With current high corn prices, cattle feeders should be open to all options when it comes to reducing feed costs.
When high fuel prices for both harvest and corn drying are taken into account, it is not only important to look at cutting feed costs, but also controlling the costs of harvest and drying as well. Corn earlage, which basically consists of the grain, cob, and usually the husk of the corn plant, can help with all of these considerations.
Earlage is a valuable feedstuff that contains both roughage (husks and cob) and concentrate (corn grain). In this way it is similar to corn silage, though earlage has an advantage in that earlage harvest leaves the stalk and the leaves in the field.
Estimates of corn earlage nutrient value will vary, but in general earlage will contain approximately 8-10 percent crude protein, 8-12 percent acid detergent fiber (ADF), 58-62 Mcal/100 lbs net energy for gain (NEg), and 78-82 percent total digestible nutrients (TDN).
For reference, whole corn grain generally contains approximately 85-89 percent TDN and 65-69 Mcal/100 lbs NEg, and corn silage contains approximately 68-72 percent TDN and 44-48 Mcal/100 lbs NEg, so earlage basically falls between the two in terms of energy value.
Harvesting earlage is usually done with a forage harvester with a snapper head and kernel processor. The kernel processor allows for greater digestibility and a heavier packing density.
One key harvesting consideration is moisture. A good target is to plan
earlage harvesting around when normal high moisture corn harvesting would take place. At this time, kernels have reached physiological maturity and black-layer stage, and kernel moisture will be between 28-34 percent moisture with total earlage moisture between 34-40 percent moisture.
Visually, there is often green stalk remaining on the bottom of the corn plant at this moisture. This results in a final product that is approximately 60-65 percent dry matter. Drier earlage can still be useful, but digestibility and energy value will be decreased.
A breakpoint of 25 percent kernel moisture is advised. If the kernel is less than 25 percent moisture (total earlage moisture of approximately 30 percent), digestibility, palatability, kernel integrity, and fermentability may be severely affected.
Ensiling of earlage occurs similar to that of corn silage. Packing density is recommended to be between 30-33 lbs dry matter/cubic foot. Earlage with recommended kernel moisture concentrations of greater than 28 percent will be fully fermented in approximately 2-3 weeks, though it is recommended to wait up to two months before beginning to feed new-crop earlage. In many cases this may not be feasible, but a wait of at least 3-4 weeks is advised.
Earlage yields will vary widely, and will depend heavily on the amount of corn on the cob. Because the cob and husk make up approximately 20 percent of the dry matter weight of earlage, earlage harvest will yield approximately 20 percent more dry matter than corn grain yield.
Data from Pioneer Hi-bred estimate a 200 bushel/acre corn yield to be equivalent to a six ton (dry matter basis) earlage yield. This equates to just over nine ton/acre earlage yield if the earlage is 35 percent moisture.
The same Pioneer analyses estimated a 150 bushel/acre corn yield is equivalent to a 4.6 ton dry matter/acre earlage yield, or just over seven tons/acre yield of 35 percent moisture earlage.
Various pricing strategies for earlage are available, and most are based on current corn prices. The method used by this author is to first assume a dry matter and energy content of harvested dry corn. Many different values can be used for this, but typical estimates are approximately 85 percent dry matter and 67 Mcal NEg/100 lbs.
The next step is to put corn price on a per ton basis. This can be done by taking corn price divided by 56 and multiply by 2,000. Then, take the corn price per ton multiplied by earlage energy value (in Mcal NEg/100 lbs) divided by 67 (the assumed energy value of corn in Mcal NEg/100 lbs). Take this answer divided by 0.85 (the assumed dry matter content of dry corn).
Finally, take this answer multiplied by the dry matter content of earlage.
For example, if corn is $6.50/bushel and earlage harvest yields a 59 Mcal/100 lb NEg earlage with 65 percent dry matter, the equivalent price would be calculated like this:
Step 1: Convert corn to dollars per ton ($6.50/56)*2000 = $232.14/ton
Step 2: Multiply corn price per ton by earlage energy equivalent
$232.14*(59 Mcal NEg/67) = $204.42
Step 3: Divide Step 2 answer by dry corn dry matter, assumed to be 85
percent 207.52/0.85 = $240.49
Step 4: Convert to as-is pricing by multiplying by earlage dry matter
content $240.49*0.65 = $156.32
For this example, earlage would be valued at about $156/ton based on $6.50 corn and earlage with 59 Mcal NEg/100 lbs and 65 percent dry matter.
Because earlage contains approximately 75-80 percent corn and 20-25 percent roughage on a dry matter basis, it can fit very well into backgrounding rations as the primary feed ingredient. Earlage can be utilized effectively in finishing rations as well.
A very simple feedlot ration of (dry matter basis) 65 percent earlage, 30 percent modified distillers grains, and five percent supplement can be utilized and should result in gains and efficiency approaching those found with conventional rations containing corn, distillers grains, and corn silage or hay. This would result in a ration containing 13-15 percent roughage, which is more than is typically fed in finishing rations.
To reach a ration with 10 percent roughage, 50 percent earlage could be included with five percent supplement and the balance of the diet consisting of concentrates such as corn or distillers grains. The roughage portion of earlage is finely processed, which has led to some questions about whether or not a coarse roughage source should be included to prevent digestive problems such as acidosis.
Some nutritionists recommend including approximately one pound of coarse roughage, such as hay, straw, bean stubble, or corn stalks in earlage rations. However, in well-managed feedlots where acidosis is typically not a problem, earlage should be able to serve as the sole roughage source.
More information on this and many other beef-related topics can be found on the U of M Extension Beef Team's website at www.extension.umn.edu/beef or on the Beef Team's Facebook page which can be found by searching for the University of Minnesota Beef Team.