By Gary Sliworsky
Ag rep, Emo
Last week’s article dealt with filling and packing bunker silos. This week’s continues with covering and feeding out.
Covering and sealing horizontal silos quickly is essential to avoid spoilage and dry matter loss from both air infiltration and rainfall.
Rainfall washes organic acids and soluble nutrients from the silage.
Use silage grade (UV protection) 6-mil plastic film. Dry matter losses can be 30 percent with an uncovered silo.
Plastic should be held in contact with the pile to keep air from moving under the plastic into the silage. Avoid situations where the plastic flaps and acts like a bellows to increase air circulation over the surface.
Old tires (whole, split, or truck tire sidewalls) should be placed so they touch each other. An alternative is a commercially-available system of nylon bags filled with sand or gravel.
Sealing the plastic edges can be done with soil, aglime, or sandbags. But don’t put sandbags on the wall because with “shrink” there will be an air gap under the plastic.
It is important to prevent rainfall run-off from flowing between the silage and bunker walls. Silage at the bottom corners of the pile, against the wall, often is too wet when rain water flows from the top down along the bunker wall.
This can result in too much butyric acid produced that results in poor palatability, high spoilage losses, and subclinical ketosis in dairy cows.
One way to prevent this would be to crown the silage to drain over the walls. Another way would be to form flow channels several feet from the walls and sloping them to drain off the silo surface and away from the silo.
An alternate method would be to fold the edges of the plastic back so a channel is formed to carry the rainfall run-off away without reaching the wall.
The re-exposure of the silage to air at feed-out can result in the growth of molds, yeast, and aerobic bacteria, particularly with corn silage.
Slower feed-out rates increase the likelihood of aerobic spoilage. The recommended feed-out rate is at least six inches per day.
During hot, humid weather, much larger feed-out rates are required to stay ahead of the spoilage.
Bunker silos should be sized accordingly. Do not feed moldy silage.
The silage face should remain tight and smooth to limit the penetration of air. Avoid fracturing the silo face by running at it with the front-end loader and using a lifting action.
It is preferred to minimize fracturing by scraping down the face with the front-end loader and allowing the silage to fall to the floor. Block cutters or shear buckets are other options.
Uncover and loosen only as much silage as is required.
If you suspect nutritional problems caused by poor silage quality, consider a fermentation analysis, which will measure pH, lactic, propionic, acetic, and butyric acids, ethanol, and ammonia-N.
This can be useful in diagnosing silo management and animal performance problems.