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United States Department of Agriculture

Agricultural Research Service

Title: Bunker Silo Unloaders: An Economic Analysis

Authors
item Muck, Richard
item Rotz, Clarence

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 10, 1996
Publication Date: N/A

Interpretive Summary: Horizontal or bunker silos are used on many farms to store wet forages as silage for later use by cattle and sheep. These silos are most frequently emptied using a bucket attached to a tractor, skid-steer loader or wheel loader. Such methods of unloading a bunker silo leaves a rough silage surface, making the silage more prone to spoilage. An alternate approach to unloading bunker silos would be a machine which mills a smooth surface. However, such unloaders are considerably more expensive. Can the extra expense be justified? The value of a milling-type unloader on a typical 100-cow Michigan dairy farm was assessed using DAFOSYM, a simulation model of the dairy forage system. The milling-type unloader was predicted to improve dry matter recoveries 0.5 to 3.7 percentage units in alfalfa and 0.3 to 1.5 percentage units in corn silage dependent on silage densities and bunker unloading rates. The improvement in dry matter recovery and quality attained increased the annual net return from $275 to $4,815. Under good management, increases from a milling-type device were on the order of $400 to $750 per year. This savings would justify an additional investment of up to $6,000 for this equipment if labor and energy requirements for silo emptying were not affected by unloading method. These results suggest that the farmer could afford a milling-type attachment to a tractor or skid-steer but not an independent, milling-type silo unloader.

Technical Abstract: In the U.S., bunker silos are most frequently emptied with a skid-steer loader or other bucket unloader, which leaves a rough silage face. The value of a milling-type unloader on a typical 100-cow Michigan dairy farm was assessed using DAFOSYM, a simulation model of the dairy forage system. The milling-type unloader was predicted to improve dry matter recoveries 0.5 to 3.7 percentage units in alfalfa and 0.3 to 1.5 percentage units in corn silage dependent on silage densities and bunker unloading rates. The improvement in dry matter recovery and quality attained increased the annual net return from $275 to $4,815. Under good management, increases from a milling-type device were on the order of $400 to $750 per year. This savings would justify an additional investment of up to $6,000 for this equipment if labor and energy requirements for silo emptying were not affected by unloading method. These results suggest that the farmer could afford a milling-type attachment to a tractor or skid-steer but not an independent, milling-type silo unloader.

Last Modified: 10/25/2014
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