Packing it in Proper silage packing nets better feed, fewer losses

June 15, 2008 07:00 PM

Like a lot of his dairy producer clients, Green Bay, Wis. custom harvester Luke Vander Kinter can't help but whistle in appreciation at the speed and efficiency brought on by advances in forage harvesting equipment. 

Even so, he advises putting a little less emphasis on the cutting and chopping components of harvesting and a little more emphasis on good silo packing.

"You hear people talking about being able to put up 300 acres in a day,” says Vander Kinter, co-owner of Vander Kinter Farms, LLC. "It's impressive. But packing shouldn't take a back seat. That's where the quality feed (read: and ultimately more milk) is really made.”  

Other partners in this family business include his dad, Wayne, uncles Glen and Clyde, brothers Brian and Nick and wife, Kathy.

The negatives of a poor packing job can add up in several ways, according to Vander Kinter. Along with dry matter losses, poor packing can also lead to more heating (due to oxygen exposure). That, in turn, means some of the remaining feed ingredients are indigestible. "And if you do a good job of packing, you won't need to invest as much in storage,” he says.

Vander Kinter's goal when packing is "to get a lot of high quality feed in the smallest amount of space.” Density is the key.

"When we're doing corn silage, we shoot for 17 lb. (dry matter per cubic foot),” he says. "With haylage, we want at least 15 lb.”

University of Wisconsin ag engineer Brian Holmes says proper packing (achieving a density of at least 14 lb. DM/cubic foot) pays big dividends. He's teamed up with Rich Muck, of the U.S. Dairy and Forage Research Center, to develop several spreadsheets producers can use to monitor and improve density in bunker and pile silos.

Some of the key variables affecting packing density:

Tractor weight. Options for adding weight to a packing tractor include putting fluid into tires, installing wheel weights, attaching front end weights putting a concrete block on the 3-pt. hitch and adding dual wheels with fluid and/or wheel weights.

One caveat: "There are upper limits to how much weight equipment manufacturers will allow you to add while still honoring the warranty on the tractor,” says Holmes.

Using additional tractors for packing is another option. To get the greatest benefit, make sure the additional tractor(s) are at least as heavy as the first tractor, Holmes says.

Layer thickness. Holmes recommends keeping layer thickness to 6” or less while packing. Pushing less forage onto the filling face before packing or increasing the area of the filling face can help reduce layer thickness. In their "Floor Length to Achieve Bunker/Pile Silo Filling Layer Thickness Calculator” (also available at, Holmes and Muck show how different combinations of height and width of bunker/pile and dimensions of the forage transport wagon or truck affect layer thickness. 

Forage moisture content. Holmes notes a trend among dairy producers to harvest hay forages at around 50% moisture. Producers are doing this to head off potential clostridial fermentation problems and/or to offset higher ration moisture content from feeding more wet byproducts and feeds like corn silage, wet brewers grains and high moisture corn. 

But he cautions against pushing harvest dry matter content too far. Harvesting at a moisture range of 60% to 65% for haylage and 65% to 70% for corn silage yields the best fermentation. "If you harvest too dry, porosity (space between forage particles) becomes more of an issue for limiting oxygen penetration,” he says.

Total depth of silage. With higher piles, you get the benefit of self-compaction, "an under-its-own- weight effect,” Holmes says. With existing bunkers, safety concerns limit how high you can build the pile.

"If you're building new storage, though, going a little higher with the bunker walls may be worthwhile in terms of promoting better packing,” he says.

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