Mike Hutjens, University of Illinois extension dairy specialist, suggests three scenarios for fall forage harvesting.

“We have plenty of late-planted corn and soybeans, which could be nipped by an early frost,” says Mike Hutjens. “It is important that dairy producers understand the alternatives and strategies should this occur.”

One scenario involves late-harvesting corn silage, weighing differences between yield (tons of dry matter per acre) and starch content.

“Allowing the corn crop to try to reach optimal maturity is recommended. Wait to harvest as long as the plant is growing,” he advises. “Growing degree days in the fall and a killing frost will be factors that determine how mature your corn is when harvested.”
Harvested immature corn silage at 30-34% dry matter (DM) should be stored in bags, bunkers or piles. Drier silage, at 35-40% DM, should be kept in vertical structures, depending on height and diameter of the silos, to minimize seepage losses.

Whether you buy immature corn for silage depends on the price of the standing crop, harvesting costs (lower yields and wet conditions can increase them) and potential storage losses, which could be high due to seepage and improper fermentation.

“When pricing standing corn silage, estimate or weigh the dry matter harvested – weighing silage box or truck loads, for example – and agree on price per ton, such as $45/ton for 33% dry matter,” he says. “If the silage is wetter – do not buy water – or lower in starch content, the price needs to be lowered.

“Testing immature corn silage for starch, neutral detergent fiber (NDF), acid detergent fiber (ADF) lignin, soluble nitrogen, and NDF digestibility (NDFD) will allow for optimal ration balancing,” Hutjens says. “Sugar content and NDFD may be improved, as the stalk will not contain as much indigestible fiber and sugars are not converted to starch.”

Another scenario in some areas involves harvesting immature corn as high-moisture corn. Hutjens calls it “an excellent grain alternative for dairy and beef cattle. It avoids high drying costs, allows for earlier harvest, and minimizes ear drop and weather risks.

“High-moisture corn can be stored in a silo, plastic bag or bunker. Depending on herd size, feeding 6” from the surface can maintain quality and avoid mold and yeast formation.”

Wet corn can be harvested as high-moisture shelled corn at 26-30% moisture; high-moisture ear corn at 28-32% moisture; or snaplage, which is the ear, husk and parts of the corn plant, at 35-38% moisture.

“Inoculants for wet corn are recommended to improve fermentation,” he says.

As a third forage option this fall, Hutjens suggests immature soybeans. Because of late planting and flooded areas, some soybean fields won’t reach maturity and may be available for purchase. “Immature soybean forage will be similar to alfalfa/legume forage and should be harvested by a similar approach – cut, wilted and harvested at similar moisture levels based on your storage unit. It should be stored in bags, bunkers or in vertical silos.”

Harvesting soybeans at the pod-formation stage will optimize yield – 1-2 tons DM/acre – and quality – 18% crude protein and 0.55-0.60 Mcal/lb DM. “Harvesting earlier will reduce yield,” Hutjens cautions. “Avoid leaf loss/dropping that leads to lower protein content and dry matter yield. Inoculating soybean silage is recommended.

“Green soybean seed will feed similar to regular soybeans, but can be lower in oil and nutrient content. Heat-treating wet and immature soybeans will require more heat and energy to improve rumen-undegraded protein (RUP) levels. Check herbicide labels for restrictions if the soybeans have been sprayed.”