Flakes vs. Dry Crack
A recent review of the data of steam flaked corn versus cracked corn or whole corn has challenged the values commonly used in nutrition table. Feedlots with flaking equipment should be particularly pleased with this report. This report is also encouraging to the flaking equipment and mill equipment industries.

According to the authors of the report, "Proper steam flaking will increase the NEm and NEg values of normal yellow corn grain by 15 and 18% respectively." They report flaking disrupts the matrix around the starch granule. This protein matrix is the primary barrier to digestion of the starch of corn grain. The combined action of steaming and the shear of the rollers achieves this disruption of the protein matrix. This action improves the starch digestion in the rumen and lower tract. A word of caution: We believe, since the quality of the flakes varies with each feedlot, you should work with your nutritionist to determine the energy of your flakes.

Consistency and quality control were also emphasized the authors.

Critical Review and Peer Approved
The review and recalculation of the energy values of flaked corn were presented as an invitation paper in the Journal of Animal Science, June 2002 by Richard Zinn, Fred Owens and R. A. Ware. This group are esteemed and respected animal scientists. They accomplished an intensive review of data and recalculated the energy values compared to cracked or dry processed corn or whole corn. The information and calculations were then reviewed by other scientist (peer review) before publishing. The system adds credibility to the report.

Flakes vs. High Mosture Not Compared
In this review the comparison of flaked corn versus high moisture corn was not included in the article. Because of farming and harvesting reasons, high moisture corn is a valuable cattle feed and probably closer to flaked corn than dry processed or whole corn, in my opinion.

Why Does Steam Flaking Improve Digestability
Zinn and his co-authors make several observations. The first is the nature of the starch of corn. "The linear nature of amylose (one of the starches of corn grain) allows the starch to form very compact crystalline micelles when dried." They propose the flaking process helps to change the starch physically for the rumen bacteria to improve the digestion. They further state:

"Tight intermolecular bonding between starch molecules, along with the compact nature of the starch granules impedes rapid moisture uptake (re-hydration)." They imply the steaming process helps to moisturize (re-hydrate) the starch to assist the digestion process.

Flaking Pressure and Moisture Interaction
Secondly they mention the interaction of moisture absorption and flaking pressure or the degree of shear of the pressure of the roller mills on the degree of digestion.

Steaming Time and Moisture
Thirdly they discuss steaming time as a means of adding moisture. Yet they point out that, "longer steaming time may reduce the roll pressure necessary to obtain an optimal shear." They make this observation, "Apparently (from research results) starch digestibility is less dependent on moisture concentration at flaking than on flake density."

The Hard "Horney" Part of the Kernel
Fourth, they mention the problem of the nature of the hard endosperm (the "Horney" dark starch versus the "floury" softer starch area of the kernel.) They imply the enzymes, produced in the digestion process, have difficulty penetrating the starch of the horny part of the kernel. The subsequent moisturizing and flaking process assist the ability of the enzymes to penetrate the starch.

A Protein Barrier Around Starch Granules
Fifth, they address the nature of the protein matrix around the starch granules. As mentioned earlier this is a barrier to the digestion of starch. Here is a quote from their paper:

"Shear (the action of the squeezing of kernel), particularly of the protein-rich horny endosperm, will expose more of the corn protein to the postruminal proteolytic process; this, in turn, increases the exposure of associated starch to the amylolytic precess. Hence, a linkage between postruminal protein and starch digestibility would be expected."

Fiber Digestion in the Colon
And sixth, they point out that fiber digestion may be increased in the cecum and colon. This probably is a minor point in the total improvement of the effect of flaking corn.

For comments or questions to Jim Sprague, 635 Grandview Ave, Newton, Kansas, or call him at 620-283-8692. ©