Corn Silage Kernel Processing, Fact or Fiction?

Posted: March 15, 2017

The benefits of corn silage kernel processing have been replicated many times in research and at the farm level. The main advantage is breaking the corn kernels into pieces, which should result in improved starch utilization and milk production. However, are producers observing the benefits of kernel processing? Is this management practice a sure thing? Unfortunately, the information collected from Extension’s “Crops to Cow” project does not entirely support this statement.

Production Perspective

Dr. Larry Chase from Cornell reported in Dairy Business East, 2014 on corn silage kernel processing scores conducted by Cumberland Valley Analytical Services. Guidelines reported from the lab represent the percent of starch passing through a 4.75 mm screen. A kernel processing score greater than 70 percent are optimally processed, between 50 and 70 percent are adequately processed and less than 50 percent are considered inadequately processed.  Between 2010 and 2012 on 1,131 samples only seven percent of the samples were optimally processed, while 51 percent were adequately processed and more importantly, 42 percent of the samples were inadequately processed.

The Penn State dairy business management team has been working intensively with 24 dairy producers tying together finances with cropping and feeding practices. Currently, 23 farms have analyzed their 2016 corn silage. All samples were tested using wet chemistry at Cumberland Valley Analytical Services. Over the past several years producers have been surveyed on their management practices including kernel processing. Ninety-eight percent of the respondents reported having their corn silage processed. However, visual appraisal by the dairy team members suggested otherwise. In the current project funded by a Northeast Sustainable Agriculture Research and Education grant kernel processing and particle size distribution have been included in the analysis to capture more closely what is occurring at harvest. Table 1 illustrates the results to date from the Penn State project. The majority of the herds fall within the adequately processed range but there may be opportunity for improvement especially if paying a custom operator with the expectation of optimally processed.

 Table 1 March 2017

Producers on the project questioned the relationship on processing score with the starch and dry matter percent. Due to the extreme weather conditions in Pennsylvania for 2016 the corn silage starch content on a dry matter basis is ranging from 14 to 46 percent. Out of the 23 farms sampled, 16 samples are from a horizontal structure and seven from upright silos. The particle size distribution is very similar on average regardless of the structure. Due to the small sample size it is difficult to make any connections between dry matter and starch content to the kernel processing score. Researchers have started to examine these connections but it is far from absolute.  However, it always comes back to the big picture. So far, some of the corn silages that are optimally processed have extremely low fiber and/or starch digestibility. On the reverse side some corn silage with the lowest processing scores have very high fiber digestibility. The next step is to compile the production data and compare to the amount of corn silage fed along with the forage analyses. Correlations to hybrid, structure, harvest and feeding management will be examined. A financial analysis will be completed on each farm and evaluated along with forage quality, quantity, and management practices. The ultimate goal is to quantify which management practices affect the level of profitable on dairy operations over time.

Action plan for achieving optimally processed corn silage.


Include the kernel processing score on all corn silage analyses with a goal of achieving an ideal score.


  • Step 1: Discuss the CSPS results with the custom operator to examine ways to improve results.
  • Step 2: If the dairy operation has its own processing equipment, check with the manufacturer that settings are correct.
  • Step 3: At time of harvest, use a 32 ounce container to fill with corn silage. If two or less whole or half kernels are observed, this is usually considered ideal.
  • Step 4: Based on the findings, keep monitoring corn silage during ensiling to make sure dry matter or maturity are not changing and affecting results.

Economic perspective

Monitoring must include an economic component to determine if a management strategy is working or not. For the lactating cows income over feed costs is a good way to check that feed costs are in line for the level of milk production. Starting with July's milk price, income over feed costs was calculated using average intake and production for the last six years from the Penn State dairy herd. The ration contained 63% forage consisting of corn silage, haylage and hay. The concentrate portion included corn grain, candy meal, sugar, canola meal, roasted soybeans, Optigen (Alltech product) and a mineral vitamin mix. All market prices were used.

Also included are the feed costs for dry cows, springing heifers, pregnant heifers and growing heifers. The rations reflect what has been fed to these animal groups at the Penn State dairy herd. All market prices were used.

Income over feed cost using standardized rations and production data from the Penn State dairy herd.

Note: February's Penn State milk price: $19.15/cwt; feed cost/cow: $5.91; average milk production: 85 lbs.

Feed cost/non-lactating animal/day.

Feb feed cost

Download Publication

Article Details


Corn Silage Kernel Processing, Fact or Fiction?

This publication is available in alternative media on request.

Contact Information

Virginia A. Ishler
  • Extension Dairy Specialist
Phone: 814-863-3912