Spoilage and waste have traditionally been part of the management game for bunker silos. One contributing factor: Using a loader to remove feed from the silo often leaves a ragged face where oxygen can work its way into the silage and set the spoilage process in motion.
Tim Kane, a dairy producer milking 350 cows near Denmark, WI, tackled the problem head-on last year by adding a silage facer to his equipment inventory. Rather than tug at big clumps of material in the bunker with a high-powered loader, he now uses the facer (attached to a skid steer) to shave about 3" of material at a time from the silage face.
Once enough material for a day's feeding has accumulated on the silo floor, Kane follows up and loads his mixer using the skid-steer bucket.
“It leaves a nice, smooth surface along the whole face of the bunker,” he says. “You don't get that air in there.”
Similar technology has been used widely in other parts of the world for more than a decade, points out Keith Bolsen, silage specialist at Kansas State University. But mechanical facing has only caught on in this country during the last three to five years.
“On the whole, we (U.S. producers) do a below-average job of face management, and faces that are too large only make the task more difficult,” says Bolsen. “This is desperately needed technology.”
A number of companies are selling the units under a variety of names, including Bunker Facer, Silage Master and Bunker Buster. Most feature hydraulics-operated rollers or drums fitted with knives, rounded points or hook-and-auger flightings.
Cost for facer units typically is in the $3,000 to $5,000 range.
Kane figures it takes 15-20 minutes daily to face enough corn silage and haylage for his herd.
“It adds a step to the process, and a little bit to overall feeding time (compared to using the loader),” he says. “But if it keeps that bunker face nice and smooth, it's well worth it.”
Kane says the effects of using a facer are especially noticeable when feeding out of a split bunker setup. He has several bunkers that are 80' wide and usually works one 40' face at a time.
“With a loader and bucket, you always have that rough edge along the side face,” he says. “With the facer, you work the material in front of you and on the side and keep everything smooth and well packed.”
There's also an advantage on the feeding end, says Kane.
“With a loader and bucket, you can end up with some clumps and clods in the feed that don't always get broken up in the mixer. With the facer, you're breaking those up as you go. You definitely see a difference when you lay the feed out in front of the cows.”
An initial concern for dairy producers using facers was that the rolling-cutting process might reduce silage particle length — especially alfalfa haylage — in total mixed rations. Doug Sutter, Brown County, WI, extension agent, measured particle lengths of silage removed from bunkers by different kinds of facers.
“We found no evidence that the bunker facing systems reduce particle length,” he reports.
One key to getting the most out of a facer, says Sutter, is to work the bottom third of the silage face first.
“If you start at the top and work down, you get a kind of ski-hill effect as the material falls off. You end up not facing the bottom,” says Sutter.
Some producers might want to add depth gauges to prevent running their facers into the concrete silo floors, he says.
Sutter adds that, while facing can promote more uniform mixing and delivery, it can also disguise poorer-quality feed during the loading process.
“You still have to avoid the tendency to mix spoiled feed with good feed,” he says.
The best bunker silos are narrow with high sides and both ends open, says Bill Kautz.
Build bunkers as narrow as possible, advises Kautz, director of product development and technical services for Chr. Hansen Biosystems, Milwaukee, WI.
“This minimizes the surface-to-volume ratio in the structure and can result in a significant reduction in dry matter losses when the silo is properly managed,” he says. “When designing new bunkers, plan to feed 6" across the entire face on a daily basis.”
The sides should be as high as possible, but not so high that the top of the silage mass can't be reached by available unloading equipment.
“Building walls higher than unloading equipment will make it much harder to manage the face properly on feed-out and can result in dangerous overhangs,” says Kautz.
For above-ground bunkers, it's best not to put in a back wall, he adds. That's because it's difficult to pack chopped forage along that wall and in the corners.
“This usually leads to excessive spoilage and dry matter loss in the last 10-15',” he says. “Not building a back wall will reduce bunker capacity slightly but will allow good packing of the entire silage mass. It also gives the operator the option of feeding from both ends, if desired.”