• Botanical Composition and Diet Quality of Cattle Under a Short Duration Grazing System

      Kirby, D. R.; Parman, M. (Society for Range Management, 1986-11-01)
      A study was conducted in 1981 and 1982 at the Dickinson Experiment Station Ranch Headquarters in the mixed grass prairie of western North Dakota to determine seasonal and daily cattle diets under a short duration grazing system. Significant seasonal decreases in crude protein (CP) and in vitro digestible organic matter (IVDOM) were determined both years of the study. Dietary CP did not meet lactating and/or dry, pregnant cow requirements throughout the grazing season either year. In 1981, no seasonal difference in dietary CP and IVDOM was determined between the initiation and termination of grazing on individual paddocks. Only one significant difference occurred in 1982 when dietary CP decreased significantly between the first and last day of grazing individual paddocks in fall. Grass dominated cattle diets both years of the study. The major grasses selected were western wheatgrass (Agropyron smithii), needle-and-thread (Stipa comata), and blue grama (Bouteloua gracilis). Cattle showed no consistent seasonal trend in grass or browse selection, while forbs decreased in diets as the grazing season advanced. Selection of forage species and plant classes by cattle while they occupied a paddock varied little during seasonal collection periods throughout the study.
    • Disappearance of Forage Under Short Duration and Seasonlong Grazing

      Kirby, D. R.; Pessin, M. F.; Clambey, G. K. (Society for Range Management, 1986-11-01)
      A study was conducted in 1982 and 1983 at the Dickinson Experiment Station, North Dakota, in the mixed grass prairie to determine the effects of short duration grazing (SDG) and repeated seasonlong grazing (RSLG) by cattle on graminoid, forb, and half-shrub disappearance. Five range sites were delineated within each grazing treatment and evaluated for forage availability and disappearance. Graminoid disappearance was similar, regardless of grazing treatment, each year of the study. However, forb disappearance (i.e., utilization) increased three-fold in 1982 and more than two-fold in 1983 on the SDG treatment as compared to the RSLG treatment. Half-shrub availability and disappearance were negligible both years of the study. Spatial distribution of grazing among range sites on treatments must be evaluated with caution due to limitations in study design. Treatments were not equal-sized or replicated, and area, productivity potential, and distribution of range sites within treatments varied. Despite these limitations, no consistent pattern of site preference was discernible on either grazing treatment. In addition, a greater stocking rate (75%) and density (1400%) on the SDG treatment did not improve grazing distribution as measured by forage disappearance among the diverse range sites present.