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Mining for gold in your silage

Progressive Dairyman Editor Lynn Jaynes Published on 06 February 2015

Much of the western U.S. is dotted with old gold mining sites. While some of the mines followed veins, much of the gold was actually obtained through placer mining – the process whereby stream-bed gravel is scooped into a round pan and gently swirled or agitated until the gold sinks to the bottom of the pan and the gravel is gently washed over the sides. It was hard work. You had to want it bad.

Manure – yes, manure – can also be mined. It’s not anything you’re going to want to write home to Mama about, but you can mine some very interesting information there, like finding what gold (corn) was processed in the cow and what passed through without being utilized.



But what if you could mine the manure before it became manure? That would be even better, right? Well, you can. You can mine the silage in the field to determine how well the kernels are processed, which will in turn tell you how available the nutrients are to the cow, and it’s a lot like placer mining.

You’ll need a bucket holding about 1½ gallons of water. Take four or five handfuls of fresh silage and dump it into the water. Swish it around. The leaves and husks will float, and you can pour off this material. If you use this “wash and rinse” procedure three or four times, on the final rinse-out you’ll find the corn kernels have floated to the bottom.

Now assay your gold and determine its value. How can you tell if it’s well processed? A full 95 percent of the kernels should be cracked (nicking or crushing is not adequate alone), each cob should be broken into eight or more pieces, and a full 70 percent of the kernels should be equal to or smaller than one-third to one-quarter of the original kernel size.

And no cheating here; if you don’t think that kernel would fit into a hole the size of a paper-punch (one-fifth of an inch), then it’s not well processed.

Good kernel processing is vital to making those nutrients available to the cow. Your silage may test high all day long on paper, but unless the nutrients are available to the cow, you might as well leave it in the field. So how do we achieve a high-quality silage?


Dr. Limin Kung from the University of Delaware stated in a recent DAIReXNET webinar ( Forage Fermentation: How to make good silage ) that a high-quality silage should maximize nutrient recovery from the field, have high nutritive concentration (in crude protein, starch and energy) and be highly digestible by rumen microbes.

In order to obtain that, it’s important to understand there is a high correlation between harvest quality and silo management as it relates to silage quality at feeding.

In short, you’ll have three opportunities to maximize your silage quality – by managing it from the field, during harvest and with silo management. Three shots. And if any of the three are lacking, the quality will be poor at feedout. The ugly truth is that three out of four times, we’ll have poorer feed quality.

Managing silage quality from the field

Nobody recovers quality lost in the field – not even through great harvest and silo management. It’s import to make sure harvest is timed right. As the plant matures, there is a rapid decline in starch digestibility in the cow because of the prolamin starch matrix.

Optimal dry matter (DM) content range for corn silage harvest is between 30 and 40 percent. A range of 32 to 36 percent whole-plant DM provides good starch content and digestibility, good fiber and good packing in the silo.


Chopping too early (less than 30 percent) results in silage with low starch and energy content, excess acid and seepage. Chopping too late (greater than 40 percent dry matter) ultimately results in silage low in starch digestibility, low in acid production, poor aerobic stability and is tougher to pack.

Managing silage quality during harvest

Another important factor is to set chop length at harvest. This will affect cud chewing, which is important for cows to keep the rumen-buffering capacity in a healthy range. Checking the chop length regularly in the field is the only way to know for sure what’s going into the silo. If you check chop length in the silo in January, it’s too late.

If you use a Penn State shaker box to assess chop length, the top layer should contain only 3 to 8 percent, the middle layer 45 to 65 percent, the lower level 20 to 30 percent, and the bottom pan should retain less than 5 percent.

Kernel processing is another facet of the harvest to manage. A higher level of processing reduces sorting and improves silage packing. Additionally, cracked kernels expose the starch contents, which equals greater digestibility. The goal is to have less than 3 to 4 percent fecal starch, as each 1 percent unit decrease in fecal starch equals 1 pound more milk.

Using the shaker technique, more than 70 percent of the starch passing through the screen is optimum, 50 to 70 percent is average, and less than 50 percent is inadequately processed (For information on the corn silage processing score process, see Cumberland Valley Analytical Services ).

Since preserving nutrients from the field constitutes the goal, applying inoculants at the chopper can help achieve a faster fermentation. Silage fermentation is aided by the right type of lactic acid-producing bacteria, and even the best forages don’t have sufficient numbers to achieve this.

Thus, adding these bacteria ( Lactobacillus plantarum ) produces a faster pH drop, less protein breakdown and lower losses. However, if two inoculants contain the same type of bacteria, it doesn’t mean they will necessarily perform equally.

How can you tell which will perform better? Ask the company for published data from independent publications that support their data. If face management or packing density are challenges, then Lactobacillus buchneri can help preserve silage quality during the feedout phase. It improves aerobic stability and results in less spoilage.

If the harvest passes quality tests in the field, the next thing to worry about is filling the silo quickly and tightly. Prepare the silo with plastic on the sidewalls; even concrete sidewalls can allow air to enter through cracks.

Pack the silage in small layers (6 to 8 inches) so it packs well, and pack it tightly (14 to 16 pounds DM per cubic foot). Then cover the bunk quickly with oxygen-barrier plastics – white plastic is better than black, and 6-mil is better than 4-mil. Then weight the plastic and secure the edges, placing more weight on seams and edges.

Managing silage quality during feedout

Once the silage makes it into the silo or bunker, nutrient preservation becomes “the war of the bugs” – good bugs (lactic acid bacteria) versus the bad bugs (yeast, mold, clostridia, enterobacteria) – and the good bugs must win.

To achieve this, we want to get the fermentation and stabilization to occur as quickly as possible. However, a good front-end fermentation does not automatically lead to stability during storage and feedout; a high concentration of lactic acid or low pH alone does not automatically equate to stabilization if silage is exposed to air.

Even if you get it into the silo correctly with good harvest conditions and get good fermentation, but the silage is exposed to air, then quality is lost. When silage is exposed to air, it’s a domino effect signaling the beginning of the end.

The only way to stop the chain reaction is to eliminate exposing the silage to air or limit the number of yeast so that the chain reaction occurs at a slower pace. Some producers will think that because they invested in a face shaver, they’re in good shape.

The truth is, a face shaver doesn’t overcome poor face management. Face shavers are most useful when silage density is low or feed rate is slow. The good news is, if used correctly, they may save 3 percent in DM loss.

Good face management, however, means a lot more than buying a face shaver. While there is no magic number for inches removed from a silage face, it’s important to remember to keep the face clean, minimize face damage and knock down only enough silage to feed that day.

Wrapping it up

I know, I know – you’ve heard this all before. I just wanted to remind you that it’s gold your panning for. It’s so easy to look at that pile and think it’s only manure, or it’s only a silage bunk. But it’s not. There’s gold in there – real gold. But to find it you’ve got to quit looking at it as a pile of manure and only a silage bunk. You’ve got to want it bad. PD

lynn jaynes

Lynn Jaynes
Progressive Dairyman