WOLFY FORAGE: ITS EFFECT ON CATTLE DISTRIBUTION AND DIET QUALITY

Authors: Ganskopp, David; BOHNERT, DAVID - OREGON STATE UNIV

Submitted to: Eastern Oregon Agricultural Research Center
Publication Type: Experiment Station
Publication Acceptance Date: 2/20/2004
Publication Date: 6/29/2004
Citation: Ganskopp, D.C., Bohnert, D. 2004. Wolfy forage: its effect on cattle distribution and diet quality. Eastern Oregon Agricultural Research Center. Range Field Day Report 2004: Current Forage and Livestock Production Research. Special Report 1052. P. 4-9.

Interpretive Summary: Bluebunch wheatgrass and crested wheatgrass, 2 of our major rangeland grasses in the western United States, accumulate large amounts of persistent stems and become what are known as 'wolf' plants. Cattle are reluctant to use wolf plants because of the physical barrier of the old, cured stems and the reduced nutritional value of aged materials. This study evaluated the effects that stands of wolfy plants have on the distribution of beef cattle in pastures and the nutritional plane of beef cattle confined to either wolfy or uncontaminated sections of forage. When grazing, cattle exhibited a 2.7 to 1 preference for non-wolfy portions of pastures even though they contained less than half as much forage. Over a 7-day trial cattle used about 13 percent of the grass in uncontaminated sections of pastures and additional herbage grew in wolfy sections Diet quality of cattle was the same, however, when cattle were confined to either wolfy or uncontaminated portions of pastures. If forced, cattle can at least initially sort high-quality herbage from wolfy plants. These findings suggest that cattle distribution patterns in pastures are self sustaining. Cattle will likely graze all herbage in pastures if wolfy sectors are cleaned up with heavy late-season grazing, mowing, or burning to remove standing dead materials.

Technical Abstract: Other research has shown that cattle are cognizant of even 1 cured stem in clumps of green grass, and they are about 40 percent more likely to reject a wolfy plant than plants not contaminated with cured stems. No research, however, has examined cattle responses to stands of wolfy forage at landscape levels or their diet quality when confined to either wolfy or clean stands of grass. GPS collars were used to ascertain cattle distribution in pastures where half the area was wolfy and half supported uncontaminated growth. When grazing, cattle exhibited a 2.7 to 1 preference for uncontaminated sectors of pastures even though they supported less than half as much forage. Over a 7-day trial, standing crop declined by 13 percent in uncontaminated sectors and increased by 10 percent in wolfy areas. Cattle traveled more each day as the trial progressed (2.3 miles at the beginning and 2.9 miles at the end) a possible response to dwindling forage supplies. Crude protein (11%) and digestibility (58%) were the same for cattle diets in wolfy or uncontaminated portions of pastures suggesting cattle can effectively select a high quality diet from among wolfy herbage. Cattle will more likely consume all herbage in pastures if wolfy sectors are cleared of older materials with heavy, late-season grazing, mowing, or burning.