More on Mycotoxins
What are mycotoxins?
Mycotoxins are metabolic by-products or waste products produced in the later part of the life cycle of a spore. They may remain in feedstuffs long after the fungus that produced them has died. Therefore, toxins can be present at potentially dangerous levels in feedstuffs that are not visibly moldy.

Although this corn appears to be high quality (with no visible signs of mycotoxins), testing indicated high levels of toxin producing molds present.     


Back lighting shows that the top row is good quality grain (the germ portion of the kernel naturally appears dark). But in the bottom row, the dark areas in the middle portion of the kernel indicate they have been invaded, damaged by mold spores, & depleted much of their energy content.

How many different mycotoxins exist?
While there are over 300 identified mycotoxins, the three most widespread affecting cattle are aflatoxin, vomitoxin and zearalenone. Both vomitoxin and zearalenone (produced from the mold fusarium) are of concern in cool climates while aflatoxin is always a concern in the southern states and when temperatures rise in the hot/dry summer of cooler climates.

How do they affect cattle?
Mycotoxins can be poisonous, mutagenic, teratogenic or carcinogenic when consumed. In general, they can increase disease incidences and reduce production efficiency in cattle through:
  1. Alteration in nutrient content, absorption and metabolism
  2. Changes in the endocrine and neuroendocrine function
  3. Suppression of the immune system
Typical symptoms of all three of the common mycotoxins include reduced feed intake and milk production as well as decreased reproductive performance. Let's look at some of the effects of these individual mycotoxins:

Aflatoxin
  • Liver damage and liver tumors
  • Hemorrhage: intestinal tract & kidneys
  • Decreased cellulose digestion in rumen
  • Embryonic death and birth defects
Vomitoxin (Deoxynivalenol-DON)
  • Digestive disorders (diarrhea)
  • Hemorrhage: stomach, intestines, bladder, kidney
  • Edema
  • Oral lesions
  • Dermatitis
  • Blood disorder
  • Elevated somatic cell counts
Zearalenone
  • Mimics the effects of estrogen
  • Interferes with:
        Ovulation and implantation
        Conception
        Fetal development–abortions
        Viability of newborn animal
  • Vaginitis–vaginal secretions
  • Mammary gland enlargement in virgin heifers
In many instances, herd owners don't even realize they have a mycotoxin problem but are suffering great economic losses. Barney Harris, Jr., Ph.D., PAS, states, "Mycotoxin contaminated feeds depress livestock and poultry performance causing U.S. producers millions of dollars in losses. Often these economic losses are due to subtle, nonspecific effects on animal performance."Young animals are very susceptible to the effects of mycotoxins and should not be overlooked.

Why is it becoming more of a concern?
The potential for mycotoxins negatively affecting cows increases as:
  • No-till and low-till agronomy is becoming more commonplace. Crop residues are no longer plowed under and these residues left on the surface make for an ideal mold-growing environment. Then, new crops planted often absorb the mod spores
  • Reduced crop rotation also adds to the residual mold problem.
  • Expanded operations store large quantities of high moisture feedstuffs in ways that introduce oxygen and, therefore, provide excellent mold-growing conditions.
  • The primary use of anhydrous, a soil sterilant, as a nitrogen source.

Ideal mold growing conditions.

 

 

What levels of mycotoxins can cause problems?
Research at the NCSU has shown that even low levels of mycotoxins can decrease milk production and increase days open. For instance, .2 ppm vomitoxin levels equate to 1 lb. in milk production loss while .8 PPM decreased milk production by 5 lbs. and days open increased by 8. Dr. John Doerr, Ph.D., University of Maryland, emphasizes, "When there is a combination of toxins, the simultaneous occurrence can profoundly affect the toxicity and the results can be devastating. The symptoms exhibited may not be what you'd normally expect."

Which product is best for my herd?
We recommend having your feedstuffs tested for aflatoxin, vomitoxin (DON), and zearalenone. The results will indicate which product will help you the most and then, we can embark on a program that will produce results without wasting time in a guessing game. Proper sampling requires drawing several TMR samples or suspect feeds and mixing them together thoroughly.