By Matt Luebbe, UNL Beef Feedlot Specialist
Wet conditions this growing season have caused some wheat fields to produce scabby wheat that may not be suitable for milling or manufacturing. Scabby wheat is a result of Fusarium mold growth and this species of mold may produce deoxynivalenol (DON), a toxin commonly called vomitoxin. If high concentrations of scabby wheat are present it may be salvageable by feeding to cattle. Producers harvesting fields with scabby wheat should have the grain tested for DON to determine if it is present and what concentrations are in the grain. Not all scabby wheat will result in a positive test for DON but may be rejected based on quality of grain. Before feeding scabby wheat, DON should be tested to determine the level that is present in the grain.
Fusarium-damaged wheat kernels (left) and healthy kernels (right).
Higher levels of scabby wheat can be fed to cattle compared with other livestock because ruminal microbes can degrade or inactivate the toxin. Currently, the FDA recommends that DON concentration in beef cattle diets should not exceed 10 ppm. Previous research conducted at UNL evaluated feeding up to 10 ppm DON in finishing diets and there were no pathological or toxicological challenges observed. Furthermore, when replacing a portion of dry-rolled corn with wheat containing DON there was not a difference in average daily gain or feed efficiency.
Feedlot producers may be able to purchase scabby wheat at a discounted price and replace corn grain in the diet. When the concentration is known, diets can be formulated to ensure levels do not exceed the recommendation. Blending grains to reduce the concentration of DON is the most commonly used method to control risk. For more information about harvesting, storing and safe handling of infected wheat please refer to the Crop Watch website https://cropwatch.unl.edu/scabby-wheat-strategies.
The starch in wheat is more rapidly fermented than the starch in corn (Figure 1 http://go.unl.edu/vn9v). Because of these starch fermentation characteristics there is a greater potential for acidosis, bloat and founder. A general recommendation is to limit inclusion on a dry-matter basis to 50% of diet dry-matter unless producers are familiar with feeding wheat. Processing wheat by coarsely rolling or grinding greatly improves digestibility as long as fines are not produced. Adapting cattle slowly to wheat and including an ionophore will help reduce the challenges associated with acidosis.
Wheat grain has a similar energy value as corn and contains approximately 4-6 percentage units more protein. If acidosis can be managed, the feeding value of wheat (including both energy and protein) is 100-105% the value of corn. When comparing the cost of these two grains it is important to consider the dry-matter cost on a per-ton basis. Corn is traded at 84.5% dry-matter at 56 lbs/bu as-is. Wheat is traded at 88% dry-matter and 60 lbs/bu as-is. Because of these differences in moisture content and bushel weight, a producer can purchase 90% fewer bushels of wheat to equal the amount of corn on a dry-ton basis. Local markets and quality of grain will play a role in the decision to feed wheat.