Drought conditions have reduced forage supplies and increased hay prices, causing many cattle producers to look for alternative winter feed resources. Corn residue can help stretch limited hay supplies. However, baled corn residue is not equivalent to grazed corn residue or to a bale of grass hay. Additionally, how the residue is harvested and fed can have a major impact on its feeding value. 

Grazing and baling corn residue are not the same 

Corn residue is made up of stalk, leaf, husk, and cob, and these plant parts differ considerably in feeding value. Husk is highly digestible, leaf is intermediate, while cob and stalk are the least digestible. When cattle graze corn residue, they selectively consume the highest-quality portions of the plant. Cattle typically select any remaining grain first, followed by husk and leaf, while consuming relatively little cob and stalk. As a result, the diet cattle select while grazing can be considerably higher in quality than the average nutrient composition of all the residue standing in the field. This ability to select is one reason grazing is generally the best way to use corn residue to meet the nutrient needs of cows. Baling changes the situation. Raking and baling collects more of the low-quality stalk that cattle would normally leave behind when grazing. When whole bales are fed, cows can still sort through the residue and select more of the husk and leaf, but that selection results in considerable refusal and waste. Grinding changes the feed even more. Once corn residue is ground and incorporated into a ration, cattle can no longer sort out the stalk. At that point, they are consuming the entire material harvested, making the proportion of stalk in the bale much more important. 

Harvest method matters 

Because corn plant parts differ so much in feeding value, harvest methods that collect more husk and leaf while leaving more of the lower stalk in the field can improve the quality of the resulting feed. The traditional method of harvesting corn residue is to rake the field after grain harvest and bale the windrow. This collects a large amount of residue, but it also incorporates considerable stalk into the bale. Another option is to disengage the rear spreader on the combine and allow the material exiting the combine to fall directly into a windrow that can be baled without raking. This system is sometimes referred to as the EZBale method. Because less stalk is incorporated, the resulting feed is more digestible than conventionally raked and baled residue. In our research, conventionally baled corn residue was estimated to contain about 39% TDN compared with about 44% TDN for EZBale residue. 

The EZBale system also removed considerably less material from the field. In our research, conventional raking and baling removed an estimated 77% of the available residue compared with approximately 34% when combine tailings were windrowed and baled. Actual removal will vary with grain yield, equipment, and field conditions, but the difference illustrates an important principle: harvesting less residue can produce a better-quality bale while leaving more material on the soil. This may be particularly important on drought-stressed, low-yielding dryland fields where relatively little residue is present to begin with. Higher-yielding or irrigated fields and fields with lower erosion risk may be better candidates for residue harvest. 

Timing of baling can also affect what ends up in the bale. Husk is one of the most digestible components of corn residue, but it is also light and can be moved or lost from the field by wind. As time passes after grain harvest, loss of husk can reduce both the amount and quality of residue available for harvest. If corn residue is going to be baled for feed, harvesting sooner rather than later can help capture more of these higher-quality plant parts.  

What is the feed value of a corn residue bale? 

Corn residue bales can vary substantially in feeding value because stalk, leaf, husk, and cob differ greatly in digestibility, and the proportion of each captured in the bale depends on harvest method and timing. Unfortunately, determining the energy value of a corn residue bale is not as simple as submitting a forage sample to a laboratory. Corn residue bales are extremely heterogeneous. Traditional laboratory measures used to estimate energy value can be misleading with corn residue, because husk and stalk can have relatively similar ADF fiber concentrations but very different digestibility. When whole, unground bales are fed, the nutrient composition of the bale is not necessarily the nutrient composition of the diet the cow consumes. Cows sort through corn residue and preferentially consume the more digestible husk and leaf while leaving much of the cob and stalk behind. In our research, approximately 47% of conventionally baled and 38% of EZBale residue offered in round-bale feeders was left uneaten as waste or refusal. 

Even with this selection, untreated baled residue did not provide enough energy or protein to meet the requirements of a pregnant cow. As shown in Table 1, the nutrient deficit was greater for conventionally harvested residue than for EZBale residue. The bottom line is that feeding corn residue bales free choice is not the same as grazing corn residue. While some selection occurs, intake is limited, and both energy and protein supplementation are needed. 

Ammoniation can substantially improve corn residue 

When hay is expensive, ammoniation can make harvested corn residue a much more useful forage resource. Treatment with anhydrous ammonia increases both the crude protein concentration and digestibility of low-quality crop residues. Ammoniation substantially improved the feeding value of both types of corn residue. It increased crude protein concentration from an average of 5.6% to 10.8% and increased digestibility. However, harvest method still mattered. As shown in Table 1, ammoniated conventional residue provided adequate protein for a cow in mid-gestation but still required additional energy. In contrast, ammoniated EZBale residue provided enough energy and protein to meet estimated requirements in mid-gestation. By late gestation, both required additional energy, but the amount needed was considerably less for ammoniated EZBale residue. Thus, ammoniation improves corn residue, but it does not eliminate differences created by harvest method. The combination of harvesting less stalk and ammoniating the resulting residue produced the greatest feeding value. 

For more information on the process and economics of ammoniation, see Ammoniating Crop Residues and Ammoniated Corn Residue Equal to Medium Quality Grass Hay? 

Remember nitrates in drought-stressed corn 

Drought-stressed corn can accumulate nitrate, particularly in the lower portion of the stalk. Drying and baling do not eliminate nitrate, making nitrate concentration an important consideration when residue comes from severely drought-stressed fields. Again, how the residue is fed matters. When cattle graze corn residue, they preferentially consume leaf and husk and eat relatively little of the lower stalk, where nitrate concentrations tend to be greatest. Cows fed whole bales also have some opportunity to sort and avoid stalk. Grinding removes that ability to select. If high-nitrate stalk is ground and incorporated into a ration, cattle consume it along with the other plant parts. Consequently, nitrate testing is particularly important when drought-stressed residue will be ground and included in a mixed ration. Testing the total diet can help determine risk, and in many cases a higher-nitrate corn residue can be safely utilized by diluting it with feeds that are lower in nitrate. 

Purchased bales can also bring weeds 

When corn residue bales are purchased and moved from another farm or region, they may also bring weed seed. During drought, when feed may be sourced from a wider geographic area than normal, this risk deserves consideration. Think about where purchased residue will be fed before distributing bales across the operation. Feeding imported bales in a limited area makes it easier to monitor for new weeds and control them the following growing season. A dry lot, cropland field, sacrifice area, or another location where weed control is practical may be preferable to spreading purchased bales throughout clean native range or multiple pastures. The goal is to minimize the area that will need to be monitored and potentially treated if a new weed is introduced. 

Use corn residue strategically 

Whenever practical, grazing standing residue is generally the best option because it takes advantage of the cow's ability to selectively harvest a higher-quality diet while leaving much of the lowest-quality stalk in the field. When residue must be harvested, capturing more husk and leaf and less stalk improves the value of the resulting feed. Untreated baled corn residue will generally require both protein and energy supplementation. Ammoniation can substantially improve its feeding value. Combining ammoniation with EZBale produced a feed capable of meeting the energy and protein requirements of a mature cow in mid-gestation in our research, while ammoniated conventionally harvested residue still required additional energy.