Livestock forage conditioning among six northern Great Basin grasses

Abstract

Studies of Anderson and Scherzinger's forage conditioning hypothesis have generated varied results. Our objectives were (1) to evaluate late summer/early fall forage quality of crested wheatgrass (Agropyron desertorum [Fisch. ex Link] J.A. Schultes), bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Love), Idaho fescue (Festuca idahoensis Elmer), bottlebrush squirreltail (Elymus elymoides [Raf.] Swezey), Thurber's needlegrass (Achnatherum thurberianum [Piper] Barkworth), and basin wildrye (Leymus cinereus [Scribn. & Merr.] A. Love) from ungrazed paddocks and paddocks grazed at vegetative, boot, and anthesis; and (2) test hypotheses that postgrazing regrowth yields were correlated with soil moisture content when grazing occurred. Crop-year precipitation for 1997 and 1998 was 134 and 205 percent of average. Crude protein (CP) and in vitro dry matter digestibility (IVDMD) of ungrazed grasses displayed expected declines in quality. Among grasses, respective 1997 CP and IVDMD means were 9.0 and 55 percent for regrowth following anthesis grazing. No regrowth followed anthesis grazing in 1998, but CP and IVDMD means from boot stage treatments were 5.5 and 47 percent, respectively. Forage conditioning responses were lower for bluebunch wheatgrass and crested wheatgrass than other grasses. Soil moisture content was a poor predictor of regrowth yields. Managed cattle grazing can successfully enhance late season forage quality.

Citation

Ganskopp, Dave; Aguilera, Lisa; Vavra, Marty. 2007. Livestock forage conditioning among six northern Great Basin grassess. Rangeland Ecology & Management. 60(1):71-78.