An On-Farm Test of Perennial Forage Grass Varieties under Management Intensive Grazing

Abstract

Perennial cool-season grasses have historically been bred and evaluated strictly under hay managements with mechanical harvesting. Forage yield and persistence data collected under such circumstances may have little value in choosing cultivars for management intensive grazing (MIG) systems. The objectives of this study were to begin developing a database of cool-season grass cultivars for MIG and a protocol for expansion of the database: Ninety-one grass varieties were planted in randomized complete block designs in 1990 on three dairy farms in southern Wisconsin (Fayette silt loam and Dubuque loam-both fine-silty, mixed, mesic Typic Hapludalfs). Each study was rotationally grazed five or six times in 1991 and 1992. Compressed pasture heights (bulk density) were measured on each plot immediately before and after each grazing event and converted to estimates of available forage using a linear regression calibration. Apparent intake of each plot was computed as the difference between pre- and post-grazing estimates of available forage. Across all varieties, available forage ranged from 1.2 to 1.7 tons/acre, apparent intake ranged from 0.45 to 0.82 tons/acre, and ground cover (fall 1992) ranged from 18 to 93%, with significant differences observed among species and within several species. Reed canarygrass (Phalaris arundinacea L.) had markedly greater available forage and apparent intake than the other very hardy species. Creeping foxtail (Alopecuris arundinaceus Poir.) had very high apparent intake (0.70 tons/acre) and Kentucky bluegrass (Poa pratensis L.) had very low apparent intake (0.57 tons/acre) although their available forage differed by only 0.05 tons/acre. Timothy (Phleum pratense L.) varieties were highly variable, while smooth bromegrass (Bromus inermis Leyss.) varieties did not show marked differences. Many orchardgrass (Dactylis glomerata L.) varieties had extremely high available forage and apparent intake, always higher in apparent intake than tall fescue (Festuca arundinacea Schreb.) for the same level of available forage. Similarly, perennial ryegrass (Lolium perenne L.) had higher apparent intake than meadow fescue (F. pratensis Huds.) for the same level of available forage. Intermediate and Italian ryegrasses (L multiflorum Lam.), festulolium (Festulolium braunii K.A.), and 'Matua' prairie brome [Bromus unioloides (Willd.) H.B.K.] were not well adapted to the combination of MIG and harsh, relatively snow-free winters. The study provided the beginning of a database that will be extremely useful in developing credible recommendations of perennial grasses for cool-season pastures.