Specialist Gives Tips to Assure Quality Corn Silage

MOUNTAIN GROVE, Mo. — University of Missouri Extension dairy specialist Ted Probert says this is a good time to review management practices to harvest good quality silage.

He offers the following tips:

Prepare the storage structure. Empty, clean and inspect bunkers and towers for structural damage. If storing in bags, choose and prepare a hard-surface site in a well-drained area. This preserves the silage’s quality and makes it easier to feed.

Harvest at the right stage. Harvest when dry matter (DM) content is right. Chop corn at the following dry matter content percentages for best results: 30-35% for bunkers, 32-37% for conventional tower silos, 40-45% for limited-oxygen silos and 35% for silo bags. Estimate DM content by looking at the kernel milk line, says Probert. The best level is when kernels reach the 1/2 to 2/3 milk line stage.

For more accuracy, chop 10 corn plants and run them through the chopper. Measure DM with a moisture tester or microwave oven. Silage harvested too soon (moisture too high) results in poor fermentation, nutrient loss through seepage and poor animal performance due to low consumption.  Dry plants, caused by delayed harvest, result in difficult packing, molding and overheating.

Chop at the proper length. Chop length should be short enough for easy packing but not short enough to compromise effective fiber in animal diets. Probert suggests an average length of cut range from 3/8 to 3/4 inch for unprocessed silage and 3/4 inch with a 1-2 mm roller clearance for processed silage.

Fill correctly. This is a critical step, especially for bunkers, says Probert. Line the inside walls of the silo with plastic prior to filling to reduce seeping and spoilage. Fill the silo quickly and pack well. Packing increases the density of the pile. Tighter packing results in greater oxygen exclusion and better fermentation. Shoot for a target packing density of at least 14 pounds per cubic foot. Consider fill rate and vehicle packing weight. To calculate packing weight for filling a bunker, use this equation: Optimum packing vehicle weight (lbs.) = filling rate (tons/hour) 800.

Cover the silo. Cover the silage pile to reduce spoilage and increase digestibility. Cover with 5 mm plastic, or consider oxygen barrier film for optimum oxygen elimination. Hold the cover in place with at least 15 to 20 tires per 100 square feet.

Inoculants may improve silage quality. There are two types of silage inoculants — fermentation aids and spoilage inhibitors. Fermentation aids rapidly lower pH. They work best with crops with low amounts of fermentable carbohydrate, such as grass or alfalfa. Crops like corn silage that are prone to aerobic spoilage benefit from spoilage inhibitors. These products can extend the bunk life of silage.

Consider running a silage fermentation analysis. After silage ferments, do a fermentation analysis to judge how well your harvest and storage procedures worked. This analysis shows the types and amounts of acids produced during fermentation and the quality of fermentation during the silage making process.  “Data of this kind can be valuable in identifying aspects of harvest and storage practices that could be improved in future harvest seasons,” says Probert.