Drive-over piles have become popular storage systems for many livestock operations today, but too often this silage never makes it from the pile to the feed bunk.

This loss in feed is commonly referred to as “shrink” and is measured by subtracting the total tons of silage fed from the total tonnage ensiled. It is estimated that about 20 percent of the silage in the country is lost to shrink every year at a steep price to producers.

According to the National Agricultural Statistics Service, the U.S. produced more than 113 million tons of corn and sorghum silage in 2011. The loss to shrink is expected to top $1.30 billion.

However, it is possible to achieve a shrink loss of 10 percent or less in properly managed piles – there are producers out there doing it.

All it takes is a “game plan,” sound management and attention to detail. Here are four important steps, which will help minimize shrink loss every time.


0712fg_forage_folks_11. Proper shape of drive-over piles
Shape drive-over piles using a 3:1 ratio. This means that for every vertical foot, there should be three feet of horizontal on the back, front and each side.

The pile should also be packed from back-to-front and side-to-side. Too often producers disregard this rule because they are trying to put too much silage into too small of a space. As a result, silage piles have side slopes of one to one or less and tower 20 to 25 feet or more above the ground.

In addition to being unsafe, there is no way a tractor operator can pack the sides. A 10 percent shrink is impossible with these types of piles and producers cannot afford not to find the extra space.

Properly shaped and sized piles are also safer for producers and their employees – reason enough to properly shape and size piles.

2. High density
Shape alone will not ensure a low shrink loss in drive-over piles. Producers must shoot for a silage density of at least 15 to 16 pounds of dry matter (DM) and 44 to 48 pounds of fresh weight per cubic foot. There is an inverse relationship between silage density and shrink loss. The higher the packing density, the lower the shrink loss will be.

If producers increase density by two or three pounds of DM per cubic foot, that will translate to a reduction in shrink loss of about three to five percentage points. Improving density alone could lower shrink loss to about 15 percent for many producers.

Two of the best management practices for achieving a higher density are to increase the number of tractors and spread the forage in uniform layers that are six inches thick or less. A tool is available from the University of Wisconsin-Madison that can help predict packing density. Click here to download the spreadsheet.

If you are satisfied with a density of 12 or 13 pounds of dry matter per cubic foot, then a 10 percent shrink loss is not going to happen.

0712fg_forage_folks_23. Excellent cove
Unfortunately, poorly covered silage bunkers and piles continue to be a major culprit for shrink loss. Poor covering accounts for the loss of $260 to $460 million in corn and sorghum silage inventory every year.

University research and field trial results show that an oxygen barrier film can cut shrink loss in the outer two to three feet of silage by 50 percent or more compared to standard black-and-white plastic.

Pay attention to the term “oxygen transfer rate” or “OTR” and use a product that provides as close to 100 percent oxygen barrier protection as possible. When examining a commercial product, be sure to ask for its oxygen transmission rate and any independent lab test results that back up the product’s oxygen barrier claims.

Another added benefit to oxygen barrier film is that it clings to the surface of the silage, filling in the gaps. Standard plastic covers trap oxygen underneath, which increases the amount of visible spoilage compared to oxygen barrier film. It is also unsafe to pitch spoiled silage.

The only realistic option is to prevent surface spoilage from happening and oxygen barrier film can do that. Oxygen barrier film pays for itself every time and reduces total shrink loss by at least two to five percentage points.

4. Team meetings
Producers should host team meetings with the parties involved in their silage operation. Include the crop growers, silage contractors and key employees.

Engage everyone in the meeting so each person knows what to expect and takes ownership of his or her roles. Team meetings are the only way to ensure a safe and efficient silage program – they are also a key part in reducing shrink loss.

Each of these steps will help you to properly shape, pack and cover drive-over piles, which in turn will reduce shrink and improve your bottom line. Click here for more information.

Ruth E. Bolsen is the managing director of Keith Bolsen & Associates.



Keith Bolsen
Professor Emeritus of Animal Sciences
Kansas State University.