogenic response in ruminants including vaginitis, vaginal secretions, poor reproductive performance and mammary gland enlargement of virgin heifers and abortions (Kellela and Ettala, 1984). 29

Table 1: Prevalence of mycotoxins in south Asia (India, Pakistan and Bangladesh) Parameters AF ZON DON FUM OTA No. of tests 188 185 174 188 186 % positive 83 35 24 62 67 Average (ppb) 90 32 61 380 15 Median of positive 38.0 53.0 139.0 443.0 4.1 Maximum (ppb) 2454 1099 1330 6196 1582 (Rodrigues and Naehrer, 2012) Table 2: Qualitative aflatoxins analysis of cattle feed samples in Gujarat Feed samples % positive Aflatoxin (AF) B1 B2 G1 G2 Oilseed cake (50) 64% (32) 100 16 56 3 Cereals and damaged grain (13) 69% (9) 100 0 22 0 Cereal byproducts (33) 22% (7) 100 0 14 0 Compound cattle feed (8) 63% (5) 100 0 40 0 (Fulsoundar and Shukla, 1978) 4.5 Fumonisin (FUM) Fumonisin B, produced by E verticillioides, was first isolated in 1988. It causes leucoencephalomalacia in horses and is thought to be a promoter of esophageal cancer in humans (Chu and Li, 1994). Fumonisin is associated with reduced feed consumption and milk production in dairy animals. 4.6 Ergot alkaloids One of the earliest recognized mycotoxicoses is ergotism caused by a group of ergot alkaloids. They are produced by several species of Claviceps. Ergotism primarily causes a gangrenous or nervous condition in animals. Its symptoms are directly related to dietary concentrations and include reduced weight gains, lameness, lower milk production, agalactia and immune suppression (Robbins et al., 1986). 5. Diagnosis of Mycotoxicosis In spite of recognition of the impact of mycotoxins on animal production, they are a bit difficult to diagnose and identify. The progression and diversity of symptoms are confusing, making their diagnosis complicated. The difficulty of diagnosis is increased due to limited quantum of research, occurrence of multiple mycotoxins, non-uniform distribution, interactions with other factors, and problems of sampling and analysis. 6. Biotransformation of Mycotoxin in Rumen Ruminal degradation of mycotoxin helps to protect the cow against acute toxicity, but may contribute to chronic problems, associated with long term consumption of low levels of mycotoxin. A number of microbes from different niche have been reported to have biotransformation ability. Biotransformation or cleaving and detoxifying mycotoxin molecules by microbes or enzyme is effective and safer method of mycotoxin control strategy (Raju and Devegowada, 2000). The ruminants are more resistant to mycotoxin poisoning than monogastrics (Kurmanov, 1977). The first mycotoxins shown to be detoxified by ruminants were ochratoxin A (Hult et al., 1976) and AFB1 (Allcroft and Carnaghan, 1963). Upadhaya et al. (2010) reported that AFB1 degradation in rumen fluid was influenced by the species of animal and types of forage fed to the animals. The degradation products are generally less toxic than parental molecules. Biodegradation of mycotoxins with microorganisms or enzymes is considered as the best strategy for detoxification of feedstuffs. 7. Excretion Following oral administration, urinary excretion is most efficient way to eliminate mycotoxins which 30

are strongly absorbed and metabolized, such as AFB1, citrinin, OTA, PAT and ZEN. Faecal excretion results from a lack of absorption by the gastrointestinal tract or a highly efficient elimination of toxins or their metabolites by the biliary system. (Galtier, 1998). The excretion of toxins and their metabolites in milk represents another route. AFB1, OTA, ZEN and their metabolites, particularly AFM1, can represent a potential risk to the consumer due to their carryover in cow s milk (Whitlow et al., 2000). 8. Sampling and Analyzing Collection of representative feed samples is a problem, because molds can produce large amounts of mycotoxins in small areas, making the mycotoxin concentrations highly variable within the lot of feed (Vasanthi and Bhat, 1998). Toxin determination may be carried out by thin-layer chromatography plates, high-performance liquid chromatography, gas liquid chromatography, enzyme-linked immunosorbent assays, and spectrophotometer or by other techniques. Black lighting for bright-greenish-yellow fluorescence (BGYF) is often used as a screening technique for aflatoxin in corn grain; however its precision is under question. 9. Prevention of Mycotoxicological Risk in Animals The control of mould growth involves maintaining the physical integrity of cereal grains with the aim of limiting the access of moulds to nutrients present in the grains, and the strict control of environmental conditions such as water content, oxygen concentration and temperature. Drying is thus an essential step in the preservation process of dry feed, and anaerobiosis is a prerequisite to the storage of feed in a moist form. 9.1 Physical Methods Manually sorting out contaminated grains by the physical aspect of grains or by fluorescence to detect the presence of some mycotoxins, have been used. Other toxin inactivating techniques have also been proposed like high temperature, UV, X-rays or microwave irradiation, and solvent extraction of toxins (Scott, 1998). 9.2 Chemical Methods A variety of chemical agents such as acids, bases (ammonia, caustic soda), oxidants (hydrogen peroxide, ozone), reducing agents (bisulphites), chlorinated agents and formaldehyde, have been used to degrade mycotoxins in contaminated feeds, particularly aflatoxins (Scott, 1998). The addition of binding agents able to fix mycotoxins may reduce the bioavailability of these compounds in animals. In the case of AFB1, hydrated sodium calcium aluminosilicates (HSCAS) and phyllosilicates derived from natural zeolites have a high affinity, both in vitro and in vivo. 9.3 Microbiological Methods Certain strains of lactic acid bacteria, Propionibacteria and Bifidobacteria have cell wall structures that can bind mycotoxins (Yoon and Baeck, 1999) and limit their bioavailability in the animal body. Glucomannans extracted from the external part of the cell wall of the yeast Saccharomyces cerevisiae are able to bind certain mycotoxin (Devegowda et al., 1998). 9.4 Dietary Management Increasing dietary levels of nutrients such as protein, energy, dietary fiber, buffers and antioxidants may be advisable (Galvano et al., 2001). Because mycotoxins reduce feed consumption, feeding management to encourage intake can be helpful. Transition rations can reduce stress in fresh cows and reduce effects of mycotoxins. Strategic use of mold inhibitors could also be beneficial. 9.5 Mycotoxin Binders The addition of mycotoxin binders to contaminated diets has been considered as the most promising dietary approach to reduce effects of mycotoxins (Galvano et al., 2001). The theory is that the binder decontaminates mycotoxins in the feed by binding them strongly enough to prevent toxic interactions with the consuming animal and to prevent mycotoxin absorption across the digestive tract. Potential absorbent materials include activated carbon, aluminosilicates (clay, bentonite, montmorillonite, zeolite, phyllosilicates, etc.), complex indigestible carbohydrates (cellulose, polysaccharides in the cell walls of yeast and bacteria such as glucomannans, peptidoglycans, and others), and synthetic polymers such as cholestryamine and polyvinylpyrrolidone and derivatives. 10. Future Prospects Future step in this direction must encourage research activities lead to the development of new products that are more efficient on a larger range of mycotoxin without limiting the availability of nutrients and micronutrients in animals. Considering the impact of mycotoxins on animal and human health along with 31

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