Mycotoxins

Available Mycotoxin Data

Although between 300 and 400 mycotoxins are known, those mycotoxins of most concern, based on their toxicity and occurrence, are aflatoxin, deoxynivalenol (DON or vomitoxin), zearalenone, fumonisin, T-2 toxin, and T-2-like toxins (trichothecenes). In a recent survey of suspect feed samples, some amount of aflatoxin, deoxynivalenol, or fumonisin was found in over 70 percent of the samples tested. Over a 10-year period, data collected from suspect samples analyzed at the North Carolina State University (NCSU) Mycotoxin Laboratory show: that 20 parts per billion (ppb) or more aflatoxin occurred in 34 percent of corn samples tested; deoxynivalenol was detected in over 60 percent of poultry and dairy feeds tested; zearalenone was present in 15 to 20 percent of feedstuffs tested; and T-2 toxin was present in about 5 percent of the feeds tested. Fumonisin, a mycotoxin often associated with horse deaths, is thought to occur very frequently; however, its discovery is so recent that data on occurrence has not been established. Table 2 contains a summary of mycotoxin analyses obtained from suspect feeds, feed ingredients, and forages collected in North Carolina from 1989 through 1993. While the concentration of aflatoxin in suspect samples has remained fairly constant, the incidence of aflatoxin contamination has decreased. Nonetheless, both the incidence and concentration of aflatoxin can change as suddenly and dramatically as the weather. Thus aflatoxin monitoring should not be neglected. Furthermore, the effects of high levels of aflatoxin on animals are well documented, but exposure of animals to low levels of aflatoxin, especially when combined with other conditions or mycotoxins, can produce confusing symptoms, particularly in field situations.

Deoxynivalenol (DON), zearalenone, T-2 toxin, and fumonisin are all produced by molds of the genus Fusarium. Molds in this genus are found in virtually every lot of corn and collectively are capable of producing 70 different mycotoxins. Some strains of Fusarium may produce as many as 17 mycotoxins simultaneously. Thus Fusarium mycotoxins are the most frequently identified group of mycotoxins in grains and feeds.

Better control of mycotoxins will position producers for greater competitiveness and profitability. In addition, control of mycotoxins in animal diets would reduce the likelihood that mycotoxin residues would appear in animal products destined for human consumption.

Table 2. NCSU Mycotoxin Laboratory Analyses Obtained From
Suspect North Carolina Feeds, Feed Ingredients, and Forages
Collected From 1989 Through 1993.
                                                             

                                
                  Aflatoxin            DON           Fumonisin*
                 n    Av   %P      n    Av    %P      n    %P

MIXED FEEDS
1989-1993       342   116  11.4    572  1169  67.5    222  28.4
  1989           38    46  34.2     61  2727  62.3      0   -
  1990           40   358  22.5    107   802  73.8      0   -
  1991           46    34   8.7    116   511  62.1      0   -
  1992           77    24   2.6     94   643  48.9     85  23.5
  1993          141    48   7.8    194  1443  77.8    137  31.4

TMR              28    48  17.8     44  1379  61.4     12  25.0
Forages          56    57   8.9    177  1671  66.1     54  26.4
Concentrates    257   138  11.3    350   903  69.1    156  29.5
Corn Grain       52   346  17.3     63   599  63.5     33  60.6
Soybean Meal     11    30   9.1     14   220  57.1      6   0
Cottonseed       39   135   5.1     52  2679  46.2     26   3.8
Corn Silage      36    66  11.1    106  1847  75.5     33  39.4
Grass Hay         4     -   0       26  1110  42.3      9   0
Small Grain &
  Grass Silage   13     -   0       36  1568  61.1      9  11.1


                   T-2 Toxin        Zearalenone          
                n     Av   %P      n    Av    %P

MIXED FEEDS
1989-1993       430   364   4.2    538   397  18.0
  1989           41   151   7.3     62   552  27.4
  1990           47  2456   2.1     86   524  18.6
  1991           62     -   0      104   375   2.9
  1992           86     -   0       91   108   1.1
  1993          194   132   7.2    195   325  30.8

TMR              36     -   0       43   237  30.2
Forages         118   290   2.5    169   379  24.8
Concentrates    275   379   5.5    325   464  12.9
Corn Grain       58  1603   3.4     57   294   5.3
Soybean Meal     12    87  16.7     13   113  46.1
Cottonseed       41   274   4.9     50   292   6.0
Corn Silage      69    60   2.9     93   445  32.3
Grass Hay        19     -   0       29   114  13.8
Small Grain &
  Grass Silage   26   750   3.8     36   283  19.4


NOTE: 586 samples were tested. 2104 individual mycotoxin tests
were performed. 73.2% of samples were positive for at least one
mycotoxin. 61% of samples were positive for aflatoxin and one
other mycotoxin. 28.7% of samples were positive for all
individual mycotoxin tested.  

n   = Number of Assays.
Av  = Average concentration (ppb) in positive samples. 
%P  = Percentage (of samples) Positive. Note: Percentages
      are based on the following levels--Aflatoxin >20 ppb,
      DON >40 ppb, Fumonisin >5,000 ppb, T-2 Toxin >50 ppb,      
      Zearalenone >70 ppb.
TMR = Total Mixed Ration for ruminants includes the concentrates 
      and forages which make up the animals' total diet.

*Concentration was not determined on Fumonisin samples.

Prepared by

Mary Beth Genter, Extension Toxicology Specialist
Winston M. Hagler, Director of NCSU Mycotoxin Laboratory
Jeff A. Hansen, Extension Animal Science Specialist
Bob A. Mowrey, Extension Animal Science Specialist
Frank T. Jones, Editor, Extension Poultry Science Specialist
Matt H. Poore, Extension Animal Science Specialist
Lon W. Whitlow, Extension Animal Science Specialist http://www.ces.ncsu.edu/gaston/