This article will focus on bunker management during storage and feed-out. Dry matter (DM) losses are usually due to aerobic degradation, environment and/or poor structural surfaces. One of the quickest and easiest ways to prevent dry matter losses in a bunker situation is to ensure that the top seal (cover) has not been compromised.
Any punctures should be taped immediately to prevent further spoilage. A weekly inspection is necessary to ensure there is no further damage due to birds, animals or other causes. This inspection can save tonnes of spoiled feed annually.
The next area vulnerable to loss is the amount of exposed top surface area. The ideal practice would be to cut the plastic each day or at each feeding, thereby minimizing exposure. This is not always practical or feasible, so producers should not expose more silage than what will be used over the course of three days. Prior to exposing the silage it is recommended that producers refer to the five-day weather forecast. If heavy rains or winds are forecast it is best to cut only what is required prior to the unsettled weather. Wind and rain can result in substantial losses (DM and nutrients) and the additional moisture can definitely influence rations by altering the 'as-fed' component of the feed.
Bunker face management definitely influences DM losses. Poor management can lead to excessive levels of spoilage and DM losses. Properly sizing bunkers to ensure six inches of removal daily has been found to keep DM losses to 3% or less, depending on the silage density (Homes and Muck, 2000). The feed-out face should be kept smooth to ensure the least amount of exposed surface area. A smooth surface will also prevent areas where birds can perch, feed and soil the feed below. To achieve a smooth finish, a mechanical defacer is highly recommended. Defacing should be done at each feeding with the intent of removing only the silage required. High levels of oxygen exposure and weather (rain and wind) will increase spoilage (DM loss) in piles of silage not used during feeding. If a mechanical defacer is not feasible, then producers should remove silage by dragging the bucket down the pile. Lifting up the pile can result in increased fracturing deep into the pile. This fracturing provides an entrance for oxygen resulting in further and prolonged spoilage. Temperature is directly correlated with spoilage and DM losses so increased bunker management is necessary during the warm season.
Following these guidelines will definitely improve feed quality, animal health and ultimately profitability.
References: Holmes, B.J. and Muck, R.E. 2000. Preventing Silage Storage Losses. University of Wisconsin-Madison. Bolton, K. and B.J. Holmes. 2004. Management of bunker silos and silage piles. University of Wisconsin-Madison.