Beware of Mycotoxins Even Without Visible Mold

In many cases, mycotoxins won’t alert livestock producers to their presence. There may be no visible mold and no bad smell.1 The infestation can be there — waiting to drag down production, decrease herd health, lower fertility and even be a food safety hazard.

“While mycotoxins are produced by specific molds, visible signs of mold may not translate to measurable mycotoxin levels and vice versa,” says Renato Schmidt, Ph.D., Technical Services – Silage, Lallemand Animal Nutrition. “It’s virtually impossible to completely avoid mycotoxin exposure. The toxins can be produced both on the growing crop and during storage and feedout.”

To help reduce mycotoxin production, producers can plant, insect and disease-resistant varieties, avoid leaving stubble standing in the field and practice crop rotation. In addition, it helps to avoid or minimize the effects of plant stressors like inadequate fertilization. Still, producers cannot avoid damage from pest infestation or weather events that can predispose crops to mold infestation and mycotoxin production.

When the crop has been stressed or physically damaged, the potential for mold infestation significantly increases. In these cases, Dr. Schmidt advises producers to take extra care with silage management.

To help minimize mycotoxin-producing molds — and all molds that cause spoilage — producers should use proven silage inoculants as part of a good overall management program. For example, silage inoculated with Lactobacillus buchneri  NCIMB 40788 will be more resistant to heating and spoilage as this organism reduces the growth of yeasts, the initiators of spoilage. In fact, forage inoculants containing L. buchneri  40788 have been uniquely reviewed by the FDA and allowed to claim improved aerobic stability.

In the ensiling structure, molds tend to grow in hot spots where there is air (oxygen) present, Dr. Schmidt notes. This is typically in poorly sealed surface layers, corners or shoulders of ensiled forages, or where pockets of air were trapped and packing was inadequate.

“If visibly moldy silage is identified, discard it,” Dr. Schmidt advises. “Feeding even small amounts of spoiled silage into a ration has been shown to reduce dry matter intake and NDF digestibility of the whole ration.2 While it may feel like an economic hit, you’re risking more in terms of lost production, herd health and reproduction if you choose to feed spoiled silage.”

1 Rankin M and Grau C. Agronomic Considerations for Molds and Mycotoxins in Corn Silage. University of Wisconsin-Extension. Focus on Forage,2002;(4)1. Accessed March 8, 2018. Available at

2 Whitlock LA, Wistuba T, Siefers MK, Pope RV, Brent BE, Bolsen KK. Effect of level of surface-spoiled silage on the nutritive value of corn silage-based rations. Cattlemen’s Day 2000. Accessed May 21, 2015. Available at:

Lallemand Animal Nutrition does not purport, in this guide or in any other publication, to specify minimum safety or legal standards or to address all of the compliance requirements, risks, or safety problems associated with working on or around farms. This guide is intended to serve only as a beginning point for information and should not be construed as containing all the necessary compliance, safety, or warning information, nor should it be construed as representing the policy of Lallemand Animal Nutrition. No warranty, guarantee, or representation is made by Lallemand Animal Nutrition as to the accuracy or sufficiency of the information and guidelines contained herein, and Lallemand Animal Nutrition assumes no liability or responsibility in connection therewith. It is the responsibility of the users of this guide to consult and comply with pertinent local, state, and federal laws, regulations, and safety standards.

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