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Conventional silos do a better job
Cows produce more milk when fed out of a conventional concrete stave, top-unload silo than a bottom-unload oxygen-limiting structure ů such as a Harvestore«ů according to a first-ever long term University study comparing the two methods of storage.
Dairy specialist Howard Larsen of the University of Wisconsin compared two dairy herds over a period of 4 years. One herd of 20 cows was fed from a bottom-unload Harvestore and the other herd of 20 cows from a top-unload stave silo. Over the term of the studies he found cows produced nearly 2˘ lbs. more milk per day when fed from the conventional silo, due primarily, to the better nutritional content of the forage. Larsen told FARM SHOW the biggest problem with Harvestores, and other similar structures, is the use of bottom-unloaders and the center-fill method used to fill the structures.
"All silos are oxygen-limiting but the key is in how you handle the material once it's inside the silo. Bottom unloaders let oxygen into the silo which damages the quality of the forage," says Larsen. "Also, when you centerfill, you get a solid mass in the middle and it stays soft around the outer edges, which traps air. Distribution of silage as you fill has as much to do with the quality of feed as anything. We've found we can greatly improve quality by packing silage as we fill and we can also get 20 to 40% more silage in a silo."
The University of Wisconsin owns several Harvestores, including one at the Marshfield experiment station that's been there for 30 years. "We've never seen any practical advantage to this type of structure. In fact, they've always been a problem," he told FARM SHOW.
For a complete copy of Larsen's research report, contact: FARM SHOW Followup, Dept. of Dairy Science, University of Wisconsin, 266 Animal Sciences Bldg., Madison, Wis. 53706.


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1986 - Volume #10, Issue #6