TOO COARSE, TOO FINE, or JUST RIGHT?

By Kimberlee Schoonmaker (re-printed with permission of Dairy Herd Management)

In the classic children’s fairy tale, Goldilocks stumbles across the home of three bears. Finding no one home, she helps herself to three bowls of porridge.  After finding the first bowl to be “too hot,” and the second bowl “too cold”, she finally declares the third bowl is “just right.”

Corn silage is a little like those three bowls of porridge. It can be “too coarse,” “too fine” or “just right.” Now there is a lab test called a corn-silage processing analysis that quantifies how well your silage was chopped and processed. The test was developed through a collaborative research effort between Dairyland Laboratories of Arcadia, WI; the USDA’s Dairy Forage Research Center in Madison, WI; and Pioneer Hi-Bred International.

Test results take three or four days, which makes it impractical for most producers to use the results during harvest, says Dave Taysom, director of Dairyland Laboratories, a Wisconsin based lab that offers a commercial version of the corn-silage-processing test.

However, you can still use the results to your advantage after harvest. Here are three ways to do so:

1.  TWEAK ENERGY VALUES

A corn-silage-processing analysis tells you how well the corn kernels in your silage were damaged during processing, says Dave Mertens, a USDA dairy nutritionist at the U.S. Dairy Forage Research Center in Madison, WI.  It does this by measuring how much starch falls through a 4.75 millimeter “coarse” sieve.

Ideally, you want more than 70% of the total starch in the sample to fall through the coarse sieve. This indicates “optimal” processing occurred and most of the starch can be digested by the cow without much chewing. Anything less than that is considered “average” or “inadequate.”

These results give you an idea of how well your cows will utilize the starch, or energy, in the silage.

Less than optimal processing leaves too much starch on the coarse fraction. This starch may not be well digested, which means your cows may not get the energy from the silage that you thought they would.

Adjusting the net energy value of corn silage up or down based on the degree of kernel damage is one way to use the processing values, says Bill Mahanna, GM of nutritional sciences at Pioneer Hi-Bred International. Be sure to monitor your cows closely to see how they respond to this strategy, he adds.

2.  DIAGNOSE FIBER PROBLEMS

The results of a processing analysis also tell you if the diet will contain enough effective fiber, Mertens says.

The data on particle size distribution, which also comes with the report you get back from the lab, show you the percent of “coarse,” “medium” and “fine” particles in the sample.

For example, let’s say the results show kernel processing was “optimal” – more than 70% of the starch fell through the coarse sieve. However, a substantial amount of particles – more than 25% – passed through the “fine” sieve onto the bottom pan, which indicates your silage was chopped rather finely. This combination could mean that you do not have enough physically effective fiber in the diet – especially if corn silage is the major source of fiber in your ration. In a situation like this, you may want to add more coarse fiber to the diet through baled hay.

And next year, you might not want to chop your corn silage as finely. However, if you chop coarsely and use a small roller clearance, it is possible to have less than 10% of the silage particles on the bottom pan and still have optimal kernel processing.

3.  STOP THE PROCESSING TUG-OF-WAR

Fuse the results from a processing analysis of this year’s harvest to help you fine-tune the roller mill settings on your chopper next year.

If you hire someone to chop your silage, share this year’s results with him, as well as your goals for next year. Often times, you and your custom harvester have different goals in mind when chopping corn silage. You want the processing rolls tightened as much as possible to get good processing. On the other hand, your custom operator may want to open the rolls a bit wider in order to harvest as many acres as he can in a timely fashion, Taysom says.

Remember, anything you do to improve the consistency of your processed corn silage will help improve the consistency of your entire ration.