by Daniel Olson & Larry Hawkins, PAS
The subject of floury corn versus vitreous corn for corn silage has been a controversial one in the past.
However now with some of the detractors breeding floury genetics into their silage corn, there is a greater acceptance and less controversy. Somethings that need to be considered include both yield and cost, as major considerations, but another thing worth remembering is that just saying “floury” is not definitive.
“Flouriness” (to coin a new word!) is a matter of degrees. Your seed sales representative needs to be able to understand his/her hybrids and know how well a particular hybrid expresses its floury trait. Also, some variations of the floury trait like Floury/Leafy have not shown the same advantages as floury corn.
Starting to Understand the Mysteries?
Pat Hoffman now with Vita Plus, but then with UW-Madison, was the man who unsealed the science behind floury corn genetics and prolamin, the low-quality protein that ties up the starch creating vitreous corn hybrids. Also, Dr. Mike Allen of Michigan State University did some important work on floury genetic corn. According to Dr. Allen, there are at least four factors that together govern the availability of the starch in silage and high moisture corn including:
- Dry Matter (DM)
- Particle Size
- Completeness of Fermentation
- Endosperm Type.
The differences because of lower DM levels are real, however, it is always better to have the correct DM for storage than to try to manipulate to gain or decrease starch levels and digestibility.
With vitreous corn, one is almost completely dependent on the combination of smaller particle size (increased grain processing) and the extent of fermentation to get to the goal of higher starch availability. Even with rapid fermentation, this takes four to five months! And longer when the fermentation is not so efficient. A proven preservative is invaluable.
Many dollars have been spent on machinery to reduce particle size in vitreous corn hybrids. However according to MSU research, the small, but still glassy bits of vitreous corn still is washed out of the rumen rather than being held in the rumen mat (see Table 1) to be further digested. This table shows the rate of passage of dry and high moisture (HMC) hybrids is much slower (opportunity for greater digestion) with floury hybrids.
What About Dry Shelled Corn?
With dry shelled corn the differences between floury and vitreous corn are locked in, since no fermentation, the savior of vitreous corn, will occur. More of your grain will be ruminally digested or to look at it another way, less corn (and therefore, more forage) will be needed to be fed to get the same available starch.
Adding Some Numbers to the Idea
The folks at Cumberland Valley Analytical Services (Dr. Ralph Ward) did an interesting study (see Table 1 above) on what changed as fermentation progressed in corn silage. The study represented tens of thousands of samples and looked at all parameters from every sample submitted. The samples were grouped by their submittal dates divided into 3-week periods until no more effects from the fermentation were evident. A few of the parameters are shown in table 1. It is easy to see in this group that DM, CP, NDF, NDFD30 and starch remained the same throughout the fermentation time.
Soluble protein (SP) increases from the proteolysis of fermentation. Sugar went down as the fermentation used some of the sugars.
The obvious reason for this study, In Vitro Starch Digestibility (IVSD 7hr) improved dramatically as the fermentation continued the breakdown of the prolamin.
In the same year, Masters Choice an early grower of floury starch corn submitted 403 plot samples of their hybrids to CVAS (see Table 2). These samples were in early fermentation (approximately 1½ months). These samples were not in a perfect environment for fermentation (such as the middle of a bunk silo but were in sample bags. We did not have further samples to test to see if they improved more after this initial fermentation, however, they were already better than the CVAS data set was after 5 months. Even if they did not get much better than the Table 2 shows, they still were better already!
The Bottom Line
Floury starch hybrids can add efficiency to your corn silage and corn grain feeding:
- You will not have to wait so long to feed silage after harvest.
- You will not need 5 extra months of storage. In most cases, you will be feeding less total corn (including the corn in your silage plus the corn grain or HMC) due to its year-around higher starch availability.
- Even if the difference is only a small amount of IVSD 7 toward of the bunk, there is still a difference and the vitreous particles even though further processed, will pass out of the rumen undigested.
- Processing can be reduced saving horsepower at harvest.
If you would like to visit more about forage options reach out to schedule a virtual meeting! We would be glad to help start the planning process for 2022. This early fall provides some great opportunities for a successful 2022. Our seed company partners have some great pricing and quality varieties still available for this fall.