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Pennsylvania has experienced unprecedented rainfall amounts throughout the summer. Molds and mycotoxins thrive when the temperature and moisture levels are ideal, and their formation can start in the field. The best plan is to minimize their growth in storage by making sure best management practices are in place for harvest, storage, and feed out. Silage or feed additives cannot be the only means for managing mycotoxins in the forages and ration.
Dealing with uncooperative weather patterns can increase the occurrence of molds and mycotoxins. Cool, wet growing seasons may delay corn maturity. The strategy to delay harvest so corn can mature and dry down or to avoid muddy field conditions can end up promoting mold growth. The challenge is finding that right time point so that the forage or grain is not compromised to the point of creating several months of production and health issues for the cows. Harvesting good quality corn for silage or grain still depends on the proper moisture content and particle size for the storage structure. A silage additive cannot overcome extremes in ensiling practices that result in air infiltration, which will advance the development of mycotoxins.
There are over 400 mycotoxins that occur naturally and only a few have been studied extensively. So even if a forage or grain is suspect and the test results show below concern level amounts, mycotoxins should not be ruled out as a culprit. It is also true that lapses in feeding management or nutrition can result in similar symptoms as mycotoxins. This makes it extremely difficult to say with 100 percent accuracy that mycotoxins are or are not the problem. The old saying that “dilution is the solution” sometimes is the best approach when all other strategies have met with less than stellar results.
It is possible that feeds in a certain portion of a bin or silo are the culprit for mycotoxins. Sometimes discontinuing the use of a silage or high-moisture grain and re-sealing the silo for several weeks may stop further formation of mold or mycotoxins. Thus, the feed may be used later to some extent after discarding the next 6 to 10 inches of material and any obviously moldy or spoiled feed.
Animals most susceptible to mycotoxins are young calves, pre and post fresh, or early lactation cows. Therefore, if contaminated feed must be used, feed it to older replacement cattle and dairy cows in late lactation. The mycotoxins of most concern are zearalenone, dexoxynivalenol (DON) or vomitoxin, diacetoxyscipernol (DAS), T-2, HT-2, and ochratoxin. Zearalenone is associated with impaired reproductive performance, and levels of 4 to 7 ppm in the total ration dry matter would be a concern. However, reproduction is a very dynamic process for the cow and this alone should not be the only focus when examining the cause of poor pregnancy rates. The other mycotoxins can depress dry matter intake resulting in ketosis, displaced abomasum, reduced milk production, and sometimes diarrhea. The T-2 and HT-2 toxins have been associated with hemorrhaging. For every problem listed regarding performance and health there are many other management or disease issues that could cause the same symptoms.
Weather conditions in 2018 have been ripe for potential mold and mycotoxins problems. Keep them on the radar, but do not automatically assume they are the sole reason for poor animal performance. Follow good management practices from the field to the farm to help minimize their impact on feed quality and health.
Action plan for dealing with mycotoxin problems.
Goal – Implement best management practices at harvest, storage, and feed out to minimize potential effects of molds and mycotoxins.
- Step 1: Ensile corn silage and grain at the proper moisture content and particle size for the storage structure.
- Step 2: If mold is obvious in the field and/or conditions are right for mycotoxin development, utilize a suitable silage or grain additive. Consult with the appropriate consultant for the best product based on solid research and proven capabilities.
- Step 3: If silage and/or grain is suspected of being contaminated, utilize the “quick test” approach from a lab (qualitative analysis). If animal performance is already being compromised, consider the more expensive confirmatory tests (quantitative).
- Step 4: Evaluate all aspects of feeding management and nutrition to confirm they are not the culprit for poor animal performance.
- Step 5: Consider feed additives along with diluting the contaminated feed in the ration. Monitor animal performance and make adjustments as needed based on how well animals return to normal.
Monitoring must include an economic component to determine if a management strategy is working or not. For the lactating cows income over feed costs is a good way to check that feed costs are in line for the level of milk production. Starting with July 2014’s milk price, income over feed costs was calculated using average intake and production for the last six years from the Penn State dairy herd. The ration contained 63% forage consisting of corn silage, haylage, and hay. The concentrate portion included corn grain, candy meal, sugar, canola meal, roasted soybeans, Optigen® and a mineral vitamin mix. All market prices were used.
Also included are the feed costs for dry cows, springing heifers, pregnant heifers and growing heifers. The rations reflect what has been fed to these animal groups at the Penn State dairy herd. All market prices were used.
Income over feed cost using standardized rations and production data from the Penn State dairy herd.
Note: Penn State's August milk price: $16.56/cwt; feed cost/cow: $5.22; average milk production: 79.0 lbs.
Feed cost/non-lactating animal/day.