Is corn silage a forage? The answer is yes and no. About half of the corn plant is grain and about half is forage, making corn silage a unique forage. The corn plant is highly productive, so yields of dry matter are greater than about any other forage, about two times that of alfalfa.

IT'S COMPLICATED: The economics of silage use are a bit complicated. Market prices are routinely available for corn, alfalfa and grass hay, but that is not the case for corn silage. (Photo: UNL BeefWatch)

In the distant past, corn silage was commonly used as a forage for cattle, because of the large yield of nutrients per acre. The wet silage also added moisture to otherwise dry feedyard rations. With the advent of the ethanol industry, most cattle in Nebraska feedyards are fed wet byproducts like distillers grain or gluten feed. Therefore, the moisture from corn silage was not needed and the distillers grains provided more protein than needed. Cattle feeders then replaced silage and alfalfa with inexpensive baled cornstalks.

About six years ago, we realized we were harvesting high-moisture corn, which was stored in a silo, and then baling the residue after it dried. It seemed logical to just harvest the two together as corn silage. That logic led to five years of intensive research on corn silage.

Some of the research has been directed to the use of corn silage as a substitute for corn grain in finishing diets for feedyard cattle. This research was conducted 40 years ago. The difference today is the availability of distillers grain. Corn silage can replace 30% to 45% of the corn grain in finishing rations when 25% to 40% distillers grain is fed. Feed efficiency declines some as the silage level increases, but that is offset by the lower cost of the silage.

The other important use of corn silage is as a primary energy source for growing (backgrounding) calves or for beef cows. (Corn silage has good value for dairy cows but I will leave that for more qualified experts to discuss). Again in the distant past, we fed rations of 90% corn silage and 10% soybean meal to growing calves, and they gained 1.8 to 2 pounds per day. When distillers grain became readily available, we fed 15% to 30% distillers grain and 80% to 85% corn silage, and the calves gained 3 pounds per day. That caused us to take a closer look at the protein in the corn silage. We found there was much less "bypass" protein in the silage than we had believed previously. Distillers grain is an excellent source of "bypass" protein and complements the corn silage very well.

The economics of silage use are a bit complicated. We have market prices for corn, alfalfa and grass hay reported routinely. That is not the case for corn silage. Typically, corn silage is priced based on corn grain price, because the alternative for a farmer is to just harvest the crop for grain. Therefore, we choose to price silage based on the price of corn grain in the field. Corn price typically increases from harvest to the following summer, and the increase is roughly equivalent to storage cost. So the value of corn grain in the field is equal to fall price minus harvest costs.

If the cash price for corn in October is $2.86 per bushel, then the value in the field is $2.39 per bushel, and silage is about $20.44 per ton at 38% dry matter. Silage harvest removes more plant nutrients than accounted for in the grain. However, if manure produced from feeding the silage is applied to the field, then the net is a value of $3.54 per ton, pricing the silage in the field at $16.90. The cost to the cattle producers for harvest, storage and manure spreading is $15.83 per ton for a price at the silo of $32.73. With a 10% shrink in the silo, the silage ready to be fed would be $36.37 per ton. Obviously, the shrink and manure credit are very important to the economics.

One method for comparing values of forages is to calculate the cost per unit of energy. In this case, I am using total digestible nutrients. Using the prices listed above, silage would cost roughly 7 cents per pound of TDN. Corn grain would be just under 8 cents, and distillers grains would be 6 cents. Hay at $70 per ton would be just over 8 cents. These estimates suggest corn silage, especially when fed with distillers grain, can be a very economical forage.

The use of corn silage for feedyard cattle, backgrounded cattle and cows was thoroughly discussed at a conference on June 17. The information can be accessed at beef.unl.edu/silage-beef-cattle-conference.

Klopfenstein is an animal science professor emeritus, Watson is an assistant research professor, and Erickson is an Extension beef feedlot specialist at the University of Nebraska-Lincoln.