3 ways to cope with high-mycotoxin feeds
Mycotoxins are a group of secondary metabolites produced by fungal organisms. The main molds (and the mycotoxins they produce) are Aspergillus (aflatoxin, ochratoxin and neurotoxin), Fusarium (zearalenone, fumonisin, and the tricothecenes DON and T-2), and Penicillium (ochratoxin, citrinin and patulin). Toxic effects of mycotoxicosis in dairy cattle include reduced feed intake and performance, reproductive and digestive issues, immunosuppression, and death.
Environmental and physiological conditions both influence mycotoxin synthesis. Insect activity, humidity (high and low), and temperature are all environmental factors that influence mold growth and mycotoxin production. It is important to note that the presence or absence of visible mold does not guarantee the presence or absence of mycotoxins.
Mycotoxins are present in a wide range of livestock feeds. While the focus has been primarily on cereal grains, haylage and hay can also contain mycotoxins. Grain byproducts, such as distiller’s grains and corn gluten feed, can have mycotoxin concentrations two to three times greater than the parent material as little mycotoxin destruction occurs during processing and concentration occurs in the byproduct stream.
The most effective way to determine if mycotoxins are a problem is through appropriately conducted testing and careful animal observation. Testing for mycotoxins should be considered when symptoms of toxicity exist among a large population of animals on your farm and cannot be readily explained. For example, having a few animals in a group of 50 off feed with loose manure probably does not equate to a serious DON or T2 challenge.
Assuming you have determined that a mycotoxin challenge exists, here are three mitigation strategies:
1. Look for strategies to improve animal and rumen health.
Animals in a comfortable and low-stress environment are better able to deal with any feed-borne challenge. Likewise, a healthy rumen is the best first defense as the microbial population can degrade mycotoxins to varying degrees.
- Rot, mold or spoilage? Get rid of it.
- Sorting? Rectify it.
- Improperly mixed TMR? Check the mixer for wear and review mixing protocols.
2. Zero in on the challenged feed or feeds.
As stated earlier, corn-based feeds tend to be high-probability suspects, but any byproduct could be a mycotoxin source. When you’ve found the source, you have some options:
- Clean it. Using a grain screen with whole corn can knock mold and mycotoxins off the kernel, remove fines, and reduce mycotoxin load. Be sure to wear appropriate clothing (no skin exposed) and respiratory protection.
- Dilute it. If your stored corn is the problem, replace some with clean product. If corn silage is the problem, can you feed more haylage? If not, you may need to find a forage replacement.
- Change sources. Mycotoxin contamination of feedstuffs is often a regional issue. For example, ethanol plants often source local corn. You may find clean product outside of your geographical region.
- Divert to less-susceptible animals. This could end up refocusing the problem elsewhere, but, typically, pregnant heifers and mature steers are less susceptible to mycotoxicosis than high-producing, breeding dairy cattle.
3. Use a feed additive.
Research data shows some feed additives can directly or indirectly help mitigate the effects of mycotoxins. Some are based on the principles of adsorption, where the product interacts with the mycotoxin, prevents it from being absorbed and passes it through the digestive tract. These tend to be the most effective when aflatoxin is a concern. Researchers in Europe and the United Kingdom have evaluated microbiological solutions where the molecular structure of mycotoxins is altered, thereby “inactivating” it. Still, other options exist that do not address the mycotoxin directly, but protect and support the animal’s ability to metabolize and clear the mycotoxin from the body.
About the author: Dr. Eric Schwab grew up in a rural town in New Hampshire. He attended the University of New Hampshire – Durham, where he received bachelor’s degrees in dairy management and environmental and resource economics in 1998. While working in northeast Wisconsin, he met Dr. Randy Shaver and returned to academia at the University of Wisconsin-Madison to pursue his graduate degrees. In Shaver’s lab, Schwab’s master’s degree research focused on kernel processing and chop length in BMR corn silage. His Ph.D. dissertation focused on B vitamin nutrition and ruminal B vitamin synthesis in lactating dairy cows. In September 2005, Schwab joined Vita Plus on the dairy nutrition and technical services team. He lives in Deerfield, Wisconsin with his wife and their three sons.
Feed quality and nutrition
Forage storage and management