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

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 blue-grass (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. Research QuestionPerennial forage grasses provide the basis for management intensive grazing (MIG) systems, which are rapidly increasing in popularity among dairy farmers in the northern USA and eastern Canada. This study evaluated 91 varieties of 15 grass species for persistence and productivity under a MIG system on three single-family dairy farms in southern Wisconsin. Literature SummaryHistorically, cool-season grasses have been developed and evaluated under a hay-type management, in which plots are cut by some mechanical means. This work is generally done on agricultural research stations by USDA, state, or private personnel. The grassroots movement toward increased use of MIG in dairy farming imposes different stresses on a grass plant compared with those present in a researcher's hay plots. These include more frequent defoliation, preferential removal of leaf blades, trampling, and localization of manure and urine. These stresses cannot be simulated or duplicated by mechanical means. Previous studies have shown that changes in management can greatly alter the performance ranking of grass varieties and species. Therefore, recommendations of superior forage grass varieties or species for use in MIG must be based on data collected in the appropriate management environment. Study DescriptionLocation: Three dairy farms in southern Wisconsin Soil: Fayette silt loam (two sites), Dubuque loam Grass species: Orchardgrass, tall fescue, meadow fescue, perennial ryegrass, intermediate ryegrass, Italian ryegrass, festulolium, prairie brome, smooth bromegrass, sitka bromegrass, timothy, reed canarygrass, Kentucky bluegrass, creeping foxtail, and hybrid wheatgrass. Pasture management: Rotational grazing, five or six rotations between early May and early or mid-October 1991 and 1992 Measurements: Available forage, apparent intake, and refusal were estimated for each grass variety during each grazing rotation; ground cover was measured at the completion of the experiment Applied QuestionWhich perennial grass species and varieties show superior available forage, apparent intake, and persistence under a MIG system? Within the moderately winterhardy-vigorous regrowth group, orchardgrass, tall fescue, perennial ryegrass, and meadow fescue had excellent persistence, as measured by ground cover. ‘Matua’ prairie brome did not survive the first winter. Orchardgrass and tall fescue had the highest available forage, while orchardgrass and intermediate ryegrass had the highest apparent intake on pasture. Within the very winterhardy-moderate regrowth group, timothy, Kentucky bluegrass, and creeping foxtail had the highest persistence. Reed canarygass and sitka bromegrass had the highest available forage and apparent intake. Garrison creeping foxtail had very high apparent intake, despite an average amount of available forage. Both fescue species had low apparent intake; for any given level of available forage, orchardgrass varieties always ranked higher than tall fescue varieties and ryegrass varieties always ranked higher than meadow fescue varieties in apparent intake. Thus, both meadow and tall fescue have the potential to reduce apparent intake of mixed cool-season grass pastures if they are present in large quantities. Group/speciesGround coverAvailable forageApparent intake%tons/acreModerately winterhardy-vigorous regrowthOrchardgrass791.560.69Tall fescue871.590.58Meadow fescue841.420.54Perennial ryegrass761.320.54Intermediate ryegrass461.400.63Italian ryegrass381.280.58Festulolium651.370.56Very winterhardy-moderate regrowthSitka bromegrass581.450.68Smooth bromegrass641.370.68Timothy721.360.64Reed canarygrass691.580.79Kentucky bluegrass871.330.57Creeping foxtail821.380.70Hybrid wheatgrass581.370.63Of the three reed canarygrass varieties, only two have low levels of the alkaloid gramine. The third, Vantage, has moderate to high levels, but did not differ from the other two varieties in available forage or apparent intake. Therefore, all three may be suitable for use in mixed grass pastures. ‘Clair’ timothy stood out as having the highest apparent intake and nearly the highest ground cover. These results, combined with results from previous studies, suggest that Clair is still a superior and versatile variety. ‘Bison’ intermediate ryegrass stood out as having the highest available forage and apparent intake among all the ryegrasses, even though its ground cover was relatively low. In conclusion, the study provided the beginning of a database from which to recommend perennial grass varieties for use in permanent pasture for MIG systems. It also provided the authors with valuable experience, working with the farmer-cooperators and their land, that could not have been gained on an agricultural research station. The results of this study have been distributed to over 100 000 persons, have been presented at numerous gtaziers' meetings, and have immensely improved the credibility of the Wisconsin grass evaluation program in the minds of our farmer clientele group.