Fungi are a fact of life on the farm, although their presence is often undetected or ignored. Unfortunately, fungal colonization of livestock feeds can be detrimental to animal health, mostly through the production of mycotoxins by some fungi. As the use of ethanol co-products increases in livestock feeding operations, it will be important to understand the nature and extent of any risks related to molds and mycotoxins.
There are essentially two ways that fungi can impact the safety of ethanol co-products as feed. Mycotoxins can be produced by some fungi that can infect corn grain. In Iowa, these are usually species of Fusarium that can produce fumonisins or deoxynivalenol (or other mycotoxins), or Aspergillus flavus, which produces aflatoxins. When grain is processed into ethanol, these mycotoxins are not destroyed, but become concentrated in the co-products.
When co-products are delivered to the farm, they can become colonized by fungi in the environment. This may cause problems with nutritive value or palatability, but some of these fungi also may be mycotoxin producers. There has not been much information available about the types of fungi that prefer to colonize in these materials, so the likelihood of mycotoxin contamination by this route is unclear. As one would expect, wet or modified distillers’ grains are more likely to be quickly colonized by fungi than are dried distillers’ grains.
In order to learn more about fungal colonization of coproducts on the farm and the potential for mycotoxin contamination, sampling studies were conducted at the ISU Beef Nutrition Farm and the McNay Research/Demonstration Farm. At one or both locations from September through March, periodic samples were taken of wet distillers’ grains (WDGS), modified distillers’ grains (MDGS), dried distillers’ grain (DDGS), condensed distillers’ solubles (CCDS), and a hay/CCDS mixture. We tested these in laboratory for the presence of fungi,
especially those that can produce mycotoxins. No attempt was made to quantify changes in the level of molds over time. The objective was to identify the major types of fungi present, and determine if any were mycotoxin producers. A few samples were checked for mycotoxins at the ISU Veterinary Diagnostic Laboratory.
Source: Dr. Gary Munkvold, Department of Plant Pathology