September, 2003

by Daniel R. Moser
Research Nebraska September 2003

Summer can offer slim pickings for hungry beef cattle in eastern Nebraska, as the smooth bromegrass that dominates the pastures they graze wears thin. University of Nebraska researchers are exploring ways to diversify those pastures to provide more nutritious, reliable fare through the summer.

Researchers are seeking the right mix of vegetation to supplement bromegrass and the best grazing system to take full advantage of pastures throughout the season. Smooth brome, which has become dominant in eastern Nebraska pastures over the past 100 years, provides plentiful, high quality forage during the critical spring calving season and often again in the fall. But it suffers a “summer slump in quantity and quality,” said Range Scientist Walter Schacht. That leads to a decline in cattle performance.

Institute of Agriculture and Natural Resources research focused on interseeding three legumes — alfalfa, birdsfoot trefoil and kura clover — into the bromegrass in NU test pastures. Researchers compared cattle performance on these interseeded pastures with performance on regular pasture. Results were encouraging, said Forage Scientist Bruce Anderson.

“The legumes managed to boost productivity, feed availability and the quality of the grazing forage in those pastures” from July through September, Anderson said. Legumes helped improve beef gains by 25 to 40 pounds per acre. “We figure 45-50 cents additional net income for each extra pound,” Anderson said. “While that isn’t earthshattering, we’re still talking about $10 to $20 an acre of additional income.”

Unlike brome, legumes don’t require fertilizing once they are established, which cuts costs. Unfortunately, it’s difficult to plant and establish legumes in existing bromegrass. Research is continuing to improve the effectiveness of interseeding. Meantime, researchers are finding promise in using native warm-season grasses such as indiangrass, big bluestem and switchgrass to complement bromegrass.

One key: finding a grazing system that makes the best possible use of both cool- and warm-season grasses. “Historically, we’ve promoted a simple grazing system that says graze the cool-season grass in spring, the warmseason grass in the summer and back to the cool-season grass in the fall,” Anderson said.

Research has found, though, that it’s better for the pastureland and, ultimately, the cattle, to use a rotational approach that gives grasses time to recover from the grazing.

NU researchers developed an early-season grazing strategy for warm-season tallgrasses that improves the efficiency of their use through the growing season. Cattle begin spring grazing bromegrass and move in midto late May to briefly graze the warm-season grasses that are just greening up. Then it’s back to the smooth brome for several weeks, finishing the spring growth of the brome and allowing the warm-season grasses to regrow so they can provide feed for the rest of the summer. Then it’s back to brome in the fall.

Early grazing on warm-season grasses helps slow their rapid growth and make them leafier and more nutritious later.

Also, scientists  are developing improved range grass varieties. Ken Vogel, a USDA-Agricultural Research Service geneticist in UNL’s Department of Agronomy and Horticulture, has developed a couple of big bluestem varieties that show signs of improving animals’ performance during summer. A new switchgrass variety — Trailblazer — has proved more digestible than earlier varieties.

This NU research already is paying dividends. Anderson and others documented about a $7 million economic benefit among 1,600 graziers who participated in a series of NU Cooperative Extension workshops based on IANR research. Those producers manage about 700,000 acres and 142,000 cattle.

“This is basic fine tuning that can be achieved through good management and a minimum amount of high-cost inputs,” Schacht said.

The NU Foundation’s Sampson Endowment helps fund this research.