The recent corn harvest was quite unfavorable, and livestock feeders need a long-term plan for feeding the 2009 crop. In much of the Midwest, corn harvest was later than in any year in recent memory, and the prolonged moist conditions in many cases caused molds to develop on the kernels, as ears were standing on stalks in the field.
These ear rots have resulted in many questions concerning possible mycotoxin production when conditions are cool and wet. “Wet conditions are ideal for mold growth,” says Randy Cragoe, a ruminant nutrition specialist with Cragoe Consulting at Brookings, S.D.
• Think beyond harvest before feeding corn from this fall.
• Test corn that had mold on ears in the field for mycotoxins.
• Problems vary for livestock fed corn contaminated with mold.
“Ideally, grain at harvest shouldn’t have more than 13% to 14% moisture,” he adds. “If the grain contains more than this recommended moisture, it is highly suggested to use mold inhibitors, which are organic acids, at appropriate concentrations. These mold inhibitors reduce the further growth of molds and the subsequent mycotoxin production.”
Cragoe says high-moisture corn should be analyzed for harmful mycotoxins before storage or feeding, and should be stored in separate, temporary structures such as bags to avoid contamination of clean corn in storage bins. Also, care should be taken to make sure silos and bunks are packed well. The use of silage inoculants can be valuable. Care should be taken to store straw and hay properly as they also can be a source of mycotoxins.
The toxins can be produced by molds found in soil and can grow on grain, forages and silage. Mycotoxins can form in the field preharvest and may continue to form under suboptimal storage conditions postharvest. Aflatoxins and Fusarium mycotoxins often are associated with moldy corn.
Problems for livestock can be quite variable depending on species and type of toxins identified in the feed source, says Cragoe. Swine and horses have a high sensitivity to contaminated feed, and feed avoidance by the animal is a common symptom of mycotoxin issues.
For gestating and lactating sows, if they do eat the feed, symptoms such as immune suppression, reduced ability to absorb nutrients from the gastrointestinal tract and a reduced use of proteins in the body are more common.
Ruminant animals are the most resistant due to microorganisms in the rumen that can degrade toxins before they enter the bloodstream. Harmful effects can be observed, however, in high-producing dairy cows. Reduced milk production, impaired reproduction and immunity suppression in cows are possible effects of mycotoxins.
Use a feed additive?
Once mycotoxins have made their way into the feed, there are still a few options available to the farmer. “You either should not feed the contaminated feed or you should use an effective mycotoxin adsorbent,” says Cragoe.
There are two types of adsorbents: silica-based polymers and carbon-based organic polymers. Silica-type materials are readily available, and many are effective against aflatoxins but ineffective against other types. An organic glucomannan polymer extracted from the cell wall of yeast is a natural fiber source and often can be used at practical levels of inclusion.
Need more information? Cragoe says mycotoxins are a leading area of study at Alltech. Visit www.alltech.com.
Source: Cragoe, Alltech
This article published in the February, 2010 edition of WISCONSIN AGRICULTURIST.
All rights reserved. Copyright Farm Progress Cos. 2010.