By Travis Meteer
Wet growing conditions in the Midwest have opened the door for several challenges in the 2015 wheat crop. As a result, farmers are seeing price docks and discounts at the elevator, mainly due to increased disease, low test weight, and sprout-damaged wheat. Depending on the dock and infection level this wheat may be best utilized as livestock feed, said a University of Illinois Extension beef educator.
"Farmers and ranchers will need to test grains and grain by-products before including them in animal diets," said Travis Meteer. "Storage of infected wheat is important. The grain will need to be dried down to less than 18 percent moisture to stop mycotoxin growth, and drying to 13 percent moisture is recommended for longer-term storage."
Mycotoxin levels, especially vomitoxin, should be tested. Feeding grains with elevated levels of vomitoxin can cause decreased feed intake, resulting in poor performance and compromised animal health in severe cases, Meteer explained. Several factors should be looked at when feeding wheat from this year's crop.
Low Test Weight
Low test weight does not always equal lower feed value. "Normally, low test weight grains have less starch and higher percentages of protein and fiber (seed coat). This can negatively impact feed value, but not always," Meteer said. "In most cases, if test weight is over 50 lbs. per bushel animal performance will not be negatively affected. If test weight is lower than 50 lbs. per bushel, the feed value is likely 90-95 percent the value of normal test weight."
Sprout-Damaged Wheat
Numerous research studies have looked at feeding sprout-damaged wheat. Meteer said the majority of research supports no difference in animal performance or feed efficiency. "However, sprout-damaged wheat is more susceptible to aflatoxin infection. If wheat is sprout-damaged, an aflatoxin test should be performed before feeding," he added.
Deoxynivalenol (DON) or Vomitoxin
Fusarium graminearum is the fungal disease that produces the mycotoxin DON. Often wheat that is infected will appear shriveled, pink in color, and is referred to as "tombstone" in shape, Meteer explained. Levels of vomitoxin are not reliably predicted visually. "Testing is the best method to determine the level of mycotoxin present," he added.
"Test and monitor vomitoxin (DON) levels in grains and grain by-products to be fed to livestock. Blending vomitoxin-bearing wheat with clean grains at the time of feeding can be a good practice to reduce vomitoxin levels in the diet," Meteer said.
While dilution is the solution, according to Meteer, he added that blending should only occur directly before feeding. "Blended grain is not legal for resale. Blending grains before feeding could result in contamination of clean grains," he said.
Toxin-binding agents can also be incorporated into a ration.
"Many studies have shown that phyllosilicate feed additives bind toxins (clays, sodium bentonite, aluminosilicate)," Meteer said. "These products can bind toxins and ensure they are not absorbed by the animal. It would be a good idea to use toxin binders in a ration that includes grains that are tested with elevated mycotoxin levels."
Feeding wheat will require management. Wheat will need to be processed to obtain good feed value. However, processing compounds rapidly fermentable properties, Meteer explained. "As a result, inclusion rates should be kept low in diets. Special attention will need to be given to ruminants that are transitioning from forage-based rations," he said.
Meteer recommends that producers look at the cost of wheat after processing and on and "in-the-bunk" basis. With moderate corn prices, farmers need to be cognizant of the real cost to using wheat as feed before purchasing or utilizing damaged wheat for feed, he said.
Straw from harvested fields that have tested high for a mycotoxin should be less risky than feeding the grain. "However, there can still be elevated levels of mycotoxins, including vomitoxin, in straw. Using the straw for bedding would be the lowest risk versus feeding straw in a ration. Straw that appears moldy and straw that is baled wet should be tested before feeding or bedding," Meteer said.
"Producers should be aware that mycotoxin-contaminated straw can be a problem but the risk is much less than feeding grains," he added.
The chart below illustrates the approved levels in livestock.
Intended Use | Grains and Grain By-products | Vomitoxin Level in Grains/ By-Products and Complete Diet* (ppm) |
Human Consumption | Finished wheat products | 1 ppm |
Swine | Grains not to exceed 20% of the diet | 5 ppm (1 ppm)* |
Chickens | Grain not to exceed 50% of the diet | 10 ppm (5 ppm)* |
Finishing (Feedlot) Cattle | Grain not to exceed 50% of the diet | 10 ppm (5 ppm)* |
Dairy Cattle | Grain not to exceed 50% of the diet | 10 ppm (5 ppm)* |
All other animals | Grain not to exceed 40% of the diet | 5 ppm (2 ppm)* |
Source: illinois.edu