By Russ Quinn
DTN Staff Reporter
MEAD, Neb. (DTN) -- Corn silage can be an economical feedstuff for beef cattle operations, especially in times of drought. But those who utilize the feedstuff have a laundry list of items they need to consider in order to maximize their investment. Silage management entails both how the crop is chopped in the field and how it's stored on the farm.
The topic of corn silage management was discussed at the Silage for Beef Cattle 2018 Conference held June 15 at the Eastern Nebraska Research and Extension Center located near Mead. The daylong conference was sponsored by University of Nebraska-Lincoln (UNL) Extension, Iowa State University Extension and Outreach and Lallemand Animal Nutrition.
HARVESTING KEYS
Whole-plant corn silage is a predominant forage used all over the world for dairy cattle diets, according to Luiz Ferraretto, assistant professor of livestock nutrition at the University of Florida and a presenter at the silage conference. Beef cattle producers are increasing the amount of silage they use, as well.
One way to increase the value of silage is to use a kernel processor on the forage harvester. Kernel processors crack the corn kernels during harvest, thus improving kernel digestibility, especially when kernels are mature, he said.
Ferraretto said the degree of kernel processing may be inhibited by other factors, such as the length of the cut setting. Processing has been shown to increase the total tract starch digestibility when the length of the cut is set at 0.37 inch to 1.13 inches but not if it is set shorter or longer.
"This is likely related to greater kernel breakage during passage through the rollers by the stover portion at the longer theoretical length of cut," Ferraretto said.
Utilizing a kernel processor may be especially useful if corn silage harvest is delayed. Dry matter levels of harvested silage could be increased if a processor is used, as the endosperm of the kernels is broken down more, he said.
Another harvesting management factor that silage harvesters should keep in mind is chop height.
Ferraretto said lignin is an important structural component of corn that is concentrated in the bottom part of the corn plant. Lignin is an organic polymer deposited in the cell walls of many plants that makes them rigid and woody. Chopping silage at a higher level leaves more lignin in the portion of the plant that stays in the field, and thus digestibility of the harvested material is greater.
Studies at the University of Florida compared 6-inch and 24-inch cutting heights. The results showed that dry matter yields were reduced as the chopper head was raised. However, decreased dry matter yields were offset by an increase in the milk-per-ton estimates for dairy cattle fed silage produced by the higher chop height, he said. The greater milk estimate is the dairy cow's response to the greater fiber digestibility and starch concentration of the harvested material.
Producers should discuss farm priorities for maximum yield versus higher quality with nutritionists and crop consultants, Ferraretto said.
"Those needs may vary in different years depending upon the yield and the quality of the crop and existing on-farm inventories," he said.
ENSILING CORRECTLY
The other half of silage management is ensiling the feed correctly. Silage is a product formed when forage with adequate moisture content is stored anaerobically (without oxygen), Renato Schmidt, technical services - forage for Lallemand Animal Nutrition, said during his presentation.
Two goals of the ensiling process are to retain as much of the original nutrients and dry matter as possible through efficient lactic acid fermentation and to have a stable product throughout the phases of storage and feed-out, he said. Losses inevitably occur during field harvest, the ensiling process, microbial fermentation and exposure to air during storage and feed-out.
"Air (oxygen) is the worst enemy of silage," Schmidt said. "Packing the forage tight is one of the most important and most overlooked factors when making good silage."
Schmidt said the basics of ensiling should include spreading thin layers (6 inches thick) of fresh forage on the pile, packing silage continuously and packing with heavy tractors.
The "800 rule" is a practical and easy tool to remember, as 800 pounds of packing weight is needed for every ton of crop delivered per hour, he said. For example, for a delivery rate of 150 tons per hour, 120,000 pounds of packing weight (tractors) would be required for the proper packing job, he said.
After the silage is packed, it is imperative to properly cover and seal the silage as soon as possible, Schmidt said. Studies have shown that uncovered silage has extensive losses due to air exposure and the effects of the elements, he said.
Horizontal silos usually have been covered with a polyethylene sheeting and weighted down with old tires, ideally split in half to reduce the weight and eliminate breeding grounds for mosquitos. White plastic is better than black sheeting, he said.
"A more recent technology to cover the silo is with two layers of sheeting," he said.
One layer would be an oxygen barrier film, which would be made of polyamide and would be less permeable to oxygen transfusion, he said. The other sheet would be regular polyethylene to protect the polyamide against mechanical damage.
Schmidt said feed-out removal rates of silage from the silo also affect the quality of the feed. Fast removal can lead to reduced aerobic spoilage and limit losses. Schmidt recommended 4 to 6 inches of silage per day be removed from the pile face.
Using a mechanical defacer or rake helps to reduce aerobic face losses, as it minimizes the air penetration, he said. Using a bucket to knock down silage creates larger fractures in the silo face, which allows oxygen to penetrate deeper, causing heating and greater feed-value losses.
LOSSES ADD UP
Schmidt said better packing and feeding-out of silage leads to less dry matter and nutrient losses.
Common dry matter losses, or shrink, are usually found in the 15% to 20% range. If shrink could be by reduced by 5%, there could be a savings of $2,000 per 1,000 pounds of silage, assuming that the silage is valued at $40 per ton, he said.
Paying attention to the details in all aspects of ensiling are important to retain nutrients and dry matter, he said.
Feed preservation is important when putting up and feeding silage, said Andy Skidmore, technical services - ruminant for Lallemand Animal Nutrition. Spoiled silage has an effect on the cattle eating the damaged feed, he said.
Skidmore cited a Kansas State University study in which steers were fed varying proportions of spoiled and normal corn silage. A higher percentage of spoiled silage fed to the steers decreased crude protein digestibility and had a large negative effect on dry matter intake.
"When the ruminal contents were evacuated, the spoiled silage had partially or totally destroyed the integrity of the forage mat in the rumen," Skidmore said.
Skidmore said silage can be contaminated from various sources, including soils, plant decay from pests or hail, manure, decaying animal carcasses and mold. Cattle that eat contaminated silage could develop diseases such as salmonellosis, listeriosis, botulism, cryptosporidiosis and overall general poor performance, he said.
Russ Quinn can be reached at russ.quinn@dtn.com
Follow him on Twitter @RussQuinnDTN
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