Every harvest season carries with it the dangers of mycotoxin – toxic substances produced by molds growing on crops, either before harvest or in storage.
According to Bill Seglar, Nutritional Sciences Manager for Pioneer, only a handful of mold species produce mycotoxins, out of the thousands that grow in stored grain and feed. But when they are present in dairy feed, mycotoxins can be detrimental and even deadly.
Identifying Mycotoxins in Cattle Symptoms and Health Issues
In a University of Wisconsin Dairy Extension publication, Seglar said symptoms of mycotoxin contamination are rather vague, and may include reduced feed intake, feed refusals, unthriftiness, rough hair coat, reduced milk production, poor body condition and reproductive problems. He added field investigations also have tagged mycotoxins to fresh-cow problems, including displaced abomasum, ketosis, retained placenta, metritis, mastitis, and fatty livers.
The Impact on Calves and Heifers
Unfortunately, mycotoxins don’t just unleash their subtle-but-serious wrath on lactating cows. Ellan Dufour, Dairy Research Nutritionist with Hubbard Feeds, was curious about the specific effects of mycotoxin contamination on young stock, noting that most mycotoxin research in dairy animals had been focused on the impacts on lactating cows.
“If mycotoxins can have such an extreme influence on cow health and production, then we can assume they also can impact the growth, performance, and health of calves and heifers,” she said.
Dufour and her colleagues partnered with researchers at the University of Minnesota-Waseca to evaluate the effects of mycotoxin-contaminated starter grains on the health and development of preweaned calves and older heifers.
Quantitative Effects on Young Stock Performance
Not surprisingly, they found a wide array of symptoms and setbacks, ranging from reduced rumen function and feed efficiency, to delayed sexual maturity and suppressed immunity. Specifically, they identified the following, quantitative effects of mycotoxins on performance and health of calves through 56 days of age:
- 10% reduction in average daily gain
- 15% reduction in calf starter intake
- 10% reduction in dry matter intake
- 50% increase in treatment costs
Immunosuppression and Vaccine Failure
Of additional concern in calves is the immunosuppressive effects of mycotoxins during a critical life stage. University of Kentucky veterinary researchers Michelle Arnold and Cynthia Gaskill noted that aflatoxin, a highly potent mycotoxin, may result in vaccine failure and/or poor response to antibiotics.
The Kentucky researchers cited a field case in which young calves (300-450 pounds) were fed a ration of corn, whole cottonseed, cotton gin trash, molasses, and mineral for several months. The feedstuffs were evaluated for mycotoxins when the calves started to exhibit signs of depression; lethargy; loss of body movement control, poor weight gain; respiratory disease with poor treatment response; and death.
