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Best Crops for Grazing
Grasses are king when it comes to growing cover crops for grazing, says Mary Drewnoski, Extension beef systems specialist at the University of Nebraska-Lincoln (UNL). Both warm- and cool-season cereal grains produce consistent yields of good-quality forage.
On top of that, they accomplish other key goals for planting cover crops. They reduce erosion, build organic matter, and suppress weeds.
Warm-season cereal grains you might choose for grazing are sorghum sudan and pearl millet. Cool-season cereals, of course, include cereal rye, winter wheat, oats, barley, and triticale.
Deciding what species to plant as a cover crop for grazing depends, first, on the planting date, but also on your needs for forage quality and grazing season.
“If you’re planting a cover crop after winter wheat, you could plant as early as July 15 to the first of August,” says Drewnoski. “By planting that early, you could plant a warm-season cereal like sorghum sudan or pearl millet for fall grazing. Or, you could delay planting until after mid-August and plant oats. The yield will be lower for the oats, but because warm-season grains tend to be lower in digestibility, the forage quality of the oats will be higher than that of the sorghum sudan or millet.”
The fall growth produced by cool-season cereals is of higher nutritive quality than their spring growth. “When planted in the fall, these crops don’t lignify as much as they do in the spring,” says Drewnoski.
After a frost, the cool-season cereals like oats and barley wilt and discolor, but the forage retains its quality. “After freeze-up, the cover crop melts down and looks brown and ugly,” she says. “The nutrients and dry matter are still there, though. You can delay grazing until mid-November here in Nebraska.”
The good forage quality of such a cover crop works well for yearlings, but it’s of higher quality than dry cows need, unless they’re limit-fed, says Drewnoski.
In a UNL grazing trial, oats planted as a cover crop on August 20 after alfalfa yielded 3,800 pounds of dry matter (DM) per acre. Oats planted on September 3 after corn harvested for silage yielded 2,800 pounds of DM per acre.
If grazing in fall is your goal, the cereal crops that winter-kill are the best choice for rapid growth and good yields in fall. If spring grazing is your aim, then fall planting the winter-hardy species (like winter wheat, cereal rye, and winter triticale) provides early-, rapid-growing cover crops for spring.
“Cereal rye is the best choice if you’re looking for a grass that comes on early in the spring,” says Drewnoski. “Cereal rye gets going a week to two weeks earlier than other winter-hardy species.” Forage quality of cereal rye declines with maturity.
“By mid-April in Nebraska, you can expect fall-seeded cereal rye to yield 1,000 to 1,500 pounds per acre,” she says. “By mid-May, you can expect yields to climb to 4,000 to 5,000 pounds per acre.”
In another grazing trial, steers grazing rye gained 3.2 pounds per head per day, with a stocking rate of two 700-pound steers per acre. The grazing period extended through the first three weeks of April. Cost of the gain came to 45¢ a pound.
“In my grazing trials, the cost per animal unit month for growing and grazing rye ranges from $16 to $75,” says Drewnoski. “Weather makes the difference in terms of what growing and grazing conditions are like.” (One animal unit month equals one 1,000-pound animal grazing for one month.)
Besides risks posed by weather, timeliness and attention to detail in grazing management present challenges in the grazing of cover crops. “The benefits outweigh the risks, however,” she says.