DES MOINES -- Selecting the right time to harvest corn silage is critical to producing high-quality forage for best livestock performance. To do that, diligently monitor moisture content, say forage experts at Pioneer Hi-Bred, a DuPont business.

When plants begin to silk, record an expected harvest date on the calendar, experts suggest.

"Start walking fields and assess kernel milkline levels about four weeks after silking," says Bill Seglar, Pioneer nutritional sciences veterinarian. "Milkline levels provide a quick way to visually inspect the plant's maturity."

Seglar says when corn shows some dent on the ear, it's time to walk fields and find samples to achieve ideal dry matter at harvest.

"To check milkline, first break an ear in half," Seglar says. "Use the outer half of the ear. Remove a kernel. Either bite into the tip of the kernel or poke a knife blade or pin into the bottom and push upward until the point meets resistance. The milkline is the area from the point of resistance to the crown. One-third milkline represents 68 to 72 percent while two-thirds milkline represents 63 to 68 percent moisture."

Although some research suggests milkline as a weak indicator to actual dry matter, it complements lab testing. Milkline also can be used as a signal to start sampling dry-matter content levels. Dry-matter lab tests may provide the most accurate results. Seglar suggests collecting a minimum of 10 plants per field location to sample.

"Comparing a chipper-shredder lab sample to a grower's own silage samples helps build the data needed to make informed harvesting decisions," says Bill Curran, Pioneer research scientist. "Any dry-matter test is better than guessing. It's worth the extra effort to make sure producers get the most out of their investments."

Knowing individual field conditions and hybrid maturities also can help growers pick the appropriate harvest date. Experts recommend walking fields to examine crop maturity levels as harvest nears, helping determine if crops are on target for the expected harvest date.

Under normal conditions, the tasseling date can serve as another way to check harvest timing.

"Harvest is typically six to 10 days away when the crop is about 3-percent to 5-percent wetter than optimal," Seglar says. "Yet, it's not a hard and fast rule. Outside factors such as weather and field location can affect the rate of maturity and ideal moisture levels for harvesting forage."

Curran says growers need to evaluate on-farm storage capabilities, which can influence harvest-timing decisions, too.

If growers allow crops to reach 63 percent moisture in the field, they have the opportunity to maximize starch and tonnage yields. Harvesting below this moisture level can lower silage quality in terms of dairy performance.

Early-harvested corn silage will be lower in starch and higher in fiber content (neutral detergent fiber or NDF). Seglar says modern hybrids with strong late-season agronomics tend to retain fiber digestibility within the 63 to 70 percent moisture range.

Planting hybrids with a diversity of maturities is another way for operations with many acres to manage harvest timing.

"Staggering maturities can help hit targets for field, quality or dry matter on more of a grower's acres," Curran says. "Consider a five- to seven-day range between hybrids to allow for a shorter or wider harvest window." He says that although bigger machines allow producers to harvest in a more timely manner, there still can be limitations at the pit or storage facility, which could allow for a slip in quality at the very end.

SOURCE: Pioneer Hi-Bred.