What is Your Corn Silage Worth?

Dr. Joanne Knapp, Principal Technical Consultant, Fox Hollow Consulting, LLC, Columbus, OH

Corn silage is a valuable feed ingredient in dairy rations, and its nutritional value is based on its starch and digestible neutral detergent fiber (NDF) content and lack of anti-nutritive compounds such as molds and mycotoxins.  The starch and digestible NDF contribute to both NEl (Net Energy of lactation) and MP (Metabolizable Protein).  The amount of starch and digestible NDF in corn silage is a function of maturity at harvest, how well the ears are filled, the cutting height, and how well the silage is preserved.  Better corn silage will have more starch and less NDF (Table 1).  Because starch in corn silage generally is more than 90% digestible in the total tract while the NDF is only 40 to 50% digestible, every point of starch is worth approximately twice as much as a point of NDF on a NEl basis.  The starch contribution to MP depends on whether the starch is fermented in the rumen, providing energy for the rumen microbes to grow and produce the microbial protein portion of MP, or whether the starch is digested in the small intestine or fermented in the large intestine, neither of which contribute to MP.

Table 1.  Nutritional value of corn silage in dairy rations.  Comparisons were done at equal dry matter (DM) percentages (35%).  At higher NDF contents, starch content is reduced and is reflected in lower NFC (non-fiber carbohydrate) contents and lower predicted nutritional values.

Corn Silage Quality

NDF (% of DM)

NFC (% of DM)

August 2010 Nutritional Value*

Very High




*Predicted using wholesale feed prices and SesameIII software.

Obviously, how well the ears fill will affect the grain and starch content of silage.  However, cutting height also affects it, because the lower the stalk is chopped, the more NDF there will be in the silage.  Typically, this NDF is also of lower digestibility than the NDF in the upper portion of the corn plant.  When I was in California, it was rare to see corn silage with NDF less than 40% since most farmers chopped at 4” above the ground.  They were able to do this because fields were laser-leveled for irrigation purposes.  However, few considered that the bottom of the plant was pretty poor in terms of nutrient digestibility and availability; they were trying to maximize dry matter (DM) yield per acre.
Note that the SesameIII predicted value of corn silage is higher than the $35 to $40/ton that most producers consider to be their costs of production (seed, fertilizer, fuel, bunker covers, inoculants, etc.).  This is a reflection of the nutritional value of corn silage in comparison to other feedstuffs available in the Ohio market area.  Corn silage delivers nutrients at a lower price than most other feedstuffs.  This is important to keep in mind as you go into the harvest season. 

Minimizing DM losses in the harvesting and ensiling process means that more inexpensive nutrients are retained, and less purchased feeds will be needed in the coming year.  At 10% DM losses in average (medium quality) corn silage, nutrient losses will be $6.80/ton.  At 15% and 20% DM losses, this drain grows to $10.20 and $13.60/ton.  I don’t know many producers who would pay those price differences on purchased commodities or concentrate mixes!

Compared to May 2010, the average price of feedstuffs and most nutrients are slightly up for August.  The exception is non-effective NDF (neNDF), which was down 5.4¢/lb to –14.4¢/lb.  It is common for neNDF to be negative, as feeds that have high levels of this nutrient, such as by-products like distillers’ grains, corn gluten feed, etc., are discounted in the market relative to other feeds.  The NEl is estimated at 9.3¢/Mcal, MP is at 46.7¢/lb, and effective NDF (eNDF) is 5.1¢/lb.  Good- to high-quality, home-grown forages continue to be an excellent and inexpensive source of eNDF, NEl, and MP.  The cost of the key nutrients was estimated using SesameIII software and break-even prices of commodities and forages used in dairy rations were predicted (Table 2). 

Based on early August wholesale prices for central Ohio, feed commodities fall into three groups:


At Breakeven


Alfalfa hay, 44% NDF, 20% CP
Bakery byproduct
Corn grain, ground
Corn silage
Distillers’ grains w/sol
Feather meal
Gluten feed
Wheat midds

Brewers’ grains, wet
Cottonseed meal, 41% CP
Expeller SBM
Gluten meal
Meat and bone meal
Soybean meal, 48% CP
Wheat bran

Blood meal
Canola meal
Cottonseed, whole
Fish meal
Soybean meal, 44% CP
Soybeans, whole

The usual caveats with SesameIII™ results apply. nbsp; You cannot formulate a balanced diet using only the feeds in the Bargains column.  These feeds represent savings opportunities and can be utilized in rations to reduce feed costs within limitations for providing a balanced nutrient supply to the dairy cow.  Prices for commodities can vary because of quality differences as well as non-nutritional value added by some suppliers in the form of nutritional services, blending, terms of credit, etc.  Feeds may also bring value to a ration in addition to their nutrient value, e.g. tallow as a “carrier” and dust suppressant in vitamin/mineral pre-mixes and molasses as a source of sugars. 

The detailed results of the SesameIII™ analysis are given in Table 2.  The lower and upper limits give the 75% confidence range for the predicted Break-Even prices.  Feeds in the “Appraisal Set” are either those that were completely out of price range (outliers) or had unknown prices, such as the alfalfa hays of different nutritional quality.   

Table 2.  Prices of dairy nutrients and actual wholesale, breakeven (predicted), and 75% confidence limits for feed commodities used on Ohio dairy farms.

Table 2