Mycotoxins in animal feed: is there really a problem?
Published: October 3, 2007
By: E.M. Binder, E. Pichler, M. Kainz, V. Starkl
Our thanks to the author and Conference Organisers, a Committee consisting of both University and Industry colleagues.
The full paper will appear in the Conference Proceedings ('Recent Advances in Animal Nutrition - 2007', edited by Phil Garnsworthy and Julian Wiseman) published by Nottingham University Press in the autumn of 2007 www.nup.com
Courtesy of the 41st Annual University of Nottingham Feed Conference www.nottingham.ac.uk/biosciences/ah/research/conferences.php
Mycotoxins are secondary metabolites produced by filamentous fungi that can cause a toxic response (mycotoxicosis) when ingested by higher animals. Due to modern methods and thanks to a growing interest in this field of research more than 300 different mycotoxins have been differentiated so far.
However for a practical consideration in the feed manufacturing process only a small number of toxins is of relevance, with aflatoxins, trichothecenes, zearalenone, ochratoxins, and fumonisins being of particular interest, though it has to be mentioned that the extent of harm each toxin (group) can cause is highly species-dependant.
A three year survey program was initiated in order to evaluate the incidence of mycotoxins in feeds and raw materials in some of the major European animal production regions. Grain and feed samples were sourced directly at feed mills or animal production sites and sent to Quantas Analytik in Austria, where all analyses were performed by means of high performance liquid chromatography within the period of January 2004 to December 2006.
Mycotoxins tested for were those known for their impact on feed industry and animal husbandry: deoxynivalenol (DON), T-2 toxin, zearalenone (ZON), ochratoxin A (OTA), and aflatoxin B1 (AfB1). A total of 1838 samples sourced from European and Mediterranean markets was tested, with 3231 single analyses performed (1838 tests for DON, 943 ZON, 270 T-2 toxin, 109 OTA, and 71 AfB1, respectively).
In order to get a better overview about toxin occurrence in certain regions, data were grouped as follows: Northern Europe (Denmark, Belgium, Finland, UK, Norway, Lithuania, the Netherlands, Latvia), Central Europe (Romania, Poland, Slovakia, Ukraine, Hungary, Switzerland, Austria, Germany, Czech Republic), and Southern Europe and the Mediterranean region (Slovenia, Bulgaria, Portugal, France, Croatia, Spain, Greece, Turkey, Cyprus, Italy).
Highest incidence was observed with DON, which occurred in all commodities tested. Out of a total of 1838 samples 1162 were positive for DON, at an average contamination level of 380μg/kg. Levels (median and arithmetic mean) observed were slightly higher in Central and Southern Europe than in the North. Commodities mainly affected were corn, finished feed and wheat. 76% of all corn samples tested were positive for DON, with the overall contamination rate increasing from 59% in 2004, to 79% in 2005, and 90% in 2006. The median contamination level was 290μg/kg in 2004, 360μg/kg in 2005, and 604μg/kg in 2006, which indicates not only a very high incidence in 2006 but also high contamination levels.
A similar trend could be observed in finished feeds, with contamination rates of 56% (2004), 57% (2005), and 79% (2006), and respective median levels of 167, 214, 368 μg/kg. 74% of all wheat samples were positive for DON, though only in years 2004 and 2005 representative sample numbers were received; the median contamination levels were 284μg/kg and 370μg/kg, respectively.
With regard to ZON a total number of 943 analyses was performed, indicating an overall three year contamination rate of 34% (i.e. 320 samples positive). No particular difference in levels detected was observed with regard to sampling regions, except in 2006, when particularly Central European samples showed higher incidence (58%) and higher levels (mean: 220μg/kg, median: 100μg/kg), than other regions and earlier observation periods. Commodities mainly affected by ZON were corn (54% positive); wheat and wheat brain (47%), and finished feed (43%).
In 2004 165 samples were tested for T-2 toxin; the contamination rate was 40% with most of the positive samples originating from Northern Europe (64 positive of 152 tested).
In the year 2005, of 59 tested samples 32% were positive, again also primarily derived from the North (18 out of 32 samples). In 2006 only 46 samples were tested for T-2 toxin, all of them were negative. In contrary to earlier years only five of these samples were sourced in Northern Europe while the majority, i.e. 34 samples came from Central Europe, which also did not account for relevant T-2 contamination in prior years, so the result is not surprising at all.
Throughout the three year survey 109 samples were tested for Ochratoxin A, indicating an average contamination rate of 30%. In 2004 11 out of 42 samples tested positive, in 2005 15 out of 32, and in 2006 7 out of 35, respectively. No clear geographic allocation of contamination prevalence could be made, except in 2005, when the overall contamination rate was higher (47%), with samples from Central Europe and the South contributing primarily.
Out of 71 AfB1 analyses performed over the full project period, which included nine corn samples, 8 soy samples, one wheat and barley, each, as well as 18 finished feeds and 34 unspecified feed ingredients, only 5 samples were positive, the highest level identified at 14μg/kg in an unspecified feed ingredient.
Thus the aflatoxin sample population cannot be considered representative at all but is reported here in order to give a comprehensive picture of the full survey. Although scientific literature offers a broad variety of information on the effects of individual mycotoxins in various animal species, it is the multiple mycotoxin contamination that matters life-stock industry most, as it refers to the naturally occurring circumstances.
For example, aflatoxin and fumonisin B1, as well as DON or other trichothecenes (one or even more of them) and zearalenone frequently occur together in the same grain. Additionally, in the feed manufacturing process different batches of different raw materials are mixed together thus producing a totally new matrix with a new risk profile in the due course of manufacturing.
Poor livestock performance and/or disease symptoms observed in commercial operations may be due to the synergistic interactions between multiple mycotoxins. Strategies to prevent mycotoxicoses include pre- and post-harvest strategies; the latter are often categorized into physical, chemical and biological methods.
The best way would be the prevention of mycotoxins in the field in the first place, which is supported by proper crop rotation and fungicide administration at the right time. In case of toxin manifestation measures are required that act specifically against certain types and groups of toxins.
The most prevalent approach counteracting mycotoxins in the feed industry is to include sorbent materials, like clay minerals or yeasts, into the feed, for more or less selective removal of toxins by means of adsorption within the route of the gastrointestinal tract, or to add enzymes or microbes capable of detoxifying certain mycotoxins or toxin groups.
Authors: E.M. Bindera, E. Pichlerb, M. Kainzb, V. Starklc
a Biomin Research Center, Technopark 1, 3430 Tulln, Austria
b Quantas Analytik GmbH, Technopark 1, 3430 Tulln, Austria
c Biomin, 11 de Septiembre, No 2628, Piso 12, Dpto 4, Ciudad de Buenos Aires, ZIP 1428, Argentina
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3 de octubre de 2007
Great paper. More mycotoxin research data should be reported.
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