Corn silage is a key component in most dairy rations, and farmers take great care to ensure the highest quality crop. After dealing with a challenging summer, farmers are preparing for the 2024 corn silage harvest.
Dr. John Goeser, adjunct professor in animal and dairy science, University of Wisconsin-Madison, said the near future looks good for dairy farmers.
“As we reflect on the growing season and near the finish line for harvesting corn for silage, there are much-needed profitable times ahead,” said Goeser. “We have all the incentive in the world to optimize the silage crop and its quality.”
Dairy cows can convert otherwise unusable calories into high-quality, nutritious animal protein and fat. “Silage quality is a function of nutrient content and digestibility – ultimately some level of energy,” said Goeser. “With corn silage, the focus is on carbohydrates.”
Weather plays a major role in corn silage quality. The U.S. Drought Monitor shows extremely dry areas in portions of southern Pennsylvania, Virginia and into the Carolinas, while New York and other Northeast states have had hot and wet weather.
“With these growing conditions, we might expect an uptick in starch content corresponding to above-average temperatures,” said Goeser. “However, wetter growing conditions seem to temper back the starch content, which could be due to lighter pollination or smaller ears, or normal ears with higher and taller corn.”
Goeser noted that temperatures during the growing season don’t typically impact rumen fiber digestibility. However, in years with above-average rainfall for the first half of the growing season, corn typically has more lignin and lower fiber digestibility.
Feed hygiene is always a concern. Goeser asked agronomists whether they were seeing ear and stalk rots, and found those issues weren’t a major concern. However, the season isn’t over and disease could still appear.
Goeser explained that disease involves three factors: favorable weather, pathogen presence and a susceptible host. Many farmers saw above-average moisture during the 2024 growing season, but thanks to improved hybrid resistance, the susceptible host might be the missing piece. He advised farmers to continue scouting for disease and remain aware of potential weather-related issues.
This year, much of the U.S. has received adequate water for corn but excessive heat – a consideration when nighttime temperatures are above average.
“Corn is interesting in that during the day, it photosynthesizes and builds starch reserves that aren’t necessarily in the grain yet,” said Goeser. “Grain-building, ear development and maturation happen at night.” During excessively hot nights, plants are stressed and don’t convert built-up photosynthate to starch.
For details on New York’s corn silage outlook, Goeser consulted with Joe Lawrence, dairy forage system specialist for Cornell University. In relating what he learned about the growing season in New York, Goeser said that much like last year, this year will likely see feed hygiene issues due to disease pressure.
“We want to do everything we can to maintain healthy plants,” he said. “Monitor disease pressure and potential for disease infestation around harvest to avoid changing the harvest window.”
Throughout New York, growing degree days and heat units have been well above average. “We’ve had heat and moisture, and unfortunately, that isn’t to our benefit for fiber digestibility,” said Goeser. “Silage is probably going to be early for some, but Lawrence stressed to not jump the gun. There’s likely wide-ranging variability following wide-ranging planting dates and how the growing season materialized with moisture.”
Lawrence mentioned the importance of proactively managing forage inventory and identifying higher quality forages. He stressed feeding forage strategically, not just working through a pile, bunker or bag because it’s next in line. He urged farmers to invest in feed storage system structures.
Lawrence suggested separate storage for high- and low-quality feeds. “We had such a wide range in planting periods that we may have two harvest intervals,” said Goeser. “If we’re stretched out three, four or five weeks at harvest, it may make sense to harvest the early stuff then cover and seal it and come back and put together a separate bag or bunker to keep the later-harvested forage separate. Don’t try to do everything at once – be more strategic and don’t follow the historical norm.”
For the rest of the Northeast, Goeser relied on input from Allen Wilder of the Miner Institute, who acknowledged the region’s excess heat. Wilder suggested rather than looking at five- or 10-year benchmarks, farmers should redefine their idea of good forage quality. Protect higher quality forage, blend it or feed it to higher potential pens.
Disease pressure for the Northeast is trending close to that of 2023. “Stage harvest and account for maturity and disease pressure,” said Goeser, emphasizing the importance of working with an agronomist and monitoring fields. “Manage risk to the extent we can and hope we don’t have a condensed harvest window.”
Mycotoxins, which are one aspect of feed hygiene, have been monitored closely for the past 10 to 15 years. Other major feed contaminants include molds and yeasts.
“In most cases, two or three issues are at play when there are digestive outbreaks,” said Goeser. “We can deal with molds and yeasts in forages provided we don’t have nutritional stressors or other spoilage bacteria such as Clostridia or Enterobacteriaceae.”
He added that minimizing spoilage bacteria and maintaining a low-stress environment for cows will help prevent catastrophes.
Optimizing harvest is a matter of accurate harvest windows and being as aggressive as possible to achieve correct moisture and maturity. Goeser urged farmers to manage risk, monitor fields and don’t get behind if disease comes in. Use forecasting tools and be prepared to harvest early if disease is imminent.
If corn is extremely tall, cut it higher at harvest to improve nutritional quality. Raising the cutter head eight to 12 inches can increase fiber digestibility because lignin is concentrated at the roots and base of the stalk. This mechanical adjustment can translate to several pounds of milk.
To preserve and optimize feed value, use an inoculant or chemical preservative. While corn silage is typically more consistent than haylage, submit samples for analysis more than once and be prepared to make changes.
“This year, more than prior years, work on data trends, not just a single observation to make decisions on how to feed,” said Goeser. “There is likely to be wider ranging quality and less consistency relative to prior years’ silage.”
by Sally Colby
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