For most dairies, feed remains the largest expense, and corn silage continues to form the foundation of the ration. That makes it worth taking a closer look at what shapes silage performance and where management decisions can improve return.
On a recent Dairy Signal episode, John Goeser, dairy nutrition and management consultant at Progressive Dairy Solutions Inc., and Luiz Ferraretto, assistant professor and Extension specialist in dairy nutrition at the University of Wisconsin-Madison, , walked through how corn silage management is evolving. Their discussion covered feed hygiene, chop height, and other management decisions in the field and at feedout, and how those choices connect back to cow performance and milk production.
Their focus stayed on understanding how agronomics, harvest decisions, and feeding management show up in the bunk and ultimately in the tank. Rather than chasing trends, the goal is to evaluate what works within each farm’s system.
Back to Basics: Fiber and Starch
Many producers are taking a closer look at what defines good corn silage. Ferraretto brings the focus back to the fundamentals that drive performance in the ration.
“From a corn silage perspective, I think there are two main things we need to focus on,” he says. “First is fiber and the other is starch.”
Fiber and starch together often make up close to half the plant. But total nutrients alone do not tell the full story. What matters is how much of those nutrients the cow can actually use.
“If we talk about fiber, we need to understand digestibility,” Ferraretto says. “And if we talk about starch, we need to understand digestibility, because having a nutrient there but not being available does not help us either.”
Goeser says it’s easy to focus too narrowly when evaluating forage quality.
“We are enamored with discussing fiber digestibility,” he says. “But it is only one component. There are really four components that drive forage quality with corn silage and equate to the milk per ton we’re ultimately going to look for.”
Those include fiber content, fiber digestibility, starch content and starch digestibility. Looking at all four together provides a clearer picture of how a crop will perform in a ration.
He also encourages producers to think beyond forage quality alone and consider total return.
“We need to take into account the agronomic costs and considerations, the acres needed to feed the herd, as well as the intake and milk production in our economic scenarios,” Goeser says.
Feed Hygiene: An Overlooked Limiter
Even high-quality silage can fall short if feed hygiene isn’t managed well. Spoilage yeasts, molds, mycotoxins and other unwanted organisms can be introduced at harvest or develop during storage and feedout.
“Feed hygiene includes all the anti-nutritional components that can show up in forages or in the ration when it’s fed to cows,” Goeser says. “Even when forage quality is good, spoilage organisms can still be present. Those microbes can disrupt rumen energy use and reduce performance, almost like water in diesel fuel.”
Ferraretto points to yeast as a common concern in corn silage systems.
“If there’s a lot of yeast contamination for whatever reason, you should expect lower milk production,” he says. “That can be tied to lower intake, reduced palatability and also impacts on fiber digestibility.”
One of the challenges is that spoilage is not always obvious.
“These are not things we can see,” Goeser says. “We need laboratory testing. Infrared cameras can also be very helpful, because when we’re talking about yeast, we’re really talking about spoilage yeast.”
He notes that yeast counts can range widely across farms, sometimes reaching tens of millions of colony-forming units per gram.
“If we have 10,000 or even 30 million CFU per gram, that means there can be millions of yeast organisms in just a small amount of feed,” Goeser says. “Now think about how much of that feed a cow eats every day, and how quickly that adds up.”
Ferraretto adds that controlling contamination starts with basics in harvest and storage. Clean surfaces, good packing, and consistent feedout all help reduce spoilage risk. Soil, dust and manure contamination can add to the problem.
“A lot of different avenues could act and compromise some of the hard work that you put into preparing that silage,” Ferraretto says.
Managing Stability at Feedout
To help limit spoilage, both Ferraaretto and Goeser point to inoculants and organic acids as tools that can support stability under the right conditions.
For corn silage, Ferraretto highlights Lactobacillus buchneri–based inoculants.
“The Buchneri type inoculant shift fermentation towards acetic acid at a certain point,” he says. “Acetic acid actually delays the proliferation of these molds when we are feeding cows after opening the silo.”
Better stability can show up as reduced heating at the bunk and more consistent intake.
“If you’ve ever been to a feed bunk, put your hand in the TMR, and you saw that the TMR is very warm and the cows don’t want to eat, that’s what we’re talking about,” Ferraretto says.
Goeser adds that the benefit can extend beyond the bunker and into the TMR.
“Silage has a longer shelf life,” he says. “It can really be valuable… so much so that it can carry into the total mix ration and actually increase the shelf life of the total TMR to a measurable amount.”
For wetter forages, inoculants alone may not fully control spoilage. Organic acids may be part of the solution.
“I usually think about propionic acid as the potential savior when you have all that silage warming up,” Ferraretto says. “You can kind of stabilize that for palatability a little bit.”
Application rate matters if you want to see a real response. Too little product won’t move the needle on stability or spoilage control, even if the ingredient itself works.
“One or two pounds per ton isn’t going to make a difference,” Goeser says. “Fifteen to twenty pounds per ton would be equivalent to what a fermentation would create.”
Chop Height: A Measurable Tradeoff
Chop height is one of the most direct ways to influence fiber digestibility, but it comes with a clear yield tradeoff. Ferraretto shares results from a meta-analysis that breaks down the impact in numbers.
“For every 10 inches of increase, you have about 2.5 percentage units increase in NDF digestibility, about the same amount increase in starch, but then you have a half ton decrease per acre in dry matter yield,” he says.
On an as-fed basis, that equates to roughly 1.5 tons per acre lost for every 10-inch increase in cut height.
Goeser says that tradeoff deserves attention.
“To me, that’s something that we should be looking at each year,” he says.
Response depends heavily on crop conditions. More mature corn tends to benefit more from higher chop height, while immature corn shows less response. Drought-stressed fields are generally less suitable.
“Drier plants benefit more than immature plants when you are increasing chop height,” Ferraretto says.
Field conditions also play a role. In fields with disease pressure or significant lower canopy dieback, leaving more of that material in the field can improve forage quality going into the silo.
“If we had a diseased field, it may be beneficial to raise that cutter head up just to limit some of that less digestible material,” Goeser says.
Connecting the System
Corn silage performance comes back to how the whole system works together. Hybrid selection, plant health, soil fertility, harvest timing, and feed management all influence what ends up in the bunk and in milk production. Ferraretto and Goeser emphasize that no single decision drives results on its own.
For dairy producers, the opportunity is in seeing how these pieces fit together across the season and not treating any one of them in isolation. Small improvements in multiple areas can add up over time, and measuring how those changes show up in intake, milk production, and overall feed efficiency helps fine-tune decisions year after year.
