Missouri Dairy Business Update

Volume 16, Number 6
July 2016

Are Your Ready for Silage Season

Ted Probert

Corn silage can be an excellent source of nutrition for any class of ruminant livestock. For silage to be at its best as a feedstuff proper harvesting and ensiling practices must be followed. Since the 2016 crop will soon be ready to chop I thought it would be worthwhile to review the steps required to minimize spoilage and dry matter losses while maximizing nutritional quality of silage.

Harvest at the correct stage.

Good fermentation of silage results from ensiling at the correct moisture level. For horizontal silos moisture should be 65-70% while bagged silage can be 60-70%. These moisture levels are ideal for bacterial fermentation and also allow for adequate packing. Drier silage will be hard to pack, slower to ferment and can mold. Wetter silage can seep and may be susceptible to undesirable clostridial fermentation. Whole plant moisture content can be predicted using the milk line method. One half to two thirds milk line corresponds with ideal moisture content for harvest. Images depicting milk line can be viewed from these links: http:www.farmwest.com/images/client/Corn%20Growth%20Fig%201.JPG http://www.mississippi-crops.com/wp-content/uploads/2012/06/Milk_Line_half.png. Be sure to start monitoring the crop's progress early to avoid missing the optimal harvest window.

Chop and process correctly.
The shorter silage is chopped the easier it is to pack. Short chopped silage also results in less sorting at the feed bunk. The flip side of this coin, however, dictates that silage should be chopped long enough to provide adequate effective fiber in ruminant diets. The recommended length of chop for unprocessed corn silage is 3/8 to 1/2-inch theoretical length of chop (TLC). Optimal TLC for processed and brown midrib silage is 3/4 inch. Sharp knives will assist in achieving a uniform chop length and will also reduce energy required for harvest.

Processing corn silage will, in most cases, improve starch digestibility and animal performance. The importance of processing increases as the plant matures and characteristics of the starch fraction change. Methodology for on the farm monitoring of processing are available at this web site: http://dairyone.com/wp-content/uploads/2014/08/Aug2014Improver.pdf

Fill quickly and pack well.
A high density (15 lb. or more dry matter/cubic ft.) is important for minimizing spoilage losses. Silage should be packed using the progressive wedge method. Using this method, each load of silage is pushed up the silage face to form a slope with 30 to 40 percent grade and leveled into layers about 6 inches deep. These thin layers are one of the most important factors in properly packing the silo. Other important aspects of effective packing are the weight of packing tractors and the amount of time devoted to packing. In most cases, the packing tractor(s) should operate continually during filling. The following formulas can be used to assist with packing procedure:

Filling Rate (Tons/Hr) = Packing Vehicle(s) Weight ÷ 800

Packing Vehicle(s) Weight = Filling Rate (Tons/Hr) X 800

Example: If your tractor weighs 26,000 # you can fill at: 26,000 ÷ 800 = 32T/Hr
If your chopper can deliver 45 Tons/Hr you will need: 45 X 800 = 36,000# Packing Wt.

Cover it.
Sealing the silo is crucial to minimize storage losses and make a stable product. One Kansas study found average losses in the top 18" to be greater than 40% in uncovered bunkers. Use high quality plastic for covering. When purchasing plastic ask about its oxygen transfer rate (OTR). Higher quality plastic developed specifically for use as a silage cover will be significantly better at eliminating oxygen than traditional plastics. The suggested method for sealing a bunker silo is available at this web site: http://qualitysilage.com/wp-content/themes/twentyten/PDF/BunkerSiloManagement.pdf

Consider using a silage inoculant.
There are two basic types of silage inoculants available to producers - fermentation aids and spoilage inhibitors. Fermentation aids contain lactic acid producing bacteria that stimulate or insure rapid fermentation. This type of inoculant works best on forages containing low concentrations of fermentable carbohydrates. Results with corn silage, which is high in fermentable carbohydrate, are variable but benefits are realized in some cases. Spoilage inhibiting inoculants contain a specific strain of bacteria, L. buchneri, that improves aerobic stability of silage. This characteristic leads to extended bunk life of silage at feed out. Spoilage inhibiting inoculants will be of benefit in higher dry matter silage or if silo face management or feed out practices are less than optimal.

Evaluate your efforts.
Once silage has been harvested and completed fermentation, you may want to evaluate the job you have done harvesting and storing. A fermentation analysis can provide an evaluation of your silage preservation procedures. Information included in a fermentation analysis will include silage pH and a profile of the content of different fermentation acids present. These results can be compared against a target profile and give a good indication of the quality of fermentation that you have achieved in your silage.