by: Heather Smith Thomas
Some forage species are more energy-dense than others. Beef producers around the world have been utilizing some of these species in grass-fed beef production, using forages instead of grain for finishing beef animals. Some of these forages can also be beneficial in a fall/winter grazing program.
Mary Beth Hall (Research Animal Scientist) and Geoffrey Brink (Research Agronomist) at the USDA-Agricultural Research Service, U.S. Dairy Forage Research Center in Madison, Wisconsin, both work with forages and nutrient needs of livestock. “When we talk about energy-dense, we mean a forage that is more digestible, delivering more nutrients to the animal during a day's worth of feed or grazing,” explains Hall.
“There are some feeds that are very high in energy, with a lot of non-fiber carbohydrates and the fiber is very digestible, but if there isn't sufficient quality, you still won't meet the animals' needs. So we have to find a balance,” she says.
On the other hand, there are plants that have a high level of structural carbohydrates but are not as palatable. “You need plants of high enough quality and quantity that the animals will eat enough of it. This goes beyond plant composition; it also includes how you manage the pastures,” she says.
There are a number of forage species that fit nicely into a forage beef production program, supplying adequate nutrition for growing animals or even finishing animals. Brink says that in the South, the most popular option is overseeding a warm season grass with some kind of annual grass such as annual ryegrass.
“Annual grass is a very high-quality, low-fiber, highly digestible grass that is oversown on Bermudagrass and other warm season grasses. In our cooler climates, however, we rely on temperate or cool season grasses that are perennial rather than annual, even though there are some annual options. Wayne Coblentz, another one of the Center's scientists has investigated oats planted in late summer to provide fall grazing. This gives a very high NSC feed from early September until the snow falls, depending on when it is planted,” Brinks says. This could fill the gap in late fall when other grasses have dropped in nutrient quality and productivity.
“Stockpiled tall fescue is also good fall feed for beef cattle if it is adequately fertilized. The new endophyte-free varieties are a better option for stockpiling than the typical endophyte-infected Kentucky 31,” says Brink.
“For spring grazing options, some grazers plant a mixture of turnips and wheat in the fall, and this will provide some fall and early spring grazing. This is a fairly high quality mixture compared to most other forages,” he says.
Hall says most stockmen try to have a variety of forages, to provide high quality feed at various times of the year, with no gaps. “It depends entirely on the growing season, however. There is no such thing as a foolproof crop. It's a matter of looking at the options that work in your own climate, for filling in the gaps, and selecting something that is suited for your area,” she says.
Brink points out that legumes are another type of energy-dense forages. “Many people include legumes in a pasture mix, particularly in perennial pastures. Some will overseed perennial or even annual legumes. In the south, annual legumes such as crimson clover are often used. In a temperate climate, red and white clover and alfalfa are utilized, which are all perennial legumes. Legumes improve the digestibility and energy content of perennial pasture significantly,” he says.
“There are some regions where forages like perennial ryegrass will work. In terms of cool season grasses, perennial ryegrass is one of the highest energy grasses available. These are the types that are utilized in New Zealand and Ireland/Great Britain. These perennial ryegrasses will often have a fiber content 5 to 10 percent lower than typical cool season perennial grasses,” Brink says.
Hall says the growing conditions in New Zealand and Ireland are ideal for these ryegrasses. “They have the moisture, sunlight, and cooler temperatures—without the extreme cycles in temperature that we have,” she says. In northern climates we must be selective in the forages we choose, so they won't die out over winter.
“Here in Wisconsin, perennial ryegrass is often sown when a producer establishes a new pasture, as a means of increasing the yield during the first growing season,” says Brink. “Producers realize that within a couple years the amount of ryegrass in that pasture may be significantly less than the first year. It often doesn't have the cold tolerance we need, nor the summer drought tolerance,” he says. Producers often add it to the new seeding, however, because it establishes so rapidly the first year, and gives cattle excellent forage while the other plants are growing.
“This brings up the importance of how you manage the land and the grazing,” says Hall. “What you do in terms of fertilization and grazing management may help ensure more chance for getting the feed you want for your animals,” she says.
“It is important for beef producers to understand the nutrient needs of growing animal because sometimes they are shortchanged in terms of pasture management. A pasture grazed at a more vegetative stage (young and growing versus mature) will provide more energy—just because the fiber level of the plant is lower than in a more mature grass. While a growing beef animal will consume a more mature grass, the quality may not be high enough to produce much weight gain,” he says.
Hall says it all boils down to how much the animal can consume of the given forage. “If it is too mature, there is a limit to how much they can eat, simply because the material will fill up the rumen (and doesn't break down as quickly during digestion) and the animal can't eat any more,” she says.
“So we have to look at how much they can eat, and then we have to factor in the composition of the forage to know whether they get the pounds of digestible nutrients and protein they need, to support the performance desired,” says Hall.
Don't forget to
Cattle Today Online!