Feeds vomitoxin

Contamination occurs primarily in wheat, barley, rye, and maize. Type A trichothecenes include mainly T-2 toxin, HT-2, and diacetoxyscirpenol (DAS) mycotoxins of the group B include mainly 4-deoxynivalenol (DON), commonly known as vomitoxin, and nivalenol (NIV). Toxic effects include nausea, vomiting, visual disorder, vertigo, throat irritation, and feed refusal in farm animals. The most toxic is T-2, followed by DAS and NIV, with DON being the least toxic in acute toxicity studies but the most widespread in grains worldwide and therefore the most studied. Issues related to chemical and physical data, occurrence, toxicity, absorption, distribution, and metabolism of trichothecenes are reviewed in WHO (89) and IARC (34). Physicochemical data for some selected Fusarium toxins is given by Sydenham et al. (90). The molecular structures of the main trichothecenes are shown in Fig. 9. 

Irish research (Lawlor and Lynch, 2001) has shown that cereals grown there may be contaminated with vomitoxin, zearalenone, fusaric acid or ochratoxin. The presence of aflatoxins in animal feeds in Ireland is considered likely to be due to the importation of feed ingredients from warmer climates. 

Other mycotoxins, including DAS, DON, and ochratoxin, are not of major economic importance although they can be toxic to food-producing animals. DAS causes necrosis and erosion of the oral mucous membranes. Consequently, affected animals exhibit feed refusal and have impaired growth. DON (also called vomitoxin ) induces vomiting and feed... 

In the U.S., routine analysis of grains for vomitoxin didn t begin until 1981, about a year after the Canadians first surveys. In 1981, the U.S. cornbelt was heavily contaminated with vomitoxin from Iowa to New York. In Illinois, 274 of 342 samples of grain (mostly corn, but some wheat and oats) and animal feeds were found to contain from 0.1 to 22 ppm with a mean of 3 ppm vomitoxin ( ) In 1982, the winter wheat crop of Kansas, Nebraska, Missouri and Iowa was contaminated with vomitoxin. A million acres of land in southeast and southcentral Nebraska (one third of the Nebraska wheat producing area) contained scabby wheat, a condition caused by the Fusarium mold that produces vomitoxin. A survey of 87 samples of wheat heads, grain, chaff, and straw found 76 (87%) to contain over 0.3 ppm, 63 (72%) over 1 ppm and 11 (13%) over 5 ppm vomitoxin (4). The scabby wheat area extended into north-... 

Poultry have been found to be highly resistant to the effects of vomitoxin. A diet containing sufficient naturally contaminated corn to provide a 50 ppm vomitoxin concentration was fed to 6 day old broiler cockerels for 6 days with no effect on growth or feed consumption. The only observed effects of the contaminated diet were plaques in the mouth and gizzard erosion (19). When a diet containing 15 ppm pure vomitoxin was fed to broilers for 6 weeks, no deleterious effects were noticed (20). 

In both of these cattle studies, naturally contaminated wheat was the source of vomitoxin in the feed. 

When the results of subchronic and chronic studies on the reproductive, immunosuppressive, and other possible adverse effects of vomitoxin have been completed, it will be easier to judge how much of a hazard vomitoxin poses for the feed and the food industries. 

FIGUItE 29-4. Correlation between feed refusal and doxynivalenol (vomitoxin, DON) content of the feed in swine. 

Deoxynivalenol, also known as DON or vomitoxin, is a trichothecene mycotoxin that affects brain neurochemistry (e.g., dopamine and 5-hydroxyindolacetic acid), leading to nausea and appetite suppression. Feed refusal or decreased feed intake occurs through a learned response known as "taste aversion."... 

Protein levels were only slightly lowered by the heating process but bound protein was increased. Feeding studies are underway to determine the feed efficiency of the roasted commodities. Similar results for vomitoxin are reported by Young et al. in Canada. 

Vomitoxin is a deoxynivalenol derivative. The toxin causes feed refusal, vomiting, and lower feed efficiency. The brewing industry is especially concerned about these toxins because they may contaminate beer when infested barley or malt is used. 

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