Milk your corn silage for all it's worth

Corn silage is a staple in dairy and beef animal diets across the US, providing valuable nutrients for growth and performance. As summer is rolling by and the new crop is beginning to mature, taking some time to think through the harvest timing and process could prove valuable in strategizing to put the most digestible forage in front of your animals over the coming year. Unlike alfalfa, we typically aren’t looking to feed corn silage for the protein content, but rather as an energy source. As we look at the needs of a dairy cow in particular, the greatest nutrient need, next to water, is energy. I recommend a few key harvest planning points as farms start itching to get the new crop corn silage harvested and into storage for fermentation to do its work.

Balancing the Diet

Since the quantity of energy required is so high and often the most limiting in the diet, corn silage is a key piece in the diet puzzle to help meet that requirement. Corn silage can provide energy through several avenues: fiber digestibility and starch or sugar - making it a great forage for many ruminants. But what determines high-quality corn silage? Considering what is to gain from on-farm forages may help determine this answer.

If not available from forage, sufficient fiber digestibility [Neutral Detergent Fiber – NDF] is very difficult to achieve in a diet - unlike protein and starch that can be added quite easily. Striving for the greatest fiber digestibility in forage crops will pay dividends in cutting feed costs and optimizing health and performance. While this part of planning must be done much sooner than harvest prep, producers have many options in terms of hybrid selection to help provide the best balance of fiber digestibility, starch, and starch digestibility in corn silage. 

Moisture Levels

Harvesting at the right moisture is likely one of the most influential factors when putting up corn for silage. Moisture plays a critical role in packing and fermentation, which are important when trying to preserve the forage’s nutrients. I recommend working closely with an agronomist and nutritionist to develop the right protocols for achieving ideal moisture levels that align with the specific harvest situation and storage type. Keep in mind that harvesting too wet or too dry can compromise your forage in a number of ways, including lost nutrients during fermentation and less available or undigestible nutrients, while increasing the chances of molds, yeast, and mycotoxins.


Starch levels and starch digestibility are important pieces of high-quality corn silage. Harvesting too wet (immature) leaves starch underdeveloped – providing suboptimal energy. Harvesting too dry can make that same starch too hard for the animals to digest and utilize. While higher starch values are nice, but if it is not easily utilized by the animal, it is passing through – which doesn’t help much. This conundrum leads to another important area to review when preparing for corn silage harvest: starch digestibility. Checking fecal starch today can provide information about how last year’s crop performed, and what changes may be needed for this year.


Harvesting at the correct moisture will help with starch digestibility but processing kernels appropriately is another key component. Check kernel processing score (KPS) during harvest to ensure that the starch in the corn silage is broken optimally. There are several ways to access your processing score and a laboratory can provide feedback quickly to help determine whether the settings on the processer need adjustment. While KPS will typically increase over time in storage, shooting for a KPS of over 70 at harvest is a good mark to aim for.

Corn silage is a diet staple and a large contributor of energy for ruminants. Taking time to review and plan out harvest timing and procedures this fall can ensure that the crop you harvest is the best it can be, in terms of energy available to the animal, over the next year. Doing so will pay dividends in both optimizing performance and reducing feed costs.

By: Cliff Ocker, Rock River Labaratory, Inc. 

Tags: Corn Silage, Nutrition