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From: "... valentine53179" <>
Subject: [ILckEG] silos 3
Date: Thu, 10 Apr 2003 22:33:36 -0500


Concrete Stave Silos
Stave silos are probably the most common silo. The staves have metal hoops wrapped around them to keep the structure from coming apart due to the pressure of the silage. The hoops are spaced closer near the bottom where the pressure is greatest. This type of silo is good for storing whole plant grain crop silages like corn and sorghum and also for relatively wet hay-crop silages stored at the 55 to 65% moisture level. Stave silos cost the least of all the tower silos. Stave silos are usually equipped with a top unloader.
Silo costs and unloaders are covered more thoroughly later in this publication.


Poured Concrete Silos
This type of silo is made with a metal form. The concrete is strengthened with metal reinforcing rods embedded in the concrete. Poured silos are normally equipped with top unloaders.

DETERMINING SILO CAPACITY NEEDED
The silo capacity needed depends on how the silo is to be used and the number and class of livestock to which the silage is fed. Some operations would use the silo to carry a herd over a winter for 120 to 150 days while others would feed out of the silo throughout the year. Year-around feeding of silage is popular with some farmers because more forage can be harvested from a given area than with pasturing. Also, forage quality can be more uniform and the amount and kind of ration can be controlled.
Warm weather can cause exposed silage to spoil. In the hot humid Southeast, a farmer should remove at least 4 inches and preferably 6 inches per day from the exposed surface of the silo. More than 4 to 6 inches can be removed, but based on removing 4 inches or 1/3 of a foot, a farmer should have a minimum of 122 feet of packed silage for a 365-day feeding program. This could be two 70-foot-tall tower silos or a 140-foot-long bunker silo. More than the exact 122 feet should be provided in order to allow for settling. Refilling a silo can reduce this requirement. However, a farmer needs to be conservative when figuring how many times he will refill the silo.


Silo Unloaders
The machinery used to unload tower and horizontal silos differ considerably. Tower silo unloaders are specialized machines. Tower silo unloaders are either top unloaders or bottom unloaders. Horizontal silos can be unloaded with a multi-purpose front-end loader mounted on a farm tractor or with specialized silage unloaders.

Top Unloaders
This type of unloader loosens silage from the surface of the silage and conveys it to the center of the silo. The silage enters a blower at the center and is blown through a chute that is directed at an open door in the side of the silo. The silage impacts a metal tunnel built around the line of doors in the side of the silo. It falls down the tunnel, and is collected in a feed wagon or on a conveyor that automatically distributes the silage along a feed bunk.
One of the most inconvenient things about top unloaders is that the chute has to be changed from one window to the next lower window as the unloading proceeds. The frequency that someone has to climb up the ladder rungs on the silo doors inside of the tunnel to lower the chute depends on the rate that silage is being fed. This is a far bigger problem in the early stages of unloading a tall silo because of the height that must be climbed.


Bottom Unloaders
There are at least two designs of bottom unloaders used. The silage slips down the silo onto the rotating conveyor that scrapes silage off and delivers it to the center of the unit. The silage is then conveyed out of the silo by a conveyor located in a tunnel in the foundation of the silo. This type of unloader does not require periodic climbing up the silo like the top unloader does.
Another type of bottom unloader uses weights on the end of chains that are attached to a shaft at the center of the silo. The shaft rotates causing the chains to extend horizontally. The weights at the ends dislodge silage from the cylinder of material as it slips down the silo. The loosened silage falls through an opening in the bottom.







excerpted from:

Fact Sheet DS 54 of the Dairy Production Guide, published September, 1992, Florida Cooperative Extension Service. For more information, contact your county Cooperative Extension Service office.

at http://edis.ifas.ufl.edu/BODY_DS083

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