Corn silage tends to feature better fiber digestibility when the crop experiences dry-but-not-too-hot growing conditions prior to tasseling. So far, 2015 has been wetter than ideal for many forage growers, setting up the crop for some potential fiber digestibility issues.
The good news is that the rains began after most growers got corn into the ground. Plants emerged and stands were established by the time the skies opened in the month of May.
"Generally, the weather conditions from emergence until tasseling have the greatest impact on fiber digestibility," says Tim Hageman, a DuPont Pioneer dairy specialist based in Iowa. "Weather after tasseling tends to affect grain fill and starch levels more than it influences fiber digestibility."
Timing is everything: While dry conditions in early summer may actually improve neutral detergent fiber digestibility (NDFD), dry periods during reproduction and grain fill can reduce starch levels.
"In 2015, we got the crop planted and saw fantastic emergence and stand establishment in northeast Iowa. In May, we got significant rainfall, but it hasn't been wet enough to cause concern yet about digestibility levels," Hageman says. "If it remains wet and warm through June and early July, we may face some digestibility issues."
Hageman says growers have some decisions to make if wet conditions extend through June. Unless they need the tonnage, they can raise chop height to remove the least digestible fiber components in the field. This can help balance starch and digestible fiber in the silage.
"Some growers will cut 16-20 inches off the ground," he says. "This raises both starch levels and fiber digestibility. However, growers are giving up roughly a ton of forage per acre for each 4 inches of stalk they leave in the field."
Hageman suggests scouting fields 3-4 weeks before harvest and testing plants. This can give growers information about the ideal chop height for the level of starch they want to target.
"Knowing the composition allows growers to make an informed decision about whether or not to raise chop height," he says.
Growers and their nutritionists also should consider the nutritional profile of any haylage they're incorporating in the ration. Does it provide enough energy that they can chop at a lower height without impacting animal performance?
A grower who needs tonnage but is dealing with low NDFD can benefit from DuPont Pioneer fiber technology. Using Pioneer® inoculant 11CFT can uncouple lignin in the fiber that binds cellulose and hemicellulose, making these fiber sources more digestible.
"Growers need to pay attention to their fields and understand how weather impacts NDFD and starch levels," Hageman says. "They can make appropriate plans to manage their forage crops to get the most of the nutrients available."