Cow-Calf Commentary for Iowa Cattleman Magazine
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By Beth Reynolds, Extension Beef Specialist and Erika Lundy-Woolfolk, Extension Beef Specialist
Utilizing cornstalks to lower the cow herd’s feed bill
Although Iowa has been impacted less than other states, winter feed resources are a hot commodity. Often overlooked and unutilized, nearly every Iowa cow-calf operation has a valuable feed in their backyard: cornstalks.
If fence and water resources are available, grazing cornstalks reduces stored feed costs, keeps organic matter on the field, and allows cattle to spread manure while grazing a diet that can maintain a dry, gestating cow. Cattle will selectively graze the highest quality plant parts first (grain, leaf, husk) followed by lower quality parts (stalk, cob). Because of selective grazing, coupled with weathering effects, diet quality while grazing decreases over time so take care to move fields or begin supplementing when appropriate. Tools such as Nebraska’s excel based Corn Stalk Grazing Calculator estimate how many grazing days your cornstalk acres can provide. Remember to evaluate how much down or spilled grain is present to appropriately reduce acidosis risks.
Although we are fans of the adage “a day grazed is a dollar saved,” corn residue can be utilized beyond grazing. Since we are looking at what appears to be an expensive winter feed bill, it is advantageous to understand how to best utilize baled residue for females.
Harvesting cornstalk bales for feed
While baling cornstalks can prolong feed quality into the winter months compared to grazing, the feed value of baled cornstalks is often lower than if grazing due to an increased ratio of stalks to husk and leaves. Typically, cornstalks baled before weathered average 6-8% crude protein (range of 4% - 11%), 50-55% total digestible nutrients (range of 48 - 62%) and 7-8% ash (range of 4 - 15%). Quality varies based on growing season conditions, weather post grain harvest, and baling methods.
Bale ASAP (ideally within 4 weeks) to capture the highest potential quality. Watch moisture content to avoid mold development which can be a feed quality and animal health concern. Ideal moisture of cornstalks is 15%.
Although mowing and raking tend to make baling easier, this increases the amount of dirt and ash content leading to feed palatability and animal health issues. For best results, consider disengaging the spreader on the back of the combine to make a windrow that is predominantly leaf and husks - the most sought-after components of the plant. Additionally, leaving the bottom third of the stalk in the field helps minimize erosion.
Treating cornstalk bales to improve feed value
In general, low-quality forages have high fiber and low digestibility. Treatment of cornstalks with calcium hydroxide (Ca(OH)2; hydrated lime), calcium oxide (CaO; quick lime) or anhydrous ammonia can reduce neutral detergent fiber levels, increase fiber digestibility by up to 30%, and even slightly increase protein content in some cases. With any method of treatment, use caution and wear safety clothing, gloves, and goggles when treating and handling the material.
The added cost associated with treatment, safety risks and labor requirements should be weighed in comparison to the added digestibility benefits. Strategic supplementation with untreated cornstalks may be a more cost-effective alternative in many scenarios.
Optimizing storage to minimizing waste
When already starting with a low-quality forage resource, proper storage management is critical to avoid losing more feed value.
If possible, store bales inside or cover when stored outside to minimize weathering effects and dry matter loss. Choose a storage site with good drainage and air flow, that is easily accessed in snow and muddy conditions. Research on storing round cornstalk bales has shown that bales oriented north to south in a single row, with rows spaced 3 feet apart, and stored end-to-end is best. This results in minimal face exposure, maximum drying time between moisture events, least dry matter losses, and ultimately, the best feed quality. When storing for quality, avoid the mushroom stack - bottom bale stacked face down with the top bale parallel to the ground. This scenario results in the highest feed value lost for the bottom bale as all the moisture shed by the top bale runs directly into the bottom bale, accelerating decomposition.
Pulling net wrapped bales off of frozen ground is never fun. To avoid the frustration of net wrap and bales breaking, consider building a base to set bales on. This might include a row of pallets, tires, lime or even unrolling cornstalks to build a good pad or base to better keep bales up off the ground.
Utilizing cornstalks in beef cow diets
First and foremost, due to the wide variation in cornstalk bale quality, it is advantageous to submit a representative forage test. Consider analyzing for basic nutrients (protein, total digestible nutrients and fiber) but also mycotoxins and ash content to flag any potential issues while formulating the ration. A challenge when utilizing cornstalks is the particle size. Grind stalks and include additional moisture in the ration to improve mixability and reduce sorting.
Finally, contamination of bales from dirt is nearly impossible to avoid. Since iron is a major antagonist for other vital minerals, especially during gestation, ensure cows have continuous access to a mineral program while feeding cornstalks. Organic or chelated minerals, although more expensive, have increased bioavailability and are the best option when feeding highly antagonistic feedstuffs like cornstalks and distillers grains.