Cattle and sheep together: partners in grazing.
"Cattle, sheep, and even goats complement one another on rangeland," says range animal scientist Dean M. Anderson, based at the ARS Range Management Research Unit at Las Cruces, New Mexico.
"Not only have we found the three species make better use of rangeland because they eat different plants. We also discovered that if sheep and goats learn at an early age to stay with cattle, the cattle's presence protects the smaller animals from coyote predation."
Sheep and cattle grazing together normally don't associate with each other. But if the two animal species are introduced soon after the lambs are weaned, that behavior changes.
"Then, lambs form a close social bond and develop an impelling need to be close to cattle as they move about on the open range," says animal physiologist Clarence V. Hulet, recently retired from the Las Cruces lab.
The ARS scientists found that enduring social bonds were formed when 45- to 90-day-old lambs were penned with docile yearling heifers for 30 to 60 days. The two species then freely intermingled as they roamed pastures and on the agency's 193,000-acre Jornada Experimental Range near Las Cruces.
Hulet and Anderson point out that coexistence is nothing new in the animal kingdom. Various animals have shared feed in the same area for centuries. For example, this type of grazing still exists today on the natural grassland ecosystem of the Serengeti in Tanzania and Kenya in east Africa among wildlife such as gazelles and zebras.
The ARS behavior-oriented grazing research adds a new twist to studies begun in the 1920's by the Texas A&M University Research Station at Sonora, Texas. In the 1950's and 1960's, studies of cattle, sheep, goats - and later deer - showed all the species do well together on shared range.
The scientists at Las Cruces have confirmed the dietary differences of these livestock - that cattle eat mainly grasses, while sheep and goats prefer broadleaf plants such as forbs and leaves from some small shrubs.
The Jornada research team is now studying a shrub called tarbush, one of four woody plant species ranchers had previously wanted to eliminate completely from their ranges to make room for forage grasses.
"Our current research is aimed at understanding why some plants are palatable to livestock while others are ignored," says Kris M. Havstad, research leader and range scientist.
He and fellow researchers found livestock would eat up to 99 percent of newly formed leaves on some tarbush plants, while leaving other tarbush plants untouched.
This variability suggests some element in the plant attracts or repels grazing animals. The researchers think plants have specific chemical signatures that are recognized by an animal and directly affect palatability. They have begun detailed analyses of tarbush plant components.
"If we can determine how to safely increase the use of previously unused woody species, including honey mesquite, creosotebush, and broom snakeweed, we could tap an unused range resource," says Havstad. "Livestock grazing can be a tool to restore biological diversity without harmful environmental effects.
"It may be possible to condition young animals to include these plants in their diets, in much the same way we condition sheep and cattle to graze together."
A similar study in Idaho's upper Snake River plain also points up the potential benefits of multispecies grazing.
There, sheep nibble on forbs like arrow leaf balsam root, which sports bright yellow flowers, and the purple-blossomed hawksbeard. Meanwhile, cattle on the same pastures feast on bunch grasses such as the bluebunch wheatgrass and speargrass.
"Cattle alone tend to graze grasses," says John W. Walker a range scientist with the ARS Range Sheep Production Efficiency Research Unit in Dubois, Idaho. "But turning out a combination of animals to graze together helps preserve the area's natural diversity. If you put out just cattle that tend to prefer grass, the grass gets grazed year after year, and that hurts its ability to compete with the other plant species, reproduce, and maintain itself in the plant community."
"With multi-species grazing, you evenly defoliate the forage species in the area, and their ability to compete for water and nutrients is more nearly equal," he says.
Early results from field studies suggest that lambs especially benefit from such an arrangement, since they gain slightly more weight when grazing with cattle than when grazing with sheep alone. Researchers think that's because there is less competition for the lambs' preferred plant species.
In California's Sierra Nevada mountains, researchers have focused on harmoniously blending livestock with nature.
They are studying a meadow that adjoins Big Grizzly Creek in the Plumas National Forest on the California-Nevada border, not far from Reno and Lake Tahoe, the site of a 4-year study. Here, Nebraska sedge, tufted hairgrass, and baltic rush cover the floors of high mountain meadows, providing sustenance for the cattle that graze the meadows periodically throughout the summer.
It's an ideal setting to measure the cycling of water and nutrients in mountain meadows and streams and to see how cattle grazing influences these cycles.
Of special interest in this study is the riparian zone, the span of lush, green vegetation alongside streams and other waterways.
"Riparian zones are important for lots of reasons - water quality and quantity, forage production, and wildlife habitat," says Gregg M. Riegel, a range scientist with the ARS Landscape Ecology of Rangelands Research unit in Reno, Nevada.
The ARS project, which began in the spring of 1989, calls for extensive studies of the meadow's soil, water, and plants. The researchers are looking at how these are affected when a meadow is lightly grazed, moderately grazed, or left ungrazed.
When cattle graze, they consume nutrients like nitrogen and phosphorus that are stored in the plants. The animals' bodies convert these nutrients to muscle tissue - the steak or hamburger that ends up in supermarkets.
The scientists are measuring soil nutrients, plant growth, and water table changes near the stream, in the middle of the meadow, and near the edge of the forest.
"We feel that a better understanding of how these ecosystems work will help in future resource management decisions," says range scientist Tony J. Svejcar, one of the project's initiators. Formerly at the Reno research station, he is now research leader at the ARS Range and Meadow Forage Management Research Unit in Burns, Oregon.
The early data hasn't shown any striking differences among any of the different grazing treatments. But the scientists have analyzed only a year's data thus far.
"One interesting finding was that the meadow contained a clay mineral called smectite," says Robert R. Blank, a soil scientist with the Reno lab.
"The mountain meadow isn't a typical environment for smectite to form in. A more arid setting would be more usual - an environment with a strong seasonal dry period and a more alkaline soil."
Because it sloughs easily, smectite may be more sensitive to the hooves of trampling cattle near the stream, he notes.
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|Author:||Senft, Dennis; Corliss, Julie|
|Date:||Dec 1, 1991|
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