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The five most common silage mistakes

Jim Mattox Published on 14 August 2013

Albert Einstein said, “Anyone who has never made a mistake has never tried anything new.” Farmers can relate to this since farming requires constant innovation and experimentation.

Farms are like snowflakes – no two are ever the same – but one thing that is the same on every farm is the science of fermentation.

Making silage is a fermentation process and whether you are bagging grass in Tillamook, building a huge drive-over pile in South Dakota or making baleage in New York the science of fermentation does not change.

While fermentation science remains constant, one thing that varies from farm to farm is the science of management. Next to managing employees, managing the silage harvest is perhaps the biggest management challenge of all.

Detailed planning and great communication are the keys to success. Very often it is not the things that are done right, but the things that are done wrong that have the most lasting effect.

As much as one-third of the nutritional quality of your feed can be compromised from harvest to feedout, so it is important to avoid costly mistakes. These are what I think are the top five most common silage-making mistakes.

Harvesting at the wrong moisture or maturity
Premature harvest is probably the most common silage mistake, especially with corn silage. Harvesting corn at above 70 percent moisture is a major misstep. It is hard to get a good fermentation at this moisture level.

Additionally, the kernel has not yet fully developed, so harvesting prematurely will result in reduced starch levels. Add a poor fermentation on top of this, and the losses add up.

Solution: Harvest corn silage when the kernel’s milkline is no less than half and preferably closer to two-thirds. Keep in mind that the milkline is just a starting point, and an actual moisture test should be done to hit the optimal harvest window.

If using custom harvesters, make sure to have a planning meeting with them far in advance of harvest to discuss the importance of your crop being harvested at the right maturity.

How to measure: The most accurate way to determine dry matter content is through a forage lab, but it can take awhile to get the results back. There are three ways to determine moisture on the farm: Koster tester, microwave and an electronic tester. Each method has pros and cons, but choose one and use it multiple times daily during harvest.

Insufficient kernel processing of corn silage
When processing corn silage, the goal is to break up the kernels, reduce particle size and create more surface area for the rumen microbes to access and utilize the starch – greatly increasing dry matter and starch digestibility.

Kernel processing is often not done to the degree that is necessary. Completely obliterate the corn kernel. Don’t just crack it.

Solution: Set the roller mill 1 to 3 mm apart, and maintain this setting throughout the harvest. Monitor the feed coming into the silo, and if whole or partially cracked kernels are observed, then adjust your rollers.

A rudimentary way to measure the distance between rollers is with the blade of a pocket knife. The rollers should tighten down against the blade of the knife, or they are too far apart. Optimal processing requires more fuel and rollers need to be replaced regularly, so if hiring a custom harvester, agree ahead of time what is expected. Understand that doing it correctly will cost more but yield a higher return.

How to measure: The simplest way to monitor processing during harvest is to take a 32-ounce cup and fill it with chopped corn. Then empty the cup and count how many half kernels and whole kernels remain.

If there are more than three half or whole kernels remaining, then optimal processing has not been achieved. Check the feed coming from each harvester once per hour as it is delivered to the silo. Some commercial feed labs also offer kernel processing scoring as a service.

Inadequate packing
Packing silage is the most critical element to making good silage. Oxygen is the enemy and packing removes oxygen from the silo. Drive-over piles are increasingly popular but are often poorly designed with sides that are too steep, resulting in poor dry matter densities.

Solution: Fill and seal the silo as quickly as possible, but pack each ton of silage for two to three minutes with at least 800 pounds of packing tractor. Pay close attention to packing technique.

The thinner the layers are spread, the easier they will be to pack. Spread silage 6 inches or less for maximum compaction. Make sure the packing tractor is packing all the time, even while the trucks are unloading.

After the chopping has stopped for the day, continue packing until all of the feed harvested that day has been packed tightly. Cover silage as quickly as possible with a high-quality plastic.

How to measure: Compaction can be measured with a bunker density tester once the silo is opened. A bunker density test will measure the pounds of dry matter per cubic foot. The goal is to achieve at least 16 pounds per cubic foot across the entire silo face.

Incorrect use of inoculants
Effective silage inoculants enhance fermentation by quickly lowering pH and preserving nutrients. Every crop that goes through fermentation should be treated with an effective silage inoculant.

Many producers still don’t use silage inoculants, and this is very costly. In many cases, they have used a product in the past that was not effective, or they could not see the difference. Others may have purchased an effective product, but they did not apply it correctly and therefore did not realize the benefits.

Solution: It is important to remember that all silage inoculants are not created equal. In the U.S., there are no regulations on the viability of organisms. Make sure to do your homework and select an inoculant that is backed by a reputable company and supported by university research.

Silage inoculants should be applied at the chopper and according to label instructions. Any other method will reduce the effectiveness.

How to measure: Send a sample to a forage lab, and have a fermentation profile test performed. Discuss the results with your nutritionist to determine if a fast, efficient fermentation was achieved.

Characteristics to look for in an effective fermentation are a low pH level and a good lactic to acetic acid ratio (at least three-to-one).

Poor feedout management
Feedout is the last phase of fermentation and often the most overlooked. This is the phase when the silage is removed from the silo and fed to the cattle. Up to 50 percent of total dry matter losses can occur during this phase.

The cause of this loss comes from the re-introduction of oxygen into the silo. Whenever the silo is opened and the feed is exposed to oxygen, losses will occur.

Yeast is naturally present in the environment and in the presence of oxygen yeast will consume carbohydrates and produce heat, both of which are undesirable. Molds also contribute to dry matter losses at feedout and can produce harmful mycotoxins that cause health and reproduction problems in cattle.

Solution: Design your silo with the smallest face possible, and build it so the daily removal rate will be at least 6 and preferably 12 inches per day, ensuring that fresh silage is always being fed.

Use a mechanical facer or loader to “shave” the face of the silo from the top down. This will reduce the exposed surface area to air and minimize damage from oxidation.

How to measure: Heat is the primary indicator that silage is spoiling and losing nutrients. A compost thermometer can be used to measure the silo face or loose feed in the commodity area. The latest tool available is thermal imaging technology, which captures a silo’s heat variation and can help determine problem spots.  FG

References omitted due to space but are available upon request. Click here to email an editor.


Jim Mattox
Feedtech Solution Manager
DeLaval, Inc.