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High Moisture Corn Strategies
by Mike Hutjens, Extension Dairy Specialist, University of Illinois, Urbana

As Illinois dairy farmers continue to chop corn silage, harvesting high moisture corn is just around the corner. A hot July and dry August have pushed corn to an early maturity. A 1998 U.S. survey reported 44 percent of responding dairy farms were feeding high moisture corn; 77 percent as shelled corn and 23 percent as ear corn. Iowa researchers report lower field losses (5 to 12 bushels of corn) when grain was harvested as high moisture corn compared to dry corn. Several points concerning high moisture corn should be considered.

Moisture Levels of the Grain

Penn State University workers recommend the following moisture levels and outside ranges for high moisture corn. High moisture shelled corn: 25 to 30 percent moisture (range of 25 to 35 percent)High moisture ear corn: 30 to 35 percent moisture (range of 28 to 40 percent) Table 1 compares typical moisture content of the kernel, cob, and whole ear at various stages. Weather conditions, plant maturity, and corn varieties can impact these values. Test kernel or whole ear for dry matter content with a moisture tester. If corn is too dry, poor fermentation and storage losses occur. If corn is too wet, it can lead to rumen digestive disorders and lower feed value. Snaplage as an Alternative With the availability of plant processors (also called kernel processors), snaplage is another way to harvest the wet corn grain. Snaplage consists of the ear, husk, and some up plant parts. In the 1970s snaplage was not popular due to separation in the silos, lower energy content, slow harvesting, and mold formation in silos. With high capacity field harvesters with a snapping head, large quantities of snaplage can be harvested and processed in the field. Cob and kernel particle size can be adjusted by changing theoretical length of chop (TLC) and distance between the rollers (1 to 4 millimeters). Snaplage will lower in energy value than ear or shelled corn, but yield is higher containing more fiber and less starch. Storing snaplage in bags or bunkers reduces separation problems. Harvesting at 40 percent moisture can result in quality feed with little storage problems. Be sure to adjust the amount of snaplage fed based on dry matter content and lower energy content. Adding several pounds of finely ground shelled dry corn can increase starch content in the total ration if needed.

Energy Value of Wet Corn

U.S.D.A. researchers reported that high moisture corn had more energy than dry corn (Table 2). Moisture content and processing of the high moisture corn is critical to obtain the added energy value. If high moisture corn is below 25 percent moisture, it can have energy values similar to dry corn and require more processing to reduce particle size for optimal rumen fermentation. Wetter high moisture corn needs to be processed coarser to avoid rumen digestive disorders.

Bagging High Moisture Corn

Excellent quality feed can be stored in a bag IF it can be maintained in a sealed unit. Rodents, raccoons, and birds can cause damage and expose it to air; bags must be protected. When ensiling in a bag, harvest high moisture corn at the wetter end of the moisture ranges listed above. Corn should be processed prior to bagging to exclude oxygen and stimulate fermentation. An effective (based on research results) inoculant for high moisture corn is recommended. Table 3 lists storage capacities of various bag sizes and lengths.Variation in High Moisture Corn One disadvantage of high moisture corn is its variability. Dry matter content can change, grain particle size can shift due to moisture and variety differences, kernel hardness can vary, and secondary heating and molding in storage can be a problem in the late fall (immediately after ensiling) and during the summer. Herd sizes must match recommended feeding rates (4 to 6 inches off of the face or surface in the summer and 2 to 3 inches during the winter). One key to a successful feeding program is a consistent high quality ration day in and day out. Be sure your high moisture corn meets this requirement.

Table 1. Kernel, cob, and ear moisture relationships (Source: Penn State Circular 143).

  --------------- % moisture ---------------
Kernel 20 26 30 34 38
Cob 33 47 52 56 58
Whole Ear 23 31 35 39 43

Table 2. Comparison of rolled and ground dry and high moisture corn (Source: Glenn, U.S.D.A.).

  Dry Corn High Moisture Corn
  Rolled Ground Rolled Ground
Dry Matter intake (lb/day) 45.5 50.4 47.9 53.7
Milk Yield ( 74.8 77.4 77.4 77.4
Starch digestibility-rumen (%) 69.2 60.9 81.2 86.8
Calculated NE-lact (Mcal/lb DM) 0.75 0.74 0.78 0.83

Table 3. Bag storage capacity for various bag sizes and types of high moisture corn (Source: Total Agri-Business Service August newsletter)

Bag Size in feet (diameter x length) Ground Corn Ground ear corn
  -----------tons as fed basis-------
8 x 100 87 56
8 x 200 190 120
9 x 100 114 73
9 x 200 235 148
10 x 100 135 83
10 x 200 270 165
12 x 100 125 110
12 x 200 355 215

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