Brian Vaassen and Mike Hutjens recommend welcoming the New Year with a thorough checkup of this year’s corn silage.

“Quality is optimized if the crop remains in storage for three to four months. Fermentation’s complete, the kernels are softer and more digestible and some moisture’s been reabsorbed,” says Vaassen, a dairy nutritionist and sales manager for Vita Plus, Madison, WI. “Plus, the holidays are over, most of the book work is done and it’s a good time to reflect on what worked and what didn’t.”

“Once you start feeding the corn silage, it’s too late to make big changes – other than some ration revisions,” says Hutjens, University of Illinois Extension dairy specialist. “But it’s never too late to evaluate what you’ve already done and to begin making plans for the next season.”

They suggest taking several samples for analysis. “If each structure – a bag, pile, bunker or upright silo – houses a different hybrid, samples should be taken from each one, but many producers are putting all of their corn silage in one big unit,” says Vaassen.

The samples should fall within the following parameters:
• Chemical analysis: starch, greater than 30%; NDF, under 42%; NDFd, greater than 55%; ADF, less than 26%; and dry matter, 30-35%.
• Kernel processing: All kernels should be damaged and the cobs should be pea-sized or smaller.
• Particle length: After a sample is shaken in a Penn State Forage Particle Separator, 10-15% should remain in the top box, more than 40% in the second box, and less than 40% on the bottom. If the separator has four boxes, 8-15% should remain on top, more than 40% in the second box and more than 25% in the third box with less than 10% on the bottom.

“But, if over two-thirds of the forage in the diet is corn silage, you’re going to need a little more length in the total diet, so 12-20% should remain on top,” says Vaassen.
• Fermentation: The pH should be less than 4, with lactic acid greater than 5% and acetic acid less than 2%. Over 70% of the total volatile fatty acids (VFA) should be lactic acid. If a Lactobacillus buchneri inoculant was applied, acetic acid could be higher.
• Packing density: 15 lbs of dry matter per cubic foot is the minimum, say the nutritionists. “I’ve seen densities in the low 20s,” says Vaassen. “The denser you can pack it, the better off you’ll be. Oxygen is an evil component of silage.”

Hutjens recommends removing 4” a day from the top of an upright concrete silo, 6-12” from a silage bag or 4-6” from the face of a pile or bunker. “I would remove another 6” to 1’ from each structure in summer,” adds Vaassen.

One final caveat: Whether you use bags, bunkers, and/or piles, walk around them once a week all year to make sure everything is structurally sound.

“If you see rodent damage, set traps, place bait and patch holes,” says Vaassen. “If tires or sandbags have slipped, put them back in place.”

See “Evaluate Haylage Before Feeding” story.