Vomitoxin – Important For Many Livestock Producers To Understand

DR. TERESA L. STECKLER

SIMPSON, ILL.
   As if the weather hasn’t thrown us enough curve balls this year, there is another potential concern for people raising livestock – vomitoxin. Several reports suggest that 2016 corn being sold has vomitoxin. The problem is stemming from heavy rain before and during the 2016 harvest and then storing wet grain.
   Vomitoxin is also known as deoxynivalenol (DON).  The occurrence of deoxynivalenol is associated primarily with Fusarium graminearum (Gibberella zeae) and F. culmorum, both of which are important plant pathogens which cause fusarium head blight in wheat and gibberella or fusarium ear blight in corn.
   Vomitoxin belongs to a class of mycotoxins (trichothecenes) which are strong inhibitors of protein synthesis; exposure to vomitoxin causes the brain to increase its uptake of the amino acid tryptophan and, in turn, its synthesis of serotonin. Increased levels of serotonin are believed to be responsible for the anorexic effects of DON and other trichothecenes.
   Any why is this important to know, you might say. Turning corn into ethanol creates a byproduct called distillers dried grains (DDGs).  Thus, if you feed distillers dried grains (or just straight corn to your livestock), it may impact you. The refining process triples the concentration of mycotoxins, making the feed byproduct much less attractive as an animal feedstuff due to the potential health risks.
   Vomitoxin usually causes pigs to vomit following consumption of feed with high concentrations of the toxin. Swine are the most sensitive livestock species to vomitoxin. The most common effect of vomitoxin is reduced feed intake or feed refusal. Diets containing 5 ppm can reduce feed intake by 30 to 50 percent. Vomiting has been reported in swine ingesting finishing diets containing greater than 10 ppm vomitoxin. The lowered weight gain associated with the toxin is due directly to the reduction in feed intake.
   Numerous studies have been conducted in broilers and layers with vomitoxin-contaminated grains. Adverse production effects were not observed in broilers and layers ingesting feed contaminated with up to 5 ppm in the diet for 168 days. Effects on a hen’s egg production, egg weight, feed efficiency, fertility, or chick weights at hatching were not detected in layers ingesting feed containing 18 ppm vomitoxin in the diet. Also, reports have indicated that no ill effects were detected in turkey poults given a diet containing 5 ppm of vomitoxin.
   Ruminants appear to be less sensitive to dietary vomitoxin concentrations than are monogastrics (particularly swine). This may be due to the presence of microorganisms in the rumen. It is postulated that these microorganisms partially degrade the toxin prior to absorption into the blood stream and vital organs of the animal.
   In trials with dairy cattle, up to 6.5 ppm vomitoxin has been fed to dry cows and 12 ppm to lactating cows in the concentrate dry matter for 42 and 70 days, respectively, with no effect on milk production, body weights, or milk composition. Experiments with cattle and sheep also indicate that the effect of vomitoxin on animal health or performance is negligible. Diets containing vomitoxin, but negative for other prevalent toxins, indicate that up to 15 or 10 ppm vomitoxin in the diet dry matter were tolerated by sheep and cattle, respectively, without any adverse effects on animal health or performance.
   According to the Food & Drug Administration, advisory levels for livestock consumption of DON are as follows:
   • 5 ppm of DON on grains and grain byproducts destined for swine, with a recommendation that these ingredients not exceed 20 percent of their diet.
  • 10 ppm of DON on grains and grain byproducts intended for chickens, with a recommendation that these ingredients not exceed 50 percent of the diet.
   • 10 ppm of DON on grains and grain byproducts (on an 88 percent dry matter basis) destined for ruminating beef and feedlot cattle older than four months, and 5 ppm DON for ruminating dairy cattle older than four months.
   • 5 ppm of DON on grains and grain byproducts destined for all other animals, with the added recommendation that these ingredients not exceed 40 percent of the diet.
   Thus far reports for vomitoxin-contaminated grains are concentrated in Indiana, Wisconsin, Ohio, and parts of Iowa and Michigan. In Indiana, 40 of 92 counties had at least one load of corn harvested last fall that has tested positive for vomitoxin, according to the Office of Indiana State Chemist’s county survey versus no more than four counties in 2014 and 2015.
   Although the reports are coming from up north, just be aware of the potential issues that can arise from feeding DONS infected feedstuffs. Also depending on the livestock on your farm, be sure to know the maximum tolerated levels for them. Good luck! ∆
   DR. TERESA L. STECKLER: Extension Specialist, Animal Systems/Beef, Dixon Springs Agricultural Center, University of Illinois