Follow tips for silage success
High-quality corn silage often is an economical substitute for some of the grain in finishing rations. Corn silage also can be an important winter feed for cow-calf producers. High-quality corn silage takes management and planning to optimize the total digestible nutrients that is harvested.
Harvest timing is critical for success and should be based on moisture content of the silage. Silage chopped too early and wetter than 70 percent moisture can run or seep and often produces a sour, less palatable fermentation. This wet silage is often the product when we rush to salvage hail or wind damaged corn. Seepage is caused by the excessive moisture in the plant when harvested and contains valuable nutrients that are lost. Live and green stalks, leaves, and husks almost always are more than 80 percent moisture so be patient and wait until these tissues start to dry before chopping for silage
Normal corn may be chopped for silage too dry, below 60 percent moisture. Then it’s difficult to pack the silage adequately to force out air. The silage heats, energy and protein digestibility declines, and spoilage increases. If the silage is warm or steams during winter, it was probably too dry when chopped.
Many corn hybrids are at the ideal 60 percent to 70 percent moisture as corn kernels reach the one-half milkline. This guide isn’t perfect for all hybrids, though, so check your own field independently. Corn kernels in silage between half milkline and black layer are more digestible. Drier, more mature corn grain tends to more often pass through the animal without digesting. Also, older leaves and stalks are less digestible. Corn plant moisture varies depending on region, growing season, and hybrid so this technique should be used only as a rough estimate of moisture content. Whenever possible, measure the moisture content with a commercial forage moisture tester or in a microwave oven before harvesting.
To test the moisture content of corn silage with a microwave oven, weigh out exactly 100 grams of fresh silage on a paper plate (don’t forget to adjust for the weight of the paper plate). Spread the forage evenly on the plate and place in a microwave oven. Heat on high for 4 minutes. Remove the silage, weigh and record. Heat the sample again on high for 1 minute. Weigh and record. Be certain to watch the sample during heating as it can become burned and damaged if heated excessively. Repeat this procedure until the weight remains the same. At this point, the weight in grams represents the dry matter content of the silage. To calculate the moisture content, subtract the dry matter content from 100. Example: After several heating cycles, the sample weight stabilizes at 34 grams. Thus, the dry matter is 34 percent and moisture is 66 percent.
Rate of bunker filling
In general, the faster the silo is filled the better. Rapid filling minimizes the risk of feed losses due to inclement weather and advancing maturity of the crop, reduces labor and overall ensiling costs, and improves fermentation by minimizing exposure of the chopped forage to oxygen. Slow filling encourages fungal growth which can result in unstable silage at the time of feed out. When silage is stored in small-diameter silage bags (8 feet), the rate of fill may range from 50 to 200 tons per day. The filling rate of large-diameter silage bags (10 feet), and bunkers silos (1,000-plus tons) can range from 100 tons to 500 tons per day.
Techniques for packing vary depending on the silo type. Upright silos rely on the weight of the silage to supply the packing pressure. Silage bags require special bagging equipment that is adjusted to provide even tension to form a firm tube of silage. Uneven tension results in loosely compacted silage and inefficient use of the silage bag. Correctly packed silage bags look like a sausage and are not lumpy. This lumpiness means the silage is not adequately packed and has more oxygen in the silage than optimal. When ensiling forage in bunker silos, compact it in progressive wedges using a wheel tractor with a front end loader or blade to move and pack silage. This technique minimizes exposure of silage to air before covering. Crawler-type tractors do not provide enough downward compaction pressure and are not recommended. Tractor size should be dictated by the overall needs on the farm and size of the silo.
The amount of time spent compacting and the weight of the tractor used affects silage fermentation. Driving the tractor across the corn silage surface in a bunker many times leads to better fermentation than when the forage is only leveled off with minimal compaction. Ideally, allow 5 minutes packing time per ton of wet forage. Packing excludes oxygen from the silage. Low moisture silage or poor packing allows longer plant respiration and loss of nutrients that cattle could utilize. Good packing and moisture in corn silage also prevents mold growth and leads to a product that is more stable during feed out. Losses can reach 20 percent of the total dry matter harvested. But when density of the corn silage reaches 60 pounds per cubic foot, losses are as low as 10 percent of dry matter.