Ever wonder which method of preserving silage - bunkers, bags or piles - is the most economical? Kansas State University experts asked that same question a few years ago and developed a procedure and an Excel spreadsheet to help producers make informed decisions.

They first compared the per-ton cost of silage stored in each of the three methods using an example dairy, says Kevin Dhuyvetter, Kansas State University ag economist. Besides including the cost to produce, harvest, store and feed the silage, the researchers provided a milk-production-adjusted cost to account for any impact the silage may have on milk production.

Their findings: The cost per ton was lowest for silage stored in bags – if all bunker fixed costs were included in the comparison. The cost of storing in piles was similar to the cost of storing in bags.

"However, if bunker fixed costs were ignored, which might be appropriate in the short run if a bunker already exists, and milk production was the same for all storage methods (i.e., silage quality was equal), bagged silage actually had the highest cost," Dhuyvetter says.

"Dairy producers need to recognize that many factors will influence which silage storage system is best for their operations," he adds. Major influencers include the environment - rainfall, temperature, etc., and a dairy's physical layout and land availability.

Since the KSU study was completed in 2005, several changes have occurred, he says.

"Relative costs of different systems are some things producers need to check out. I haven’t checked on costs of bags, but given how many more producers are using them for forage and grain, their price has possibly increased faster than costs associated with bunkers and piles." That, Dhuyvetter says, is a possible strike against bags.

The value of silage is much higher since 2005 and systems better at preserving quality and minimizing shrink or loss are more valuable. Those factors, he says, favor the use of bags. As does recent California research by Frank Mitloehner, University of California-Davis. His study indicates environmental concern associated with certain gases released from silage bunkers or piles, which could have repercussions if regulations are put in place. Bags, again, would be preferred because they minimize area exposed to air.

Although bags might be more “environmentally friendly” with regard to gases released, disposal of plastic can also become an environmental concern potentially, he points out.

"Bottom line, it is especially important for each producer to evaluate what is most economical for their operation given their resources and constraints. That is, the framework/spreadsheet we developed is still very applicable, but producers need to plug in their own numbers rather than rely upon our assumptions."

To help producers evaluate storage alternatives, visit www.AgManager.info and click on Livestock & Meat Marketing: Production Economics, scroll to "Dairy" and download the pdf and Excel files after the heading "Bunkers, Piles or Bags: Which is the most economical?"

Another interesting part of the KSU work was a listing of the advantages and disadvantages of each of the three storage systems. Click here for the list.