A forage harvester chops lime-treated corn-stover windrows.
Lime-treated corn stover can reduce feed costs when substituted for corn silage and/or corn grain in livestock rations. But producers need to plan the treatment carefully to make sure it’s done safely and effectively.
So said Dave Combs, University of Wisconsin dairy scientist, who treated and fed stover in a research trial and discussed the topic at the recent Midwest Forage Association, Wisconsin Custom Operators and Professional Nutrient Applicators Conference.
At a cost of $20-30/ton, he said lime treatment can substantially improve stover’s digestibility, increasing its energy content. The treatment involves chopping stover to 3-6” particle lengths, adding calcium oxide or calcium hydroxide at 5% of the stover’s dry weight, adding water to bring the dry-matter content down to 50% and storing the mixture for five to seven days.
Calcium oxide, also called quicklime, is used most often. It converts to calcium hydroxide when water is added, but that can cause a violent reaction if not done carefully. Also, quicklime dust reacts with perspiration, causing irritation and burns. If inhaled, it may burn the respiratory tract, and eye tissues may be damaged if the dust gets behind contact lenses.
“You haveto be very, very careful if you’re going to use this material,” Combs cautioned. “Most people are moving toward a slurry and making a wet material to avoid the dust.”
Dry hydrated lime is less caustic and easier to work with, he said.
When dry baled stover is treated, significant amounts of water are needed to create the 50%-dry-matter finished product. In Combs’ research, a tub grinder was used to process bales that averaged 1,055 lbs and were 90% dry matter. More than 100 gallons of water were added to each bale, along with 50 lbs of lime. If 50 tons were treated, more than 10,000 gallons of water would be needed, he pointed out.
“You aren’t going to do that with a small water hose,” he said.
Less water is needed when stover is windrowed shortly after the grain harvest, treated in the field and chopped by a forage harvester. If harvested shortly after high-moisture corn is combined, the stover may already be 50% dry matter.
“Getting enough water on this material is one of the real challenges,” said Combs. “So if it can be done immediately behind the combine, you can save yourself a tremendous amount of water.”
One treatment method is to drop dry lime onto the windrows using a fertilizer spreader, then follow with a water tank if water is needed.
Treated stover is typically stored in a bunker or silage bag. If put in a bunker, it should be packed to exclude oxygen, and with either storage method it probably will begin to ferment. But it’s the chemical reaction, not fermentation, that improves digestibility, Combs noted.
Lime treatment breaks up bonding in the stover’s cell walls, making the fiber more accessible to rumen microbes, increasing digestibility. Research at Iowa State University and the University of Nebraska revealed that treated stover can substitute for some of the corn grain in beef cattle rations.
Iowa State workers found that a 2:1 ratio of distillers grains and treated stover can replace up to half the ground corn in feedlot diets. In Nebraska, lime-treated stover replaced 10-15 percentage units of corn in backgrounding and finishing diets without affecting dry matter intake, daily gains or feed efficiency.
“So it looks very, very promising on the beef-cattle side,” said Combs.
In a Purdue University study with dairy cows, milk production held at 65 lbs/cow/day when treated stover replaced a portion of the ration corn silage. But dry matter intake and milk production dropped in a recent Wisconsin study evaluating treated stover as a corn grain replacement for cows producing about 100 lbs of milk/day.
While treated stover looks less promising for dairy cattle, Combs thinks it may work for lower-producing cows or heifers, especially if it replaces corn silage.
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