Drought conditions across much of Nebraska have left pasture and hay supplies in short supply, leading cattle producers to consider grazing standing corn as an alternative feed source for the remainder of the summer, fall and winter. At the same time, corn prices remain below the cost of production, creating an opportunity for some growers to market their crop through livestock rather than grain sales.
Nebraska Extension says standing corn can provide a high quality, energy-rich forage source when managed properly. The approach may be especially attractive for cow-calf operations facing limited pasture availability or high hay prices.
For drought-stressed corn that has been released by crop insurance, grazing can provide value, but producers should first review herbicide labels for any grazing restrictions. Nitrate accumulation also can be a concern in drought-stressed plants. Extension recommends that cattle not be turned into fields while hungry, allowing them to begin by consuming developing ears and upper portions of the plant before gradually grazing lower stalk sections where nitrate concentrations tend to be higher. Providing abundant clean water also helps reduce nitrate risk.
Protein levels in vegetative corn are generally higher than in mature plants, although supplemental protein may still be needed depending on crop maturity and cattle nutritional requirements.
Even healthy, green corn fields can provide a competitive feeding alternative when pasture is limited. Strip grazing allows producers to better utilize standing forage while reducing grain intake and the risk of acidosis as ears develop. Cattle are typically allocated two to three days of forage at a time, with producers targeting 60% to 80% grazing efficiency.
Extension estimates cattle will consume about 2.5% to 3% of their body weight in dry matter each day. Producers grazing cow-calf pairs should account for both cows and calves when determining forage allocations. Supplemental protein also may be needed as the crop matures.
Managing strip grazing requires temporary electric fencing, with rows often flattened using an ATV or other equipment to prevent cattle from pushing standing corn into fences. Extension also recommends preparing multiple grazing sections in advance to reduce the risk of cattle entering the entire field if fencing fails.
Researchers at the University of Nebraska have also found virtual fencing to be an effective tool for managing strip grazing of annual forages, reporting livestock containment rates above 98%.
The economics of grazing standing corn depend on several factors, including alternative feed costs, harvest expenses, fertilizer value returned through manure and urine, opportunities to establish additional forage crops and water availability.
Using Nebraska Extension's example, a 200-bushel-per-acre irrigated corn crop valued at $4.75 per bushel, plus $30 per acre for residue grazing, generates a gross value of $985 per acre. After accounting for approximately $94 per acre in avoided harvest and hauling expenses and an estimated $125 per acre in retained nutrient value, grazing would need to generate about $766 per acre to match the crop's value.
Based on an estimated 25 tons of forage per acre at 65% moisture during the optimum silage harvest window, and assuming cattle consume 60% of the crop's dry matter, Extension estimates feed costs at about $145 per ton on a dry matter basis, or about $125 per ton on an 85% dry matter hay equivalent basis. Additional fencing, supplements and management costs would increase the total feeding expense.
For mature standing corn grazed during fall and winter, Extension recommends limiting cattle access daily to reduce the risk of overeating grain and developing acidosis. Allocation should be based on estimated grain yield and cattle nutritional requirements.
In one example, 100 dry, pregnant cows grazing a 200-bushel-per-acre corn field would require about 0.15 acres per day to consume approximately 13 pounds of grain each. Because corn residue alone may not provide enough fiber, producers may need to supplement with additional forage. A balanced supplement containing vitamins, minerals and, if needed, protein, along with the ionophore Rumensin, also can help meet nutritional requirements and improve feed efficiency.
Although grazing standing corn has not traditionally been common across Nebraska, Extension says current drought conditions, expensive hay supplies, lower corn prices and advances in virtual fencing technology have combined to make it a practical feeding strategy for producers evaluating alternatives for their cow herds this year.
Source: University of Nebraska-Lincoln, "Cows Grazing Standing Corn – A Feed Option for this Summer, Fall, and Winter"