September 8, 2005

Harvest Timing, Storage Important for Corn Silage

Harvesting corn at the right time and storing it properly are vital to producing high-quality silage, according to a North Dakota State University beef cattle expert.

“Proper moisture and maturity at the time of ensiling is necessary to ensure adequate fermentation,” says Greg Lardy, beef cattle specialist in the Animal and Range Sciences Department.

The ratio of grain to stover, or roughage used as feed for livestock, changes as the plant matures. Harvesting too early results in wet silage that will not ferment properly and has greater effluent losses. Harvesting too late results in silage that doesn’t pack properly. Also, stover in silage becomes less digestible as it matures.

The type of structure the silage will be stored in determines the optimum moisture content at which to harvest the silage, Lardy says. Harvesting silage too wet increases seepage losses from the silo and reduces dry-matter yields. It also can lower feed intake in livestock. Harvesting silage too dry results in mold development and lowers the silage’s digestibility, and can result in lower protein silage.

Here is recommended moisture content for various types of storage structures:

• Horizontal bunker – 65 percent to 70 percent
• Bag silo – 60 percent to 70 percent
• Upright concrete stave silo – 60 percent to 65 percent
• Upright oxygen-limiting silo – 50 percent to 60 percent

Some loss is possible in storage structures. However, simply piling silage on the ground and packing it generally results in unacceptable levels of spoilage and waste, Lardy says.

Here are anticipated storage losses:

• Uncovered stack or pile – 20 percent to 40 percent
• Covered stack or pile – 15 percent to 35 percent
• Uncovered trench or bunker silo – 12 percent to 25 percent
• Covered trench or bunker silo – 8 percent to 20 percent
• Upright concrete silo – 8 percent to 15 percent
• Oxygen-limiting silo – 3 percent to 11 percent

Lardy also has this advice for anyone preparing corn silage this fall:

• Exclude oxygen from the silo so anaerobic fermentation can occur. Be sure packing equipment can keep up with chopping equipment. Producers may need more than one packing tractor or larger bunkers because of the capacity of today’s self-propelled harvesters.
• Cover bunker silos with plastic or over coverings to limit spoilage in the outer areas of the pile. This limits the amount of oxygen that can penetrate the pile and helps keep rain and snow from seeping into the pile.
• Monitor silage piles for evidence of deer or raccoon damage.
• Pile the silage as deep as practical for bunker silos to reduce the amount of surface area exposed to oxygen. Fill the silo as quickly as possible to limit plant respiration losses.
• Additives, conditioners, preservatives and bacterial inoculants can improve fermentation and produce a better-quality silage, but don’t let the use of these products be an excuse for ignoring the basic principles of good silage making outlined above.
• Keep knives on the chopper sharp. This will improve machinery efficiency and produce a silage that packs and ferments better.
• Develop a daily, routine maintenance and inspection program for chopping equipment.

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Source: Greg Lardy, (701) 231- 7660, glardy@ndsuext.nodak.edu
Editor: Ellen Crawford, (701) 231-5391, ecrawfor@ndsuext.nodak.edu

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