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It is the time of year when farm discussions focus on corn silage harvest. As I visited farms this past week, it was apparent corn silage harvest would begin soon in some areas where others are hopefully a few weeks away. Corn on sandy ground and planted in early May is drying down fast in the dry August weather. Other areas with late-planted corn are going to need a few more weeks of warm weather for full grain development. However, these fields will dry fast too with 90-degree temperatures and strong southerly winds.
Corn for silage is harvested every year, so the process is a standard routine. However, it seems every year some glitch occurs in the process and a lot of corn silage is not optimally harvested. Some of the things that go wrong are it doesn't get chopped and processed properly, the corn is either too wet or too dry at harvest or upon opening the silo we find out it didn't ferment well and there is mold/yeast in the silage. Therefore, with this in mind, here is a quick checklist of good corn silage harvesting practices.
• Chopper in good working order and set to go: The chopper knives should be sharp and there should be proper clearance between the knives and shear bar. This will help avoid the shredding of corn silage and allow for a uniform chop. Recommended theoretical length of chop (TLC) for corn silage is 3/8 inches (9 to 10 mm) for unprocessed and 3/4 inches (19 mm) with a processor. Evaluate the processing rollers for wear. The grooves should be clearly visible with sharp edges. Suggested roller gap to start harvesting is about 3 mm.
• Do not forget about the silage wagons and tires. Check them over before starting to harvest. It is quicker and easier to replace a worn out tire on an empty wagon than a fully loaded one during harvest.
• I am sure we are going to see a lot more shredlage corn silage this year. Initial research last year looked very promising and the longer fiber (1 inch or 26 mm chop length) may be particularly appealing as corn silage replaces alfalfa in diets. Shredlage appears to be a very good way of harvesting corn silage, but shredlage only makes good corn silage better, not bad corn silage good. The silage will have to be harvested at the right DM and stored correctly to gain the advantages shredlage has to offer.
• Has your inoculant been ordered and the equipment to apply it tested and calibrated?
• Harvest plants at the correct DM: Corn silage should be harvested at 33 to 37 percent DM (67 to 63 percent moisture). Crop development needs close monitoring this year, as there will likely be crops at different stages of maturity at the time of harvest. Visual appearance of the plant will not suffice as the indicator of when to start chopping and whole plant DM is 35 percent. Chopping some stalks and drying them down is the best way to get the DM of the silage right at harvest. Corn can dry down fast this time of year, so monitor the crop drying process closely.
• Once chopping has started, check the particle length of the corn silage using the Penn State Particle Separator. General recommendation is 5 to 15 percent of the particle sample size by weight on the top screen. Wisconsin particle sizing of shredlage shows the top screen can be over 30 percent. The middle box should contain greater than 50 percent of the particle-sized sample (by weight). The middle screen also is a very good place to inspect effectiveness of kernel processing. The bottom pan should have minimal material in it, generally less than 10 percent. Baggers and silo unloaders can decrease corn silage particle, so be sure to factor this in to the chop length of the silage going into storage.
• If you are using a processor, it is good to check if the silage is being adequately processed. Dr. Bill Mahanna recommends filling a 32-ounce cup with a representative sample of chopped corn from the field. Spread the material on a flat surface and pick out the half or whole kernels. If the processor is working correctly, there should be less than two kernels (halved or whole) picked out. This test may work also for shredlage, as you do not want whole kernels in shredlage either.
• Filling the silo: Rapid filling, tight packing, and proper sealing are essential in order to exclude air from the silage mass. These three important tasks represent the last management opportunity to establish a good ensiling process and have high quality silage coming out of the silo. In general, the faster any silo (upright, bag, bunker or pile) is filled the better. Slow filling encourages mold and yeast growth, which can result in unstable silage at feed out. Cover bunkers and piles with a heavy polyethylene plastic and preferably use an oxygen-limiting barrier to aid in reducing spoilage and DM loss.
• Mold, mycotoxins and yeast in the silage all originate in the field and plants pre-harvest. Environmental conditions such as excessive moisture, temperature extremes, humidity, drought and physical damage to the plant from insect or hail all predispose the plants in the field and determine the severity of contamination. Molds also originate from soil contamination on the plant pre-harvest or during the time of harvest. Preventing proliferation of these organisms during storage through good silage management practices is essential for high quality low mold and yeast silage.
Feeding high corn silage diets: For many producers, corn silage will be the major forage in the diet this fall. Do some ration planning to get a good estimate of the quantity needed for this next year. Build corn silage inventory as this will be the lowest cost forage source this year and a good hedge against an unknown 2014 growing year.
Here are a couple of ration items to watch for when feeding high corn silage diets.
• Watch starch levels in the diet (23 - 28 percent guideline). If the silage has a good starch level and the kernels have been processed correctly, very little additional corn grain will be needed in the diet. Dry corn will be a better fit with high corn silage feeding than high moisture corn.
• Monitor effective fiber in the diet through cud chewing, fat test and manure scores. If the chop length of the silage is short, some effective fiber such as straw or coarse chopped good quality hay should be added to the TMR. Fuzzy cottonseed may also provide some effective fiber.
• The ration forage NDF level should be 21 percent or higher with total NDF above 30 percent.
• Buffers are essential in high corn silage rations. Research shows the response in milk and milk fat will more than pay for feeding.
• Both rumen degradable protein and undegradable protein are needed in the ration. Good corn silage will support high levels of rumen bacterial protein production with adequate degradable protein (9 to 10 percent of the DM) in the ration. Balancing for lysine and methioine with undegradable protein sources (6 to 7 percent of the ration DM) is needed to supplement bacterial protein for good milk production and milk components.
• Use high fiber, low starch byproduct feeds when corn grain and corn silage amounts have maxed out. Soyhulls, corn gluten feed and fuzzy cottonseed are good sources of NDF and available this year. They add nutrients to the ration without adding starch.
• To top off the energy in high corn silage rations, use a dry bypass fat. Tallow and liquid fats may reduce milk fat test and possibly lower intakes when added into high corn silage rations. Use of high fat distillers grains should be limited for this reason also.
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