Dry matter loss at feedout is a function of the face removal rate, meaning how many inches per day you remove from the face. If you’re removing a small amount, then dry matter losses tend to be quite high.
The denser the feedout face is, the lower the porosity. If you have a low packing density, then you will have a high porosity, which allows oxygen to penetrate more deeply into the face. If your removal rate is only a few inches per day, then the silage is exposed to oxygen for an extremely long period of time, which will significantly increase your dry matter losses.
“Sizing the storage is critical to assure face removal rate as relatively high,” said Brian Holmes, Ph.D., Emeritus Professor at the University of Wisconsin. “I recommend aiming for at least 12" per day removal rate as part of the sizing process.”
If you size for 12" per day removal rate, and change your feeding practice to half that removal rate, you still can be at a reasonable removal rate. Whereas, if you size for 6" per day, and cut your removal rate in half, then you're down to 3" per day. It's important to size the storage initially to make sure you have the removal rate that's going to minimize the losses, Holmes said.
Pulling Back Plastic
Remove the plastic covering from enough silage for no more than three days’ worth of feeding. Then weigh down the edge of the remaining plastic so the wind can't blow underneath it, to prevent oxygen from penetrating the silage under the plastic. Gravel-filled bags work well to help seal it. Or try doubling up the number of edge-touching tires that remain on that area of the plastic, to help hold it down.
“Next, remove and throw away any spoiled feed under the plastic,” said Holmes. “That's additional dry matter loss that has occurred.”
When removing silage from the storage face, it’s important to maintain a smooth face without creating fissures, to minimize exposure to oxygen, said Holmes.
If you are using a bucket to remove silage from the face, then scrape the edge of the bucket down the face to accumulate the forage on the floor.
“It's not a particularly fast process, which is why people tend to try to ram the bucket into the face and then lift up. This can create fissures or cracks in the silage, providing a way for oxygen to penetrate the face faster than [with] a tight, smooth face,” he said.
Another option is with a facer/defacer, a rotating drum on a front-end loader. It mills or grinds the forage off the face, with the forage falling to the floor. This process also can be relatively slow.
A faster technique is a silage rake. It's a fixed tine rake that fits onto the front-end loader. It uses a series of tines that leaves a corrugated face as opposed to a smooth flat face. “This increases a surface area that's exposed to oxygen, so you might end up with a slightly higher dry matter loss as a result of a non-smooth face,” Holmes noted.
During the face removal process, remove no more silage than will be fed at that feeding. Excess feed left on the floor for extended periods will decompose faster than feed in the tight face, due to excess oxygen exposure.
Think Safety First
Silage removal occurs so often that workers sometimes forget the dangers involved; so Holmes says, don’t forget to remind your farm workers and family members on a regular basis to consider the following:
Falling From the Top – Stay back from the face when pulling the plastic back and removing poor-quality silage from the top of the silage. Also, if an avalanche occurs and you are on top, the risk of injury is great. Even limiting the amount of plastic pulled back to an amount covering less than three days’ worth of feed will not protect you against falling, if an avalanche occurs while you are standing on top of the silage.
Avalanche Fall Zone – While on the floor of the storage in front of the face, stay back at least three times the height of the face, to remain outside the avalanche zone.
Equipment Safety – When the feedout face is taller than your equipment, place a bar screen over the outside of the windows, to keep the silage from breaking the windows and to protect the operator in the event of an avalanche.
Overhanging Silage – Do not build a bunker or pile higher than your unloading equipment can reach; that would create a forage overhang, increasing the risk of an avalanche that could bury the unloading equipment or anyone working near the face.
Taking a Sample Safely – Scoop removed feed into a bucket, then drive the loader away from the face, a distance at least three times the height of the face, and only then take the samples from the bucket.