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MYCOTOXINS IN THE FEED Are you ready and prepared for their destructive effects?
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by Radka Borutova and Olga Averkieva, Business Development Manager, Nutriad International
ycotoxins are secondary metabolites of low molecular weight produced by a wide range of fungi, principally moulds. There are over 200 species of moulds that produce mycotoxins. Aflatoxins (Afla), zearalenone (ZEN), ochratoxin A (OTA), fumonisins (FUM), trichothecenes such as deoxynivalenol (DON), and T-2 toxin are some of the mycotoxins that can significantly impact the health and productivity of poultry species. Mycotoxins are unavoidable contaminants in foods and feeds and are a serious problem all over the world. The number of mycotoxins known to cause signs of toxicity in mammals and birds is increasing. Feed is the most important source of mycotoxins. Fungal growth and subsequent mycotoxin formation is dependent on a range of factors including seasons, location of grain cultivation, drought and time of harvest. Long-term analysis of grain and feed samples worldwide has indicated that it is possible to have grains with extremely high concentrations of mycotoxins, although the overall mycotoxin contamination is low (Streit et al., 2013a). This data also revealed
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that mycotoxin contaminated grains typically contain more than just a single mycotoxin. Mycotoxins produce a variety of diseases, collectively called “mycotoxicoses,� directly or in combination with other primary stressors such as pathogens (Raju and Devegowda, 2000). Acute mycotoxicosis outbreaks are sporadic events in modern poultry production. Nevertheless, low or undetectable levels of mycotoxins are responsible for reduced performance and increased susceptibility to infectious diseases. The problem is even more complex since in many cases, the molecular mechanisms of their action have not been fully explained.
Mycotoxins cause increased oxidative stress in organisms
Biochemical changes during mycotoxicosis can vary significantly and lipid peroxidation is regarded as one of the key effects of mycotoxicosis. It is not clear whether mycotoxins stimulate lipid peroxidation directly by enhancing free radical production or if the increased tissue susceptibility to lipid peroxidation is a result of decreased antioxidant protection. It is likely that both processes are involved. An effect of mycotoxins on lipid peroxidation in vivo has been reported by a number of authors. Many mycotoxins are lipophilic substances and are readily absorbed into the membrane, resulting in structural alteration within the membranes. The alteration triggers the stimulation of membranous lipid peroxidation. Ochratoxin A, T-2 toxin, fumonisins and Afla were shown to have pro-oxidant properties. There are also data available indicating pro-oxidant properties of ZEN and citrinin. In most cases, lipid peroxidation in tissues caused by mycotoxins was associated with decreased concentrations of natural antioxidants in blood serum, liver and ovary.