By Jean English
If the grain or feed that you buy for your animals is green or blue/green and stinky, it’s not good. That was the bottom line of LeBelle Hicks’ talk at the Maine Agricultural Trades Show in Augusta in January – and it was what people in the audience, who had inadvertently purchased moldy grain more than once, wanted to know.
Hicks, who is the toxicologist on the Maine Board of Pesticides Control staff, gave a superbly organized and clear presentation on Fusarium mycotoxins and livestock. Fusarium is just one of 14 genera of fungi known to produce mycotoxins. Mycotoxins are, she explained, chemical by-products of fungi, and they can affect horses, sheep, cattle, poultry and pigs. They are a global problem, with 25% of the world’s food crops affected. Poverty increases the chance that people will use moldy grains, since they may have no other food or feed choices.
When grains are found to be contaminated, they may be rerouted from products for human consumption to animal feed. Blending with uncontaminated feed can bring concentrations to an “acceptable” level.
Fusarium may grow on grains and forage crops when they are in the field (as in Fusarium head blight in wheat and in corn ear rot), or they may grow during storage. The fungi may produce tricothecenes, which can stop animals from making proteins; alter chemicals in the brain; or affect the immune system. Symptoms in livestock could include intestinal tract bleeding and tissue death; vomiting and feed refusal, with a decrease in weight gain; or interference with reproduction. Zearalenone, another mycotoxin produced by Fusarium, mimics the female hormone estrogen and can cause infertility, increase growth in uterine and breast tissue, decrease sperm, and increase the incidence of still births. Fumonisins produced by Fusarium in corn can change fat usage and alter the functioning of brain, lung and other tissues.
The occurrence of these mycotoxins in grains is not uncommon. Hicks showed data from Canada showing that 33% of the wheat sampled, 43% of the wheat foods, 86% of corn and 18% of barley and malt tested positive for one trocothecene (DON). Concentrations ranged from 7 to 10,500 parts per billion, and the lowest acceptable level of DON is 300 ppb. Similar data were shown for other mycotoxins, and Hicks noted that multiple fungal infections and multiple mycotoxins can occur at the same time. Further confusing research in this area, toxicogenic fungi may be present but not indicate a problem; while, on the other hand, fungi may not be present but mycotoxins are (if, for instance, a fungus grew on a grain for a period while it was in the field, then weather conditions changed so that the fungal growth ceased; if mycotoxins were produced before the fungus stopped growing, they could still exist in the grain at harvest).
Hicks suggested that producers who are having problems with livestock should consider mycotoxins as a possible cause; and that producers should try to provide growing and storage conditions that do not favor fungal growth. Fusarium grows under conditions of high relative humidity; water and temperature stress; insect damage; high crop and weed densities; and in susceptible cultivars.
Hicks recommended the North Carolina State University Cooperative Extension publication from 1994, “Understanding and Coping with Effects of Mycotoxins in Livestock Feed and Forage,” electronic publication DRO-29 available at www.ces.ncsu.edu/disaster/drought/old/dro-29.html. She also provided the following websites:
Fusarium – Head Blight in wheat:
Fusarium graminearum – Ear Rot in corn:
F. moniliforme – Ear Rot in corn
Aspergillus in corn
Aspergillus in peanuts
Claviceps (Ergot) on rye
Maine Dept. of Food and Agriculture website: www.state.me.us/agriculture
Plant Pathology: Grace O’Keefe, 287-3891; grace.o’[email protected]
Feed Inspection Program: Hal Prince, 287-3841; [email protected]
Veterinary Services – 287-3701
Donald Hoenig – [email protected]
Chip Ridky – [email protected] me.us
Steve Ellis – [email protected] gove
Toxicology information – 287-2731
Lebelle Hicks – [email protected]
Univ. of Maine Cooperative Extension Service: https://extension.umaine.edu/
Pest Management Office – 800-287-0279
Animal health issues – 800-287-7170