Mycotoxin Issues in farm animals and strategies to reduce mycotoxins in animal feeds.

Mycotoxins are secondary metabolites produced by a wide array of diverse fungal species, mostly belonging to the three genera Aspergillus, Penicillium and Fusarium. They can be produced in the growing crop and during storage. Mycotoxin-contaminated feeds impair farm operations as well as feed production in various ways: mycotoxins are invisible, odourless and cannot be detected by smell or taste, but can reduce performance in animal production significantly. All species of livestock are affected by mycotoxins. Monogastrics (swine, horses) are most sensitive, followed by poultry and ruminants. In general, young stock and animals under environmental, nutritional and production stresses are most sensitive. Direct effects of mycotoxins include acute diseases, where severe conditions of altered health may exist prior to death as a result of exposure to the toxin. These conditions are more likely following exposure to high levels of a mycotoxin. Other, more insidious or occult conditions (e.g. growth retardation, reproduction troubles, impaired immunity, decreased disease resistance, decreased milk or egg production) or more chronic disease manifestations (e.g. tumor formation) may result from prolonged exposure to small quantities of a toxin. Mycotoxins display a diversity of chemical structures, accounting for their different biological effects. Depending on their structure, these toxins can be carcinogenic, teratogenic, mutagenic, immunosuppressive, tremorgenic, hemorrhagic, hepatotoxic, nephrotoxic, and neurotoxic. Diagnosis of mycotoxicoses in animals is difficult as they may be similar to diseases with other causations. This is even more difficult in cases where more than one mycotoxin is involved because the toxins can produce additive, and sometimes synergistic, effects in animals. In addition, the possible presence of toxic residues in animal product such as milk, meat and eggs may have some detrimental effects on human health. Considerable economic losses are attributed to reduced crop yields and grain quality following fungal contamination, to downgrading of cereals from human food grade to animal feed, and to decreased animal performance and increased incidence of disease in livestock consuming mycotoxin contaminated grain. Due to the modern methods and to a growing interest in this field of research more than 300 different mycotoxins have been differentiated to date. Mycotoxins commonly found in animal feed include aflatoxins (EFSA, 2004a), ochratoxin A (EFSA, 2004b), zearalenone (EFSA, 2004c), trichothecenes (e.g. deoxynivalenol) (EFSA, 2004d), fumonisins (EFSA, 2005), which differ in their toxic effects and their prevalence across regions. Aflatoxins cause liver damage and impaired immune function. Trichothecenes reduce feed intake and weight gain and, at higher concentrations, cause emesis and complete feed refusal. Fumonisin B1 is a carcinogen that is associated with equine leucoencephalomalacia, porcine pulmonary oedema, and spiking mortality in poultry. Zearalenone is an oestrogen that causes reproductive problems. Ochratoxin A is a nephrotoxin. Safe levels of mycotoxins in feed, below which there are no effects on animal health or production, are not well established. Regulatory officials world wide are very concerned about the presence of mycotoxins in food and animal feed. In the EU, two mycotoxins (aflatoxin B1 and rye ergot) are regulated (EC Regulation, 2002) under strict limits, while deoxynivalenol, zearalenone, ochratoxin A, T-2/HT-2, and fumonisins are subject to recommend guidance values (EC Recommendation, 2006). Use of feedingstuffs with levels above the maximum permitted is not allowed in the EU, neither the mixing of contaminated feed with non contaminated feed in order to reduce the concentration of my