Persistence of Perennial Cool‐Season Grass and Legume Cultivars under Continuous Grazing by Beef Cattle

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Abstract
Persistence of highly productive forage species in pastures is essential to maximize economic returns from grazing livestock. However, most forage cultivars are neither developed nor evaluated under grazing. The objective of this study was to evaluate several cool‐season forage species and cultivars to determine their tolerance to continuous grazing. Three grazing experiments were established in 1996 in central Iowa: (i) 20 cultivars and populations of alfalfa (Medicago sativa L.), (ii) 15 cultivars representing five cool‐season legume species, and (iii) 25 cultivars and germplasms of six cool‐season grass species. Beef cattle (Bos taurus) continuously grazed the experiments for about four months in 1997 and 1998. Alfalfa yield was measured in adjacent plots. Stand survival ratings were taken each year. Among the alfalfa entries, grazing‐tolerant ‘Alfagraze’ showed high persistence but moderate yield. Several new alfalfa populations combined excellent grazing tolerance with yield equal to the best hay‐type cultivar. Kura clover (Trifolium ambiguum Bieb.) and white clover (T. repens L.) persisted better than alfalfa, birdsfoot trefoil (Lotus corniculatus L.), and red clover (T. pratense L.), with no loss of stand after two grazing years. Orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.) persisted well, though considerable variation was present among orchardgrass cultivars after the second grazing year. Reed canarygrass (Phalaris arundinacea L.) and smooth bromegrass (Bromus inermis Leyss.) stands were reduced to <10% after one grazing year. Although the severe, continuous grazing used in these experiments is not recommended, it clearly and quickly differentiates among species and cultivars for grazing tolerance.