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Mold Interpretation

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Conditions Favoring Mold Production:

Molds grow over a temperature range of 50-104°F and a pH range of 4-8. Mold spores are in the soil and in plant debris ready to infect the growing plant in the field or during storage.

Mycotoxin Production:

Some molds produce mycotoxins under certain conditions, but the presence or absence of mold does not directly indicate the presence or absence of mycotoxins. For example, Fusarium molds have been reported to grow prolifically at 25-30°C without producing much mycotoxin, but at near freezing temperatures they produce large quantities of mycotoxins with minimal mold growth (Joffe, 1986). Molds can be detrimental to animal performance regardless of mycotoxin contamination.

Mold Identification:

Mold identification can be used to determine which mycotoxins are likely to be present. See the chart below for information on molds and their associated mycotoxins.

Mold Species - Producing Toxin Color Toxin Conditions favoring production
Aspergillus Yellow-Green Aflatoxin Ochratoxin Heat and drought stress pre-harvest Heat and humidity postharvest
Fusarium White to Pinkish-White

T-2 Toxin Vomitoxin(DON) Fumonisin

Grows both pre and postharvest. Excessive moisture during flowering and grain fill of wheat. Cool wet growing season with insect damage. Dry conditions mid-season followed by wet weather. Associated with ear and stalk rot in corn, head scab in small grains, red ear rot, and pink ear rot
Penicillium Green to Green-Blue Ochratoxin

Cool, wet, and low pH (acid tolerant) postharvest

Cladosporium Dark blue-green to gray or black None

Early frost, neutral pH, high grain moisture (30-40%), temperatures at 75-125ºF


cfu/gram Feeding Risk and Cautions
Under 500,000 Relatively low count
500,000 to 1 million Relatively safe
1 to 2 million Discount energy (x .95) Feed with caution
2 to 3 million Closely observe animals and performance Discount energy (x .95)
3 to 5 million Dilute with other feeds. Discount the energy (x .95) Observe closely
Over 5 million Discontinue Feeding

a Risks refer primarily to effects of mold per se without regard to possible mycotoxin content. Depressed digestibility, feed intakes, and performance may occur from a high mold content without mycotoxins present. Harmful mycotoxins may be present, even when there is little or no obvious mold content.

b Mold spore counts sometimes may underestimate the degree of mold present, especially in feeds that have been ensiled for some weeks. Observe and record relative amounts of mold present.


Joffe, A.Z. 1986. "Fusarium Species: Their Biology and Toxicology". John Wiley and Sons, Inc. New York.

Kurtzman, C.P., B.W. Horn, and C.W. Hesseltine. 1987. Aspergillus nomius, a new aflatoxin-producing species related to Aspergillus flavus and Aspergillus tamarii. Anton v. Leeuwenhoek 53:147-158.

Adams, Richard S., Kenneth B. Kephart, Virginia A. Ishler, Lawrence J. Hutchinson, and Gregory W. Roth. "Mold and Mycotoxin Problems in Livestock Feeding." Dairy Cattle Nutrition (Penn State Extension). Penn State Extension, n.d. Web. 17 Sept. 2013.

Hoffman, P., R. Shaver, and P. Esker. 2009. High moisture corn, aerobic stability, feed additives, and mycotoxins: Common questions. The 2009 Wisconsin Corn Corp.

Wright, C., B. Holland, R. Daly and L. Osborne. 2009. Moldy corn for beef cattle. SDSU Extension Extra: 2069.

For more information call Dairyland Laboratories, Inc. at 608-323-2123 or contact us here.